An Atypical Fibroxanthoma and Intradermal Nevus Collision Tumor-Potential for Misdiagnosis.

Atypical fibroxanthomas (AFX) are rare cutaneous tumors, which typically present as a solitary ulcerated papule or nodule on sun-damaged skin. Despite malignant-appearing features on histology, AFX typically pursue a benign clinical course. In rare instances, AFX can form collision tumors with other lesions. However, to the best of our knowledge, AFX in collision with a nevus has never been previously reported. In this study, we describe such a lesion for its novelty and challenge in diagnosis, as this case was originally considered to be melanoma arising in a nevus. On histologic examination, there were 2 distinct populations of cells; one composed of markedly atypical and pleomorphic epithelioid and oval to spindled cells, consistent with AFX, and the other, a bland-appearing intradermal nevus with congenital features. The AFX population stained positive with smooth muscle actin, CD10, and CD68 and was negative for S100, SOX10, Melan-A, desmin, pancytokeratin, CK5/6, and p63. Deep to this was a second population of small, bland-appearing melanocytes in a broad, band-like distribution. This unusual collision tumor between AFX and an intradermal nevus highlights the important role immunohistochemistry plays in avoiding the misdiagnosis and potential overtreatment of benign or low-grade lesions, and in identifying potential mimickers.

Novel EWSR1-SMAD3 Gene Fusions in a Group of Acral Fibroblastic Spindle Cell Neoplasms.

Benign/low-grade fibroblastic tumors encompass a broad spectrum of tumors with different morphologies and molecular genetic abnormalities. However, despite significant progress in recent genomic characterization, there are still tumors in this histologic spectrum that are difficult to classify, lacking known molecular characteristics. Triggered by a challenging congenital spindle cell neoplasm arising in the heel of a 1-year-old boy, we applied RNA sequencing for genetic discovery and identified a novel EWSR1-SMAD3 gene fusion. On the basis of the index case superficial acral location and fibroblastic appearance with a nonspecific immunophenotype, we searched our files for similar cases and screened them by fluorescence in situ hybridization for these abnormalities. Thus an identical EWSR1-SMAD3 fusion was identified in 2 additional spindle cell tumors with similar clinicopathologic features. Both cases occurred in the feet of adult women (58 and 61 y old) and were characterized by distinctive nodular growth with zonation pattern of peripheral hypercellular areas arranged in short fascicles, transitioning to hypocellular central areas of hyalinization and infarction. Focal stippled calcification in the collagenous area was present in 1 case. All 3 tumors had similar immunoprofiles, being negative for SMA, CD34, CD31, and S100, but showing consistent ERG positivity of uncertain significance. Follow-up information was available in 2 patients who developed local recurrences after incomplete initial excisions, at 5 and 14 months, respectively. None developed metastatic disease. In summary, we report a group of locally recurrent superficial acral tumors, characterized by bland spindle cell fascicular growth, occasional zonation pattern, ERG positivity, and recurrent EWSR1-SMAD3 gene fusions.

[Desmoplastic fibroblastoma: a clinicopathologic analysis of 7 cases].

Objective: To investigate the clinical features, immunohistochemical and differential diagnosis of desmoplastic fibroblastoma. Methods: The clinical data and pathology features of 7 cases of desmoplastic fibroblastoma were collected and immunohistochemical study were carried out in all cases with a review of the literatures. Results: There were 2 males and 5 females, with age ranging from 31 to 71 years (average and mean age were 59 and 61 years, respectively). The tumors were located in extremities and abdomen (left toe and right toe, right foot back, left leg and right thigh, right forearm and left hepatic lobe). Clinically, the tumors presented as slow growing painless masses of long standing duration. Grossly, the tumors were well-circumscribed with firm, white to gray cut-off surface. Tumor size ranged from 1.2 to 4.0 cm in maximum diameter (average 3.0 cm). Microscopically, 2 cases were located in dermis, 4 cases were located in subcutaneous and 1 case was located in liver parenchyma. It was composed of spindle-shaped or stellate cells with a fibroblastic or myofibroblastic appearance, and sparsely scattered in densely fibrous or fibromyxoid background. There was small vascular component in tumor background. At high magnification, the tumor cells were medium size with abundant cytoplasm, and the nucleus were small and always with small nucleoli. In some cases, the tumor cells were slightly larger with enlarged nuclei, but without cellular atypical and mitosis. Immunohistochemical study showed that the tumor cells were strongly positive for vimentin, desmin, S-100 protein and CD34, but CKpan was negative. α-SMA showed focal positive in one case. Ki-67 index ranged from 1% to 2%. Four cases were followed-up (ranged from 11 to 21 months, average 16.5 months) and the patients had no recurrence after surgery. Conclusions: Desmoplastic firoblastoma is a rare soft benign tumor. The differential diagnosis includes other benign or low-grade fibroblastic/myofibroblastic lesions.

Clinicopathologic study of calcifying fibrous tumor of the gastrointestinal tract: a case series.

Calcifying fibrous tumor (CFT) is a rare benign mesenchymal lesion known to arise at multiple body sites that may clinically mimic other more aggressive lesions in the gastrointestinal (GI) tract. In this study we describe the clinicopathologic findings of 28 GI tract CFTs. Tumors predominantly arose in middle-aged adults with a slight female predominance. The most commonly involved sites were small bowel and colon, followed by stomach and appendix. Tumors ranged from 0.3 to 9.3 cm (median 1.4 cm), and submucosa was the most commonly involved layer. All tumors were well circumscribed and unencapsulated. Microscopically, tumors were hypocellular and composed of spindle cells with abundant, haphazardly arranged hyalinized collagen. No necrosis and less than one mitosis per 10 HPF were identified in all cases. Calcification was present in most (81%) of the cases. All cases had lymphoplasmacytic inflammatory infiltrates either scattered throughout the lesion with occasional perivascular conglomeration or in the form of lymphoid aggregates. A lymphoplasmacytic cuff was usually present (81%). Immunostains showed variable CD34 immunoreactivity and variable numbers of IgG4-positive plasma cells. The lesional cells were negative for DOG-1, ALK-1, S100, C-kit, Sox10, Melan A, HMB45, desmin, CK7, and CK20, and showed cytoplasmic staining for ß-catenin. Follow-up information was available in 5 cases with no recurrences reported to date (mean follow-up, 3 years). CFT is a rare benign tumor that can occur in part of the GI tract and should be distinguished from other mesenchymal tumors due to its low risk of recurrence.

[Clinicopathologic features of dermal nerve sheath myxoma and neurothekeoma: a comparative study].

Objective: To investigate the clinicopathologic characteristics and differential diagnosis of dermal nerve sheath myxoma (DNSM) and neurothekeoma (NTK). Methods: Clinical, pathological features and immunohistochemical profiles in 9 cases of DNSM and 8 cases of NTK were comparatively studied. The literature was reviewed. Results: The involved site of 9 DNSMs included the hand/fingers (n=3), ear (n=2), face, back, abdominal wall and waist (1 case each). Two of 8 NTKs arose in the forearm (n=2), one each in the nose, lip, shoulder, supraclavicular region, leg and hand. The most common presentation was a painless cutaneous nodule or plaque which grew slowly. Grossly, DNSM was often gelatinous, whereas NTK appeared relatively solid. Microscopically, both tumors were located in the dermis and/or subcutis. DNSM was composed of well-defined multiple lobules separated by fibrous septa. NTK also exhibited lobular or multinodular architecture, but was relatively ill-defined. Besides, fascicular or whorl-like arrangement was present in 3 cases of NTK. The lobules in DNSM consisted of a paucicellular proliferation of spindled, stellate and epithelioid cells forming interconnecting cords within abundant myxoid matrix. Small syncytial-like aggregates were readily noted. The constituted neoplastic cells in NTK were composed of ovoid to round epithelioid or histiocytoid cells. Scattered multinucleated giant cells were present in 2 cases. Based on the amount of myxoid matrix, 8 NTKs were further classified into cellular (5 cases), mixed (2 cases) and myxoid (1 case). By immunohistochemistry, neoplastic cells in DNSM were diffusely positive for S-100 protein, CD68, glial fibrillary acidic protein and SOX10, whereas neoplastic cells in NTK consistently expressed CD10 and microphthalmia transcription factor, with negativity for S-100 protein and SOX10. One patient each with DNSM and NTK experienced local recurrence due to incomplete excision. Conclusions: Although DNSM and NTK share clinical and pathological features, they belong to different entities. Whereas the former is consistent with a peripheral nerve sheath tumor, the latter is more akin to fibrous histiocytic tumor. Familiarity with their cliniopathologic characteristics and distinctive immunophenotypes will help distinguishing these two entities, as well as in the differential diagnosis of cutaneous neoplasms with similar features.

[About a case of calcifying fibrous tumor of the pleura]. / À propos d'un cas de tumeur calcifiante de la plèvre.

Calcifying fibrous tumor is a rare soft tissue benign tumor (OMS 2002). Some pleural localisations are described, which affect slightly older individuals than the other soft tissue forms. The calcifying fibrous tumor is included in the 2004 World Health Organization classification of pleural tumors. A pleural tumor located in the right inferior pulmonary lobe is diagnosed in a 59-year-old man. This pleural tumor is macroscopically well-circumscribed. Histologically, the rare spindle tumoral cells are located between bundles of a collagenous tissue, sometimes hyalinized, with psammomatous or dystrophic calcifications. The tumoral cells have a fibrohistiocytic origin. They stain positively for antibodies against vimentin, factor XIIIa, CD68, CD163, CD34. Antibodies against smooth muscle actin, desmin, PS100, ALK1 and EBV are negative. Main differencial diagnoses are other benign pleural tumors (solitary fibrous tumor, inflammatory myofibroblastique tumor), some malignant tumors (desmoplastic malignant pleural mesothelioma) and pleural pseudotumors (calcified pleural plaques, chronic fibrous pleuritis, amylose, hyalinizing granuloma). Our case is the 15th pleural calcifying fibrous tumor being reported.

Calcifying fibrous tumor: a case report.

Calcifying fibrous tumors are rarely seen and affect mostly children and young adults. A 21-year-old man presented with multiple palpable masses in the area from the right inguinal region to the anteromedial thigh. We performed a diagnostic excisional biopsy. Histopathologically, it was composed of fibroblasts, psammoma bodies, dystrophic calcifications and foci of mononuclear inflammatory cell infiltration in a collagenous dense stroma. We herein reported a case of calcifying fibrous tumor and discussed its clinical and morphological features with regard to the literature.

Pulmonary lipomatous hemangiopericytoma: report of a rare tumor and comparison with solitary fibrous tumor.

Lipomatous hemangiopericytoma is a rare mesenchymal tumor showing areas of lipid-containing cells admixed with a spindle-cell component. Like other hemangiopericytomas, it shows a similar vascular pattern to solitary fibrous tumor and, partly for this reason, it and other hemangiopericytomas have been subsumed into solitary fibrous tumor. The present study provides a comprehensive documentation of a single case of pulmonary lipomatous hemangiopericytoma of the lung, the first to be described at this site, and compares it with solitary fibrous tumor, in terms of clinical, histological, immunohistochemical, ultrastructural, and cytogenetic findings. Apart from the lipid-laden-cell component, pulmonary lipomatous hemangiopericytoma and solitary fibrous tumor were similar histologically. Bcl-2 was positive in both. CD34 was minimally expressed in pulmonary lipomatous hemangiopericytoma, which possessed some non-descriptive intercellular junctions, a feature shared by solitary fibrous tumor, which was CD34 positive. However, one of the latter was rich in gap junctions, a feature consistent with strong connexin (Cx) 43 staining and the existence, hitherto unappreciated, of a CD34/Cx43-positive tumor cell network. In pulmonary lipomatous hemangiopericytoma, chromosomal deletions of 43-44, X, -Y were found. In solitary fibrous tumor, 46, XY, del(13)(q?) abnormalities and abnormalities involving chromosome 10 were frequently observed. These similarities and differences are discussed in the context of the currently favored diagnostic fusion of hemangiopericytoma and solitary fibrous tumor.

Malignant solitary fibrous tumor originating from the peritoneum and review of the literature.

BACKGROUND: Solitary fibrous tumor (SFT) is a rare neoplasm frequently involving the pleura. Benign and malignant forms of the tumor occur, the benign variant being three to four times more common than the malignant. CASE REPORT: We present herein a rare case of large malignant solitary fibrous tumor (SFT) originating from the peritoneum. An abdominal computed tomography scan revealed a well-defined solid tumor with mixed density. An abdominal ultrasonography (US) revealed a well-circumscribed solid tumor containing a partially cystic lesion. T1-weighted abdominal magnetic resonance imaging demonstrated a hypo- to isointensity, which was a hypo- to hyperintensity on T2-weighted images. Liposarcoma originating from the retroperitoneum was suggested, and the patient underwent a complete resection of the tumor as well as the left kidney because tumor invasion of the upper left kidney was suspected. Immunohistochemically, the spindle-shaped cells were positive for CD34, and the diagnosis was SFT originating from the peritoneum. At the 14-month follow-up evaluation, no recurrence or metastasis was detected. CONCLUSIONS: This case gave us some difficulty, and the correct diagnosis of the peritoneal mass was valuable. To diagnose the malignant potential of this type of tumor accurately may have value to direct the appropriate therapeutic operations after surgery and postoperative progress observation.

Primary spindle cell lesions of the thyroid gland; an overview.

Spindle cell lesions of the thyroid gland (T-SCL) are not encountered routinely in clinical practice or in the context of thyroid pathology. They commonly are classified as primary or secondary to metastatic disease. Primary T-SCL can be derivedfromfollicular, C-cell (parafollicular), or mesenchymal components and may be the result of reactive or neoplastic processes, including post-fine-needle aspiration spindle cell nodules, Riedel thyroiditis, solitary fibrous tumor, leiomyoma, peripheral nerve sheath tumor, hyalinizing trabecular tumor, spindle epithelial tumor with thymus-like differentiation, follicular dendritic cell tumor, medullary carcinoma, papillary carcinoma, anaplastic carcinoma, sarcoma, squamous cell carcinoma, and carcinoma showing thymus-like differentiation. Because T-SCL may represent the expression of benign and highly malignant neoplasms, distinction among these processes is crucial because it dictates therapy and defines prognosis. The present article reviews the clinical, imaging, pathologic, and immunohistochemical characteristics of primary T-SCL.

[Solitary fibrous tumor: a clinico-morphological and immunohistochemical study].

Solitary fibrous tumor is a rare neoplasm which may occur at any site although it is more frequent in the pleura, mediastinum and lung. The study used 4 cases of tumor localization in the pleura and orbit. Three cases presented as a "hemangiopericytic" variety of spindle cells; there were numerous giant cells in orbit tumor. Solitary fibrous tumor revealed enhanced expression of vimentin, CD34, bel-2 and CD99. Expression of S-100, desmine and non-striated muscle actin was found in few cells in some cases. Such features as large size (over 10 cm), necrosis, high cellularity, nuclear polymorphism and high mitotic index (more than 4 mitoses within 4 visual fields, at high magnification) were used as malignancy criteria:. Tumor histological pattern of "hemangiopericytic" variety could be reliably identified thanks to immunohistochemical procedure.

Localized fibrous tumors (LFTs) of the pleura: clinical data, asbestos burden, and syntactic structure analysis applied to newly defined angiogenic/growth-regulatory effectors.

This study was performed to add clinical data, to introduce new markers, and to perform syntactic structural analysis on localized fibrous tumors (LFTs) of the pleura. The material comprised clinical data and processed sections obtained from 36 patients. The results achieved from quantitative imaging techniques and syntactic structure analysis were correlated with clinical data, including patients' habits (smoking), asbestos exposure, survival, and tumor recurrence. The disease caused increasing chest pain and dyspnea in 47% of patients. Exposure to asbestos was noted in 13 out of 36 patients, whereas smoking posed no major risk factor. Two patients developed a recurrent tumor after 8 and 42 months, respectively; none of the other patients died of this tumor disease within the follow-up period of maximal 212 months. The cases were clearly discriminated from mesotheliomas by the marker profile. Frequent expression of accessible ligands for endogenous lectins galectins-1 and -3, the expression of the angiogenic macrophage migration inhibitory factor (MIF), and the dense vascularization intimate a functional relationship. The proliferation index (Nv) was computed to be 1.6% in line with the balance of galectin expression. Abnormal p53 was expressed in only 19.4% of the cases. The diagnosis of LFT can be aided by quantitative assessment of vimentin, CD34, MIF, vascularization, and proliferation. Considering the galectin network, differential expression was noted with preference to effectors limiting growth and aggressiveness.

Malignant solitary fibrous tumor of the meninges.

Increasing numbers of solitary fibrous tumors (SFTs) in the meninges have been reported since this entity was first recognized. While most cases previously reported were considered to be benign, the malignant potential of extrathoracic SFTs has not been excluded. The authors report a rare case of a meningeal SFT with malignant behavior occurring in a Japanese female patient, initially resected when she was 44 years old and recurring in the same place four times during a 26-year follow-up period. A metastatic tumor to the right lung arose 25 years after the resection of the first meningeal tumor and focal invasion into the cerebellum was also observed with her last (5th) meningeal tumor. Immunohistochemical analysis showed all tumors to be diffusely positive for CD34 and negative for EMA, with a so-called "patternless" histological pattern, featuring thin collagen fibers between tumor cells. A focal "staghorn" vascular pattern was also observed. Ki67 (MIB-1) labeling indices and mitosis rates were 3.1+/-1.2% and less than 1/10 high power fields (HPF) in the first meningeal tumor and 16.1+/-6.4% and 6/10HPF in the last (5th) one, respectively. Thus, the present case suggests that meningeal SFTs possess malignant potential so that careful long-term follow up is required.

Clinical pathological analysis and immunohistochemical study of ten solitary fibrous tumors.

OBJECTIVE: To study the clinical and pathological characteristics of solitary fibrous tumor (SFT). METHODS: Clinical pathological analysis and immunohistochemical studies were performed on ten patients with SFT. RESULTS: The SFTs located variously and showed different histological features. All cases showed positive staining for CD(34), VM (vimentin) and Bcl-2, but negative staining for Desmin, S-100, CK (cytokeratin) and EMA (epithelial membrane antigen). CONCLUSIONS: SFT is described as a "patternless" growth pattern. According to clinical pathological features and immunohistochemistry, it is different from other soft tissue tumors. Long-term clinical follow-up is necessary for this kind of tumor.

Solitary fibrous tumor of the parotid gland: a case report.

The solitary fibrous tumor is traditionally associated with a mesothelial-lined surface. However, any organ with mesenchymal tissue has the potential for developing this tumor; therefore, it has been described in organs not associated with serosal surfaces. We report a case of solitary fibrous tumor of the parotid gland. Microscopically, the tumor showed a patternless arrangement of spindle cells in a fibrotic background and prominent vascular structures of varying size. Tumor cells showed a strong immunoreactivity for CD34 and bcl-2 antigens, but the tissue was negative for antibodies directed against actins, S-100 protein, and cytokeratins. One year after excision, the patient was alive and without evidence of disease.

Solitary fibrous tumour in the deep soft tissue of the neck in a Chinese man.

Originally described in the pleura, solitary fibrous tumour (SFT) is now reported in a variety of extrapleural sites. However, description of SFT in the deep soft tissue of the neck is very rare. In this report, we document the neoplasm, deep to the right platsyma muscle but superficial to the deep fascia just above the clavicle, in an otherwise well 50-year-old Chinese man. Histological examination of the excised specimen disclosed spindle-shaped cells disposed in short fascicles as well as randomly in association with areas of varying cellularity, keloidal hyalinisation of the stroma and haemangiopericytoma-like vessels. The tumour cells were CD34-, bcl-2- and CD99-positive. Since histological features may not accurately predict the biological behaviour of this tumour, careful long-term follow-up is advocated.

Intrarenal solitary fibrous tumor of the kidney report of a case with emphasis on the differential diagnosis in the wide spectrum of monomorphous spindle cell tumors of the kidney.

Solitary fibrous tumor (SFT) is a neoplasm that can occur in the urogenital tract, and is also reported occurring in the spermatic cord, seminal vesicles, urinary bladder, prostate, and kidney. Furthermore, it is most important to consider its existence in the kidney, because it is usually diagnosed as renal cell carcinoma pre-operatively. To our knowledge, only 10 cases of SFT have been reported in the kidney to date. We report the clinico-pathological features of an intrarenal SFT occurring in a 31-year-old woman. The tumor, measuring 8.6 cm in its greatest diameter, completely replaced the cortex and the medulla of the middle region of the right kidney, compressing the pelvis. Radiological imaging was consistent with a renal cell carcinoma. Histologically, the tumor was composed of a proliferation of bland-looking vimentin+, CD34+, bcl2+ and CD99+ spindle cells exhibiting a haphazard to storiform growth pattern, pushing borders, and a low mitotic rate (2 mitoses x 10 HPF). We placed emphasis on the differential diagnostic problems, i.e., its differentiation from other primary monomorphous benign and malignant spindle cell tumors of the kidney, such as fibroma, benign fibrous histiocytoma, hemangiopericytoma, inflammatory myofibroblastic (pseudo-)tumor, leiomyoma, angiomyolipoma with predominant spindle cell smooth muscle component, benign peripheral nerve sheath tumors, renal mixed epithelial/stromal tumors, adult type mesoblastic nephroma, fibrous type monophasic synovial sarcoma, malignant peripheral nerve sheath tumors, fibrosarcoma, and low-grade fibromyxoid sarcoma.