[Fibrocartilaginous lipoma: a clinicopathological analysis of six cases].

Objective: To investigate the clinicopathological characteristics, immunophenotype, molecular genetics and differential diagnoses of fibrocartilaginous lipomas which consist of adipose tissue, fibrocartilage and fibrous elements. Methods: The clinicopathological features, immunohistochemical profiles and molecular profiles in six cases of fibrocartilaginous lipomas diagnosed at Foshan Traditional Chinese Medicine Hospital, Fudan University Shanghai Cancer Center, the Fifth Affiliated Hospital of Zhengzhou University and the Fourth Affiliated Hospital of Harbin Medical University from January 2017 to February 2022 were included. The follow-up information, diagnosis and differential diagnoses were evaluated. Results: There were three males and three females with a median age of 53 years (range 36-69 years) at presentation. Tumors were located in the extremities, the head and neck region and trunk; and presented as painless masses that were located in the subcutaneous tissue or deep soft tissue. Grossly, three cases were well defined with thin capsule, one case was well circumscribed without capsule, two cases were surrounded by some skeletal muscle. The tumors were composed of fatty tissue with intermingled gray-white area. The tumors ranged from 1.50-5.50 cm (mean 2.92 cm). Microscopically, the hallmark of these lesions was the complex admixture of mature adipocytes, fibrocartilage and fibrous element in varying proportions; the fibrocartilage arranged in a nodular, sheet pattern with some adipocytes inside. Tumor cells had a bland appearance without mitotic activity. Immunohistochemical analysis using antibodies to SMA, desmin, S-100, SOX9, HMGA2, RB1, CD34, adipopholin was performed in six cases; the fibrocartilage was positive for S-100 and SOX9, adipocytes were positive for S-100, adipopholin and HMGA2; CD34 was expressed in the fibroblastic cells, while desmin and SMA were negative. Loss of nuclear RB1 expression was not observed. Other genetic abnormalities had not been found yet in four cases. Follow-up information was available in six cases; there was no recurrence in five, and one patient only underwent biopsy of the mass. Conclusions: Fibrocartilaginous lipoma is a benign lipomatous tumor with mature adipocytes, fibrocartilage and fibrous elements. By immunohistochemistry, they show the expression of fat and cartilage markers. No specific molecular genetics changes have been identified so far. Familiarity with its clinicopathological features helps the distinction from its morphologic mimics.

Primary Cutaneous Alveolar Rhabdomyosarcoma in an Elderly Adult: A Rare Potential Mimic of Merkel Cell Carcinoma.

ABSTRACT: Rhabdomyosarcoma (RMS) rarely arises as a primary skin tumor. It is also very rare in older adults, especially the alveolar type. We report an 80-year-old White woman who presented with a painful, erythematous, raised lesion (2 × 3.5 cm) above the left knee that was fixed within the skin, yet mobile about underlying soft tissue. A punch biopsy showed monotonous malignant round blue cells involving the dermis. Immunostains showed diffuse expression of CD56, focal chromogranin, focal dot-like pancytokeratin, CK7, and neurofilament, but negative for synaptophysin, CK20, SOX-10, MUM-1, CD43, TTF-1, and CD99. A CK20-negative variant of Merkel cell carcinoma was initially favored, but given the unusual immunophenotype and the presence of cellular dyscohesion, desmin and myogenin stains were performed, both of which were diffusely positive. Molecular testing revealed rearrangement of PAX3 and FOXO1 loci, confirming the diagnosis of alveolar RMS. PET/CT showed a probable 1.9-cm left inguinal lymph node metastasis; no internal or deep soft tissue primary tumor mass was identified, supporting a true primary cutaneous origin. Alveolar RMS may express keratins and neuroendocrine markers, making it easy to confuse with Merkel cell carcinoma on those exceptionally rare instances, when it arises in the skin of older adults.

Lipoblastomas presenting in older children and adults: analysis of 22 cases with identification of novel PLAG1 fusion partners.

Lipoblastomas are benign neoplasms of embryonal white fat that typically present in the first 3 years of life and show a lobular arrangement of maturing adipocytes with variable degrees of myxoid change. We systematically studied the clinicopathologic and genetic features of lipoblastomas arising in older children and adults. Cases with a diagnosis of lipoblastoma or maturing lipoblastoma in patients >3 years of age were retrieved from our archives. Immunostaining for CD34 and desmin and molecular studies (FISH, RNA sequencing) were performed. Twenty-two cases (8F; 14M) were identified in patients ranging from 4 to 44 years of age (median 10 years). Sites included extremity (n = 15), head and neck (n = 4), and trunk (n = 3) with tumor sizes varying from 1.6 to 17.5 cm (median 5). Only three tumors had histologic features of "conventional" lipoblastoma. The majority of tumors (n = 14) were composed of variably sized lobules of mature adipose tissue partitioned by thin fibrous septa ("maturing"). The remaining five cases consisted predominantly of bland spindled to plump ovoid cells embedded in a fibrous stroma, with a vaguely plexiform arrangement of small myxoid and adipocytic nodules ("fibroblastic"). CD34 was diffusely positive in all cases tested (21/21), while desmin immunoreactivity was identified in 12 of 21 cases (diffuse = 7, focal = 5). PLAG1 rearrangements were identified in 13 tumors in the entire cohort (59%), including all 5 fibroblastic tumors. RNA sequencing detected eight PLAG1 fusion partners, of which two were known (CHCHD7 and COL3A1) and six were novel (SRSF3, HNRNPC, PCMTD1, YWHAZ, CTDSP2, and PPP2R2A). Twelve cases had follow-up (1-107 months; median 21 months), and no recurrences were reported. Lipoblastomas may occur in older children and adults and may be difficult to recognize due to their predominantly adipocytic or fibrous appearance. Awareness that lipoblastomas may occur in older patients, careful evaluation for foci showing more typical morphologic features, ancillary immunohistochemistry for CD34 and desmin, and molecular genetic studies to identify PLAG1 rearrangements are the keys to recognizing these tumors.

Myofibroblastoma of the breast showing rare palisaded morphology and uncommon desmin- and CD34-negative immunophenotype: A case report.

Myofibroblastoma is a rare benign mesenchymal tumor typically arising in the breast. We report a diagnostically challenging case of myofibroblastoma of the breast showing a rare palisaded morphology and an uncommon desmin- and CD34-negative immunophenotype. A 73-year-old man underwent an excision for an 8 mm-sized breast mass. Histology revealed that the tumor was composed of fascicles of bland spindle cells showing prominent nuclear palisading and Verocay-like bodies. First, schwannoma, malignant peripheral nerve sheath tumor, and synovial sarcoma were suspected given the palisaded morphology. However, none of them was confirmed by immunohistochemical or molecular analyses. Next, a palisaded variant of myofibroblastoma was suspected by the morphology and coexpression of estrogen, progesterone and androgen receptors, BCL2 and CD10 in immunohistochemistry. However, the key diagnostic markers, desmin and CD34, were both negative. Finally, the diagnosis of myofibroblastoma was confirmed by detecting RB1 loss in immunohistochemistry and monoallelic 13q14 deletion (RB1 and FOXO1 loss) by fluorescence in situ hybridization assay. For the correct diagnosis of myofibroblastoma, it is important for pathologists to recognize the wide morphological spectrum, including a palisaded morphology, and the immunophenotypical variations, including desmin- and CD34-negative immunophenotypes, and to employ a comprehensive diagnostic analysis through combined histological, immunohistochemical and molecular evaluations.

Insight into the Characteristics of Novel Desmin-Immunopositive Perivascular Cells of the Anterior Pituitary Gland Using Transmission and Focused Ion Beam Scanning Electron Microscopy.

Recently, another new cell type was found in the perivascular space called a novel desmin-immunopositive perivascular (DIP) cell. However, the differences between this novel cell type and other nonhormone-producing cells have not been clarified. Therefore, we introduced several microscopic techniques to gain insight into the morphological characteristics of this novel DIP cell. We succeeded in identifying novel DIP cells under light microscopy using desmin immunocryosection, combining resin embedding blocks and immunoelectron microscopy. In conventional transmission electron microscopy, folliculostellate cells, capsular fibroblasts, macrophages, and pericytes presented a flat cisternae of rough endoplasmic reticulum, whereas those of novel DIP cells had a dilated pattern. The number of novel DIP cells was greatest in the intact rats, though nearly disappeared under prolactinoma conditions. Additionally, focused ion beam scanning electron microscopy showed that these novel DIP cells had multidirectional processes and some processes reached the capillary, but these processes did not tightly wrap the vessel, as is the case with pericytes. Interestingly, we found that the rough endoplasmic reticulum was globular and dispersed throughout the cytoplasmic processes after three-dimensional reconstruction. This study clearly confirms that novel DIP cells are a new cell type in the rat anterior pituitary gland, with unique characteristics.

Three-dimensional visualization of cleared human pancreas cancer reveals that sustained epithelial-to-mesenchymal transition is not required for venous invasion.

Venous invasion is three times more common in pancreatic cancer than it is in other major cancers of the gastrointestinal tract, and venous invasion may explain why pancreatic cancer is so deadly. To characterize the patterns of venous invasion in pancreatic cancer, 52 thick slabs (up to 5 mm) of tissue were harvested from 52 surgically resected human ductal adenocarcinomas, cleared with a modified iDISCO method, and labeled with fluorescent-conjugated antibodies to cytokeratin 19, desmin, CD31, p53 and/or e-cadherin. Labeled three-dimensional (3D) pancreas cancer tissues were visualized with confocal laser scanning or light sheet microscopy. Multiple foci of venous and even arterial invasion were visualized. Venous invasion was detected more often in 3D (88%, 30/34 cases) than in conventional 2D slide evaluation (75%, 25/34 cases, P < 0.001). 3D visualization revealed pancreatic cancer cells crossing the walls of veins at multiple points, often at points where preexisting capillary structures bridge the blood vessels. The neoplastic cells often retained a ductal morphology (cohesive cells forming tubes) as they progressed from a stromal to intravenous location. Although immunolabeling with antibodies to e-cadherin revealed focal loss of expression at the leading edges of the cancers, the neoplastic cells within veins expressed e-cadherin and formed well-oriented glands. We conclude that venous invasion is almost universal in pancreatic cancer, suggesting that even surgically resectable PDAC has access to the venous spaces and thus the ability to disseminate widely. Furthermore, we observe that sustained epithelial-mesenchymal transition is not required for venous invasion in pancreatic cancer.

Therapeutic Effects of Resveratrol Liposome on Muscle Injury in Rats.

BACKGROUND In this study we prepared liposome microbubbles loading resveratrol (LMLR) and evaluated its therapeutic effect on injury of gastrocnemius muscle in rats. MATERIAL AND METHODS LMLR was prepared and characterized by particle size, potential, and microscopy, and a rat model of acute blunt injury of gastrocnemius muscle was established. After treatments with resveratrol or LMLR, the therapeutic effects were evaluated by hematoxylin-eosin (HE) staining. The expression of MHCIIB and vimentin in mRNA level was measured by real-time PCR. The expression of desmin and collagen I protein was assessed by immunohistochemistry. RESULTS LMLR showed regular cycle shape in a size of ~1000 nm. LMLR was negatively charged (-30 mV). The in vitro release of LMLR was close to 80% at 10 h and 90% at 48 h. Acute gastrocnemius muscle injury was established in rats and tissue recovery was observed after LMLR treatment as evidenced by HE staining, decreased expression of MHCIIB, and increased expression of vimentin. Moreover, LMLR treatment obviously facilitated desmin expression and reduced collagen I expression. CONCLUSIONS LMLR is effective in treating acute blunt injury of gastrocnemius muscle in rats.

Bladder Fetal Rhabdomyoma Intermediate Type.

INTRODUCTION: Rhabdomyomas are benign tumors of striated muscle, the bladder localization is very rare. CLINICAL CASE: We present an 87-year-old male consulting for gross hematuria. Cystoscopy was done with evidence of bulged bladder mucosa in right side wall and dome. Post-transurethral resection of the bladder (TURB) pathological anatomy was negative for malignancy. As extension study abdominopelvic computed tomography was performed identifying a bladder thickening of right posterior sidewall and an increased density of the adjacent fat. Second TURB was performed and a fetal bladder rhabdomyoma intermediate type was obtained. We performed another biopsy to confirm this rare pathology, with the same diagnosis. Subsequently, the patient continues with hematuria deciding on hemostatic radiotherapy (not candidate for cystectomy or arterial embolization). Currently, the patient is asymptomatic. DISCUSSION: Bladder rhabdomyomas are rare tumors, and, in fact, there have been only 5 papers published. Some cases are only isolation cited in the bladder mesenchymal tumors, and other polemic cases in which clinical and macroscopic characteristics remembered a rhabdomyosarcoma. The importance of this publication case is the macro- and microscopic images that can corroborate the final diagnosis, helping us to differentiate between rhabdomyoma, rhabdomyofibroma, or the malignant rhabdomyosarcoma, and shows the treatment possibilities of these tumors.

[Clinicopathological analysis of aggressive angiomyxoma of soft tissue in abdomino-pelvic cavity].

Aggressive angiomyxoma is a rare mesenchymal tumor. To discuss the clinicopathological characteristics, treatment and prognosis of aggressive angiomyxoma, four cases of aggressive angiomyxoma of soft tissue in abdominopelvic cavity were collected from January 2015 to August 2017 in Peking University International Hospital. The clinical data, imaging examination, histopathological features, immunophenotype, therapy and prognosis were analysed. The related literatures were reviewed. All of the patients were adult females, age range from 27 to 49 years and mean 33 years. The clinical complaint was abdominal distention with no definite predisposing factor, or occasional physical-exam finding with no obvious discomfort. Three cases were primary and one case was recurrent. Typical layered or swirled structural sign was presented by CT and MRI scanning of three cases. All tumors located in the pelvic cavity, and attached to the uterus, vagina, rectum, bladder or ureter. One case was involved in the abdominal cavity simultaneously,adhesive to the spine, inferior vena cava and spleen. The gross appearance of tumors was from 5 to 22 cm in maximum diameter. The sectioned surfaces were soft, solid, white or yellow-gray, focally accompanied by edema, mucoid degeneration or cystic change. Microscopic observation showed that tumor cells were short spindle shaped and little atypical, the stroma was loose like edematous mucus or collagen, and the vessels were rich in thin and thick-wall. Partially the vessel wall expressed hyaline degeneration. Also tumors might infiltrate surrounding tissue, such as fat or nerve. The immunohistochemistry results of all cases were estrogen receptor and progesterone receptor diffusely moderate positive, Desmin and smooth muscle actin mostly positive, whereas CD34 expressed only in vessel and S-100 protein, CD117 and Dog1 all negative. All the tumors were complete surgical excision. During follow-up, one case recurred the second time. Our conclusions are the diagnosis of aggressive angiomyxoma is based on pathological morphology supplemented by immunohistochemistry, and the tumor may relapse after surgical resection.

[Myxoid variant of angiomatoid fibrous histiocytoma: a clinicopathologic analysis of 3 cases].

Objective: To study clinicopathologic features, diagnosis and differential diagnosis of myxoid variant of angiomatoid fibrous histiocytoma (AFH). Methods: Three cases of myxoid variant of AFHs were collected from First Affiliated Hospital of Nanjing Medical University during 2008 and 2017. EnVision method and fluorescence in situ hybridization(FISH) were used to detect immunophenotype and EWSR1 gene rearrangement, respectively. Results: There were 2 males and l female with age at 13, 31, and 42 years, respectively. The patients presented with a painless mass located superficially (subcutaneous or submucosal) in two cases or deep-seated (retroperitoneum) in one case. Grossly, the diameters of tumors were 1, 7, and 2 cm, respectively. The cut surface was solid and firm, tan to gray in colour. Histologically, the circumscribed tumor had fibrous pseudocapsule and peritumoal lymphoplasmacytic infiltrates. The tumor cells arranged in vaguely nodular growth pattern, with prominent myxoid stroma (present in 60% to 100% of the entire tumor). In hypocellular myxoid areas, the spindle to stellate tumor cells arranged in cords or reticular pattern, or in a haphazard manner. However, histiocytoid cells arranged in fascicular, sheet-like, or whorled growth pattern, as in classical AFH, were also identified in hypercelluar areas. Mild to moderate atypia was observed with low mitotic rate of (0-2)/10 HPF. Tumor necrosis was not seen. One case presented with slit-like hemorrhage and sclerosing collagen intermingled with myxoid matrix was identified in 1 case. Immunohistochemically, all cases were positive for CD68 and CD163. Two of three were positive for desmin, EMA, CD99 and one for Calponin, SMA. All cases were negative for S-100 protein, CD34, CD31, CD35, CD21 and CKpan. FISH detection was positive for EWSRl gene in all cases. Available clinical follow-up was obtained in 2 cases, revealing no evidence of disease in 6 and 89 months, respectively. Conclusions: Myxoid variant of AFH is a histological subtype of AFH, with clinical features, immunophenotypes, genomic profiles and biological behavior similar to typical AFH. Their unusual morphology is easily confused with a variety of other myxoid mesenchymal neoplasms, including myoepithelioma and nerve sheath tumors.

[Pleomorphic and dedifferentiated leiomyosarcoma: a clinicopathologic analysis].

Objective: To investigate the clinicopathologic features, differential diagnosis and biological behavior of pleomorphic leiomyosarcoma (PLMS) and dedifferentiated leiomyosarcoma (DLMS). Methods: Forty-nine cases were collected from November 2007 to December 2016, including eight that diagnosed at Fudan University Shanghai Cancer Center, and 41 consultation cases. The clinical findings and pathologic features were reviewed. Immunophenotype was obtained in 33 cases and follow-up information was available in 38 cases. Results: There were 22 males and 27 females with ages ranging from 24 to 83 years (mean 52.5 years). Fifteen cases occurred in extremities, 14 in deep body cavity, 11 in the trunk, 4 in the head and neck, 2 in the bladder, and 1 each in the inguinal region, perineum and femoral vein, respectively. Tumor sizes ranged from 3 to 30 cm (mean 9.1 cm). The tumors were composed of at least small foci of typical leiomyosarcoma (LMS) and areas of high-grade pleomorphic/undifferentiated sarcoma. The typical LMS component showed the characteristic morphology of smooth muscle differentiation and was low to intermediate grade in most cases. Pleomorphic areas were mainly composed of atypical spindle and polygonal cells admixed with variable large, bizarre atypical cells and multinuclear giant cells, mostly mimicking undifferentiated pleomorphic sarcoma. The pleomorphic and leiomyosarcomatous areas were usually intermixed, but the demarcation may be distinct or gradual in some cases. The classical LMS component was positive for at least one myogenic marker: α-SMA in 97.0%(32/33), desmin in 72.7%(24/33), H-caldesmon in 90.9% (20/22), MSA in 14/16, and calponin in 15/15 of cases. The pleomorphic sarcoma component was reactive for at least one myogenic marker in 87.9% (29/33) of cases, usually showing focal and less intense immunoreactivity than classical LMS component: α-SMA was positive in 81.8%(27/33), desmin in 48.5%(16/33), H-caldesmon in 72.7% (16/22), MSA in 12/16, and calponin in 11/15 of cases. Based on staining for muscle markers in the pleomorphic component, 29 cases were designated as PLMS, 4 as DLMS. Ki-67 index ranged from 15% to 70% (mean 40%). Follow-up data was available in 38 cases (77.6%), of which 11 patients (28.9%) died of disease, 12 patients were alive with unresectable or recurrent disease, 14 patients were alive with no evidence of disease and another one died of unrelated cause. The median disease-free and overall survival was 6 and 10 months respectively. Twelve patients exhibited local recurrence and 11 developed metastases. The median interval to progression was 8 months. Conclusions: The identification of areas of typical LMS is crucial for accurate diagnosis of PLMS and DLMS. Both PLMS and DLMS show more aggressive behavior and poorer prognosis than ordinary LMS.

[Angiofibroma of soft tissue: a clinicopathologic analysis of 24 cases].

Objective: To investigate the clinicopathologic and genetic features, pathologic diagnosis and differential diagnosis of angiofibroma of soft tissue(AFST). Methods: The clinicopathologic characteristics of 24 cases diagnosed at Fudan University Shanghai Cancer Center from 2011 to 2017 were analyzed; immunohistochemical staining and interphase fluorescence in situ hybridization (FISH) were performed, and the literatures were also reviewed. Results: There were 15 male and 9 female (male∶female=1.7∶1.0) patients with age of onset ranging from 8 to 68 years (mean, 45 years). Fourteen cases occurred in extremities, including upper limbs (n=3) and lower limbs (n=11); seven cases were in the trunk, and 1 case each was in the temporal region, retroperitoneum and liver, respectively. Clinically, the tumors usually presented as a slowly growing painless mass. Tumor sizes ranged from 0.8 to 14 cm (mean 4.6 cm). Microscopically, most lesions were well-circumscribed, with fibrous capsules. Few cases infiltrated the surrounding fibrofatty tissue focally. The tumors were mainly composed of sparse short spindle cells and numerous small, branching, thin-walled blood vessels distributed in amyxoid, fibromyxoid or collagenous matrix, often accompanied by medium-sized, round or irregular and ecstatic vessels at the tumor periphery.By immunohistochemistry, all tested cases expressed vimentin (5/5), and showed variable positivity for EMA (2/4), ER (1/2), PR (2/3), α-SMA (1/18)and desmin (1/10). Ki-67 proliferation index were all less than 5%. CD34, CD31 and ERG staining clearly outlined the contours of blood vessels in the stroma. Four cases were tested for NCOA2 gene rearrangement by FISH, of which three were positive. Follow-up data was available in 17 patients (range, 3 to 69 months; mean, 30 months) were all free of disease. Conclusions: Soft tissue angiofibroma is a benign fibroblastic neoplasm characterized by a prominent and complex vasculature set in a myxoid-to-collagenous stroma, and cytogenetically a distinctive NCOA2 gene rearrangement. Caution should be exercised for the possibility of potentially misinterpretation of AFST as vascular tumors and other myxoid soft tissue tumors.

[Myofibroma/myofibromatosis: a clinicopathologic analysis of 9 cases].

Objective: To investigate the clinical and histological features, diagnosis and differential diagnosis of myofibroma/myofibromatosis. Methods: The clinical data and pathology features of nine cases of myofibroma/myofibromatosis were collected from August 2011 to November 2016 in Affiliated Drum Tower Hospital, Nanjing University Medical School and Children's Hospital of Nanjing Medical University. Immunohistochemistry(IHC), PDGFRB molecular analysis and ETV6-NTRK3 gene fusion were performed and relevant literature reviewed. Results: There were 7 males and 2 females, with age ranging from 3 days to 18 years (mean 5 years). The tumors were located in head and neck (eight cases) and trunk (one case). Clinically, the tumors presented as freely movable nodules. Microscopically, they appeared biphasic with alternating light- and dark-staining areas. The light-staining area consisted mainly of plump myoid spindle cells with eosinophilic cytoplasm arranged in nodules, short fascicles, or whorls.The dark-staining area was composed of round or polygonal cells with slightly hyperchromatic nuclei or small spindle cells arranged around a distinct hemangiopericytoma-like vascular pattern. IHC showed the tumor cells in the light-staining area were strongly positive for vimentin and SMA, while cells in dark-staining area were strongly positive for vimentin, and weakly for SMA. Tumor cells were negative for desmin, S-100 protein, h-Caldesmon, CD34 and STAT6. Analysis of PDGFRB mutations was performed in seven cases. Two cases showed 12 exon point mutation c. 1681 c>T(p.R561C), one case showed 14 exon point mutation c. 1998C>G (p.N666K). ETV6-NTRK3 gene fusion was not detected by fluorescence in situ hybridization in four patients under three years old. All cases were followed for 6 to 68 months, with two recurrences. Conclusions: Myofibroma/myofibromatosis is an uncommon benign myofibroblastic tumor of infancy and childhood. The tumor can appear biphasic, and may show PDGFRB point mutation which is of potential diagnostic value.

[Lipofibromatosis: a clinicopathological analysis of eight cases].

Objective: To investigate the clinicopathological characteristics and differential diagnosis of lipofibromatosis. Methods: The clinicopathological features and immunohistochemical profiles in 8 cases of lipofibromatosis diagnosed at Fudan University Shanghai Cancer Center from January 2008 to June 2017 were studied. Molecular analysis of ß-catenin mutation by Sanger sequencing, NTKR1 and ETV6 rearrangements by FISH were performed. The follow up information was evaluated and the literature was reviewed. Results: There were 4 males and 4 females with a median age of 1.5 years at presentation (range, 3 months-9 years). Tumor arose in the hand (4 cases), foot (2 cases) and trunk (2 cases), manifesting as a painless subcutaneous mass. Two cases were congenital, one with tumor noted at birth and the others shortly after birth. Grossly, the tumors were poorly defined and irregularly shaped, composed predominantly of fatty tissue which was mingled with fibrous element. They ranged from 1 to 5 cm in size (mean, 2.6 cm). Microscopically, they were characterized by variably sized lobules of adipose tissue traversed by fascicles, bundles or trabeculae of proliferative fibroblasts and myofibroblasts, resembling desmoid tumor. In 2 cases, the tumor infiltrated adjacent skeletal muscles. On high power, the spindled fibroblasts and myofibroblasts had a bland appearance with very low mitotic activity (<1/10 HPF). By immunohistochemistry, they showed variable staining of α-SMA, MSA, CD34 and CD99, with negativity for ß-catenin, desmin, h-CALD, EMA, ALK, and S-100 protein. Ki-67 index was low (<2%). Molecular analysis showed no mutation of ß-catenin gene (0/3), no NTRK1 gene rearrangement (0/3) and no ETV6 gene rearrangement (0/2). Follow up information was available in 6 patients, revealed local recurrence in two and persistent disease in one. Conclusions: Lipofibromatosis is a special variant of infantile fibromatosis, which has a predilection for the distal portion of the extremities of neonates and infants and characterized by lobules of adipose tissue traversed by demoid tumor-like fibroblasts and myofibroblasts. However, it differs from desmoid tumor by harboring no mutation of ß-catenin gene. Familarity with its clinicopathological characteristics helps the distinction from its morphological mimics.

[Clinicopathologic features of glomus tumor of the kidney].

Objective: To investigate the clinicopathologic and differential diagnostic features of glomus tumor of the kidney. Methods: Four cases of glomus tumor of the kidney were collected from the archives of Peking University Third Hospital, the Second Hospital of Tianjin Medical University, Ningbo Yinzhou Second Hospital and Zhejiang Provincial People's Hospital between January 2012 to June 2017; the clinical and radiologic features, histomorphology, immunohistochemistry, ultrastucture and prognosis were analyzed and the relevant literature was reviewed. Results: Patients consisted of 2 men and 2 women with ages ranging from 37 years to 66 years (mean 55 years). Three patients had history of hypertensive disease (grade Ⅱ, 3 to 10 years). The tumors measured in maximum diameter from 3.0 cm to 4.0 cm (mean 3.6 cm) and showed gray-white to yellow and tan on cut surface. Macroscopical examinations showed all tumors were circumscribed but non-encapsulated. Histologically, 1 tumor presented as glomus tumor with extensive myxoid change, 1 as cellular and solid pattern glomus tumor, 1 as glomangioma with focal myopericytoma-like pattern and 1 as symplastic glomus tumor with areas resembling myopericytoma. The tumor cells in two cases showed scant cytoplasm and uniform, bland-appearing nuclei without mitoses. In one case, the tumor cells were epithelioid with abundant eosinophilic cytoplasm and relatively well-defined cell borders. There was an increased mitosis of 4/50 HPF; however, no evidence of atypical mitosis or nuclear atypia was noted. In the symplastic glomus tumor the tumor cells showed frequently nuclear pleomorphism without mitoses. By immunohistochemistry, all tumors showed strong and diffuse reactivities to at least 3 of the 4 muscle-associated markers (SMA, h-Caldesmon, MSA and Calponin), 3 tumors strongly and diffusely expressed collagen Ⅳ, 2 expressed CD34 and 1 focally expressed desmin; whereas markers including epithelial, neuroendocrine, nephrogenic, melanoma-associated, STAT6, S-100 protein, CD117 and ß-catenin all were negative in all the 4 tumors. Ultrastuctural analysis was done in 2 cases and showed prominent cytoplasmic actin bundles and pericellular basement membrane, and lacking of rhomboid renin crystals in both tumors. The hypertension persisted after surgical resection for all the 3 patients with this medical history. Follow-up information (range: 6-64 months, mean: 44 months)showed that no evidence of local recurrence or distant metastasis was identified in all 4 patients. Conclusions: Glomus tumor rarely occurs in the kidney and usually has a good prognosis. Careful attention to its morphology with the judicious use of immunohistochemistry and ultrastuctural analysis can be helpful for its diagnosis and differential diagnosis.

[Gastrointestinal leiomyoma with interstitial cells of Cajal: mimicker of gastrointestinal stromal tumor].

Objective: To study clinical and pathologic characteristics of leiomyomas of the gastrointestinal tract, and to investigate the distribution characteristics of interstitial cells of Cajal ( ICCs ) in gastrointestinal leiomyomas. Methods: One hundred and forty-seven cases of leiomyomas of gastrointestinal tract were collected at the Second Affiliated Hospital of Zhengzhou University from June 2012 to June 2017. Clinical and pathologic findings were analyzed, combined with immunohistochemistry, Alcian blue-osafranin staining and molecular study. Results: The age of patients ranged from 13-82 years with mean age of 52 years. Male to female ratio was about 1∶2. Histologically, all tumors were composed of ovoid to spindle cells arranged in short intersecting fascicles. All tumors were diffusely and strongly positive for smooth muscle antibodies, desmin and h-caldesmon by immunohistochemical staining. A prominent interspersed subpopulation of elongated/dendritic-like cells with CD117 and DOG1 positivity (accounting for 1% to 30% of all tumor cells) and negative for Alcian blue-osafranin staining was identified in all esophageal leiomyomas, 16 of 20 (80%) gastric leiomyomas and 3 of 12 small bowel leiomyomas, but none in colonic/rectal leiomyomas. Mutational analysis in 16 cases showed absence of mutation in exons 9, 11, 13 or 17 of C-KIT and exons 12 or 18 of PDGFRA. Conclusions: ICCs are identified in esophageal and gastric leiomyomas, as well as in small percentage of intestinal leiomyomas. Such findings may bring significant diagnostic pitfalls for misdiagnosis as gastrointestinal stromal tumor. Careful attention to the distribution of CD117 and DOG1 positive cells and molecular mutation analysis of C-KIT and PDGFRA may be necessary to establish the correct diagnosis.

New Description of Telocyte Sheaths in the Bovine Uterine Tube: An Immunohistochemical and Scanning Microscopic Study.

Telocytes are a special type of interstitial cells characterized by distinctive cellular extensions with alternating thin segments (podomers) and dilations (podoms). Telocytes establish contact with various cells and structures, but their role in the regulation of the function of many cell types is still obscure. The aim of the current study was to investigate the morphology, histochemistry, and immunohistochemistry of telocytes, and their distribution, organization, and morphometric measurements in different layers of the adult bovine uterine tube. Telocytes showed positive immunostaining for CD117, S-100 protein, vimentin, desmin, α-smooth muscle actin, tubulin, laminin, estrogen receptor-α, and progesterone receptor. They were organized in different types of sheaths: subepithelial, inner/outer perimuscular, and intramuscular sheaths. Telocytes were scattered in the lamina propria, in the muscular layer, and the serosa. According to their size, they were grouped into different types of telocytes: small, large, and giant telocytes. Small telocytes were the most common type and located in all layers; large telocytes were observed in the epithelium, lamina propria, and inner/outer perimuscular and intramuscular sheaths, and giant telocytes were found in the external layer of the outer perimuscular sheath. Telocytes were connected by thin and thick telopodes (fenestrated membranes). Fenestrated membranes enabled connections between telocytes along the entire muscular wall of the uterine tube. Telocytes established an extensive biological network of different types of cells and structures, including epithelial, muscular, and mast cells, blood vessels, glomus, and nerve fibers. We hypothesize that telocytes help to organize the functional coordination between different types of cells in the uterine tube.

Establishment and characterization of uterine sarcoma and carcinosarcoma patient-derived xenograft models.

OBJECTIVE: Uterine sarcomas (US) and carcinosarcomas (CS) are rare, aggressive cancers. The lack of reliable preclinical models hampers the search for new treatment strategies and predictive biomarkers. To this end, we established and characterized US and CS patient-derived xenograft (PDX) models. METHODS: Tumor fragments of US and CS were subcutaneously implanted into immunocompromised mice. Engrafted xenograft and original tumors were compared by means of histology, immunohistochemistry, whole-genome low-coverage sequencing for copy number variations, and RNA sequencing. RESULTS: Of 13 implanted leiomyosarcomas (LMS), 10 engrafted (engraftment rate of 77%). Also 2 out of 7 CS (29%) and one high-grade US (not otherwise specified) models were successfully established. LMS xenografts showed high histological similarity to their corresponding human tumors. Expression of desmin and/or H-caldesmon was detected in 8/10 LMS PDX models. We noticed that in CS models, characterized by the concomitant presence of a mesenchymal and an epithelial component, the relative distribution of the components is varying over the generations, as confirmed by changes in vimentin and cytokeratin expression. The similarity in copy number profiles between original and xenograft tumors ranged from 57.7% to 98.2% for LMS models and from 47.4 to 65.8% for CS models. Expression pattern stability was assessed by clustering RNA expression levels of original and xenograft tumors. Six xenografts clustered together with their original tumor, while 3 (all LMS) clustered apart. CONCLUSIONS: We present here a panel of clinically annotated uterine sarcoma and carcinosarcoma PDX models, which will be a useful tool for preclinical testing of new therapies.

Osteogenic Melanoma With Desmin Expression.

BACKGROUND: Osteogenic differentiation is rarely seen in melanomas, when it occurs it is mainly in acral lesions. METHODS: We report a case of an osteogenic melanoma in a 49-year-old woman who presented with a pigmented lesion in the subungueal region of her left hallux. The lesion was ulcerated and infiltrated until the deep dermis without bone involvement. RESULTS: The tumor was composed of pleomorphic atypical epithelioid and fusiform cells disposed in nests or cords, with vesicular nuclei and prominent central nucleoli. Focal lentiginous proliferation of large atypical melanocytes was present along the dermoepidermal junction. Areas of osteoid matrix focally mineralized were disposed in trabeculae, and there were islands of neoplastic cells. Immunohistochemistry revealed strong expression of S-100 protein and, unexpectedly, of desmin. Focal expression of Melan-A, microphthalmia transcription factor, and HMB-45 is also revealed. Mutations in BRAF and NRAS genes were not present. The patient was submitted to an amputation of the left hallux with negative sentinel lymph node. CONCLUSION: The importance of recognizing osteogenic melanoma is based on difficulties for histologic recognition and its differentials diagnosis.