Prognostic analysis of extrameningeal solitary fibrous tumor using the modified Demicco model: a clinicopathologic study of 111 Chinese cases.

Introduction: Solitary fibrous tumor (SFT) represents a fibroblastic neoplasm exhibiting NAB2::STAT6 gene rearrangement, displaying diverse clinical manifestations, spanning from benign to malignant. To predict prognosis, the modified (four-variable) Demicco (mDemicco) model was introduced. This investigation aims to authenticate the mDemicco risk model's precision in Asian patients while investigating the clinicopathological and molecular factors linked to the prognosis of extrameningeal SFTs. Methods: Clinicopathological data from 111 extrameningeal SFT cases in East China, covering the period from 2010 to 2020, were thoroughly analyzed. The tumors were classified using the mDemicco model. Immunohistochemical evaluation of P16 and P53, molecular detection of TP53 and TERT promoter mutation, and fluorescence in situ hybridization for CDKN2A gene alterations were performed. Statistical methods were utilized to assess the associations between clinicopathological or molecular factors and prognosis. Results: Histologically, only one parameter, the mitotic count, exhibited a statistical correlation with progression-free survival (PFS) and overall survival (OS). During the Kaplan-Meier analysis, the variation in PFS among the different risk groups exhibited a notable trend towards statistical significance. Nevertheless, 3 out of 74 patients classified as low-risk SFTs and 7 out of 21 patients classified as intermediate-risk exhibited disease progression. Among the 5 patients with TP53 mutations and/or mutant-type P53 immunophenotype, 3 experienced disease progression, including 2 intermediate-risk patients. Additionally, among the 4 patients with TERT promoter mutations who were followed up, 3 showed progression, including 2 intermediate-risk patients. Moreover, it was observed that hemizygous loss of CDKN2A was detected in more than 30% of one case, yet the patient exhibited a favorable survival outcome. Conclusion: The mDemicco risk model exhibits certain limitations when dealing with smaller tumor sizes, younger age groups, and occurrences of malignant and dedifferentiated SFTs. Furthermore, molecular factors, such as TP53 or TERT promoter mutations, may identify intermediate-risk SFTs with poorer prognoses.

Case report: ALK-rearranged spindle and epithelioid cell neoplasms with S100 and CD34 co-expression: Additional evidence of kinase fusion-positive soft tissue tumors.

ALK rearrangements have rarely been reported in S100- and CD34-co-expressing soft tissue neoplasms with lipofibromatosis-like neural tumor (LPFNT) pattern or stromal and perivascular hyalinization, mimicking NTRK-rearranged spindle cell tumors. Here, we reported ALK fusions involving related partner genes in two adult soft tissue tumors with S100 and CD34 co-expression, and conducted a literature review of mesenchymal tumors harboring ALK or other kinase fusions. Case 1 was a 25-year-old female who underwent excision of a soft tissue mass in the anterior thigh region. Morphologically, the tumor was composed of spindle cells adjacent to epithelioid cells embedded in myxedematous and hyalinized stroma, with infiltrative boundary. Spindle cells mixed with inflammatory infiltration resembling inflammatory myofibroblastic tumor (IMT) were seen sporadically. However, brisk mitosis and focal necrosis was also observed, indicating an intermediate-grade sarcoma. In case 2, the left side of the neck of a 34-year-old man was affected. The tumor was composed of monomorphic spindle cells arranged in fascicular growth or patternless pattern, with stromal and perivascular hyalinization. Sparse inflammatory cell infiltration was also observed. Both tumors showed CD34, S100, and ALK-D5F3 immunoreactivity. Next generation sequencing (NGS) test identified a PLEKHH2::ALK fusion in case 1, which was confirmed by RT-PCR and Sanger sequencing, whereas the RT-PCR (ARMS method) test detected an EML4::ALK fusion in case 2. In conclusion, this study expands the morphological and genetic landscape of tumors with S100 and CD34 co-expression harboring kinase fusions, and suggests that kinase fusion-positive mesenchymal neoplasms are becoming an enlarging entity with a variety of morphological patterns.

Inflammatory myofibroblastic tumor arising from soft tissues of extremities harboring a novel CLIP2-ALK fusion.

A 34-year-old Chinese woman found a lump in her left leg for more than 3 weeks without any discomfort. Grossly, the tumor was relatively well delineated with focal infiltration. Histopathologic evaluation showed a compact fascicular spindle cell proliferation with variable myxoid and collagenous stroma and scattered inflammatory infiltrate. Immunohistochemically, the tumor cells showed positive expression of ALKD5F3 and SMA and negative expression of CD34, desmin, and cytokeretin. Fluorescence in situ hybridization analysis of the ALK locus showed break-apart signals in 20% of tumor cells, and DNA sequencing discovered a novel CLIP2-ALK fusion gene. The lesion was diagnosed as an inflammatory myofibroblastic tumor (IMT). To the best of our knowledge, this is the first case with CLIP2-ALK gene fusion in the somatic soft tissue IMTs.

A low-grade malignant soft tissue tumor with S100 and CD34 co-expression showing novel CDC42SE2-BRAF fusion with distinct features.

Recently, a novel group of spindle cell tumors defined by S100 and CD34 co-expression harboring recurrent fusions involving RET, RAF1, BRAF, and NTRK1/2 gene has been identified. Morphologically, they are characterized by monomorphic neoplasm cells, "patternless" growth pattern, stromal, and perivascular hyalinization, lacked necrosis. We reported a 52-year-old Chinese female patient with a S100 and CD34 co-expression sarcoma presenting in the right proximal forearm. The forearm mass initially emerged 19 months ago when it was misdiagnosed as a solitary fibrous tumor and was surgically removed without further treatment. Microscopically, the primary and the recurred tumors share the same features, resembling the morphology of the recently characterized group. Nevertheless, some distinct features, such as predominantly epithelioid tumor cells and focally staghorn vessels, were also present in our case. Genomic profiling with clinical next-generation sequencing was performed and revealed CDC42SE2-BRAF gene fusion, MET amplification, and CDKN2A/B deletion. Both FISH and nested RT-PCR were performed to confirm the gene fusion. The patient was treated with crizotinib for two cycles but showed no obvious benefit. The presented case adds to the spectrum of the novel, characterized solid tumors, and provides suggestions for emerging therapeutic strategies for precision medicine involving targeted kinase inhibitors.

[Epithelioid hemangioma: a clinicopathologic analysis of 7 cases].

OBJECTIVE: To study the clinicopathologic features, diagnosis and differential diagnosis of epithelioid hemangioma. METHODS: The morphologic features of 7 cases of epithelioid hemangioma of skin, bone and venous vessels were studied. RESULTS: There were altogether 4 male and 3 female patients (median age = 34 years; age range from 14 to 54 years). The 3 skin cases presented as single or multiple erythematous to bluish nodules or papules, with or without itchiness. The 2 bone cases appeared as osteolytic expansile lesions on radiologic examination. The remaining 2 cases involved medium-sized venous structures and presented as small isolated nodules in soft tissue. Histologically, the lesions were characterized by the presence of exuberant endothelial proliferations with various degree of inflammatory reaction. The neoplastic endothelial cells were plump, eosinophilic and polygonal, forming vascular channels. Occasional solid sheet-like arrangement was demonstrated. Intracytoplasmic vacuoles were commonly identified, indicating formation of primary lumen. The surrounding stroma contained various number of eosinophils and lymphoplasmacytic cells. Immunohistochemical study showed that the tumor cells were positive for endothelial markers (CD31 and CD34) and negative for epithelial marker (cytokeratin). Follow-up information was available in 6 cases. The duration of follow-up ranged from 5 to 36 months (median = 14 months). There was no evidence of recurrence or distant metastasis. CONCLUSIONS: Epithelioid hemangioma is a rare benign curable lesion which can be multifocal, involving skin, soft tissue and bone. It needs to be distinguished from Kimura's disease and epithelioid hemangioendothelioma.

[Solid variant of angiomatoid fibrous histocytoma:report of 3 cases].

OBJECTIVE: To study the clinicopathologic features, immunophenotype, molecular genetics and differential diagnosis of solid variant of angiomatoid fibrous histocytoma. METHODS: The clinicopathologic features of 3 cases of solid variant of angiomatoid fibrous histocytoma were analyzed and the literature was reviewed. RESULTS: There were a total of 2 males and 1 female. The age of patients ranged from 9 to 12 years. The patients presented with a painless mass located in left forearm, left knee or back. The lesions were treated by complete surgical resection. On gross examination, the tumors varied from 1.6 cm to 4.5 cm in greatest dimension. They were well-circumscribed and had pale yellow to grayish-red solid cut surface. Histologically, the tumor was composed of histocytoid cells arranged in sheet-like pattern. A fibrous pseudocapsule surrounded by lymphocytes and plasma cells was identified. Immunohistochemical study showed that the tumor cells in all cases were positive for vimentin and CD68. They were negative for S100 protein, cytokeratin, CD34, CD31, smooth muscle actin, CD35, CD21 and CD30. Two cases also expressed CD99 and one of them was positive for desmin and epithelial membrane antigen. Fluorescence in-situ hybridization was positive for EWSR1 gene. CONCLUSIONS: Solid type represents a variant of angiomatoid fibrous histocytoma and is considered as tumor of borderline malignant potential. Definitive diagnosis requires thorough histologic examination and clinical correlation. Immunohistochemistry and EWSR1 gene study are helpful in further delineation and differential diagnosis. Complete resection or wide local excision with post-operative follow up is the main modality of treatment.

CD25 is a novel marker of hepatic bile canaliculus.

OBJECTIVE: Although many antigens have been investigated, the method for the bile canaliculus staining using optical microscopy needs to be improved. The aim of the present study was to assess the expression pattern of a candidate marker, CD25, in normal and diseased liver tissue. METHODS: Immunohistochemistry, immunofluorescence, and immune electron microscopy assays were performed with 41 liver sections and 2 different anti-CD25 monoclonal antibodies. A polyclonal antibody against carcinoembryonic antigen (CEA) was also used to stain bile canaliculus as a control. CD25 expression levels in normal and diseased liver tissue were also determined. RESULTS: CD25 was predominantly localized at the bile canaliculus of adult and infantile liver, evidenced by both immunohistochemistry and immunofluorescence assays. The electron microscopy assay showed that there were obvious amorphous electron-dense deposits at the bile canaliculus. In contrast, the CEA-positive area included bile canaliculus as well as basolateral aspects of hepatocytes. CD25 expression levels did not differ significantly among different disease states. CONCLUSION: This study provides the first evidence that CD25 is a novel marker of bile canaliculus. Characteristics of CD25 expression may shed light on immunohistochemistry and immunofluorescence analysis of bile canaliculus in both basic and clinical hepatic investigations.

[Primary intermediate hemangioendothelioma of bone: a study of 5 cases].

OBJECTIVE: To study the radiologic and pathologic features of primary intermediate hemangioendothelioma of the bone. METHODS: Five cases of primary intermediate hemangioendothelioma of bone encountered in the past three years were enrolled into the study. The clinical, radiologic, pathologic and immunohistochemical features of the tumors were reviewed. RESULTS: The patients included 3 children with Kaposiform hemangioendothelioma and 2 elderly with retiform hemangioendothelioma. Four of the cases affected long bones and the remaining case affected the clavicle. One case showed multifocal involvement of the humerus. Radiologically, the tumors showed borderline to low-grade bony destruction, with various degrees of cortical defect. Intralesional or perilesional bone formation was demonstrated in 4 cases and radial spicules were seen in 1 case. The histopathologic features of primary intermediate hemangioendothelioma of bone were similar to those of soft tissue, except for the presence of reactive bone formation. Immunohistochemically, the tumor cells were positive for CD31 (5/5), CD34 (5/5), vimentin (5/5) and smooth muscle actin (3/5) but negative for cytokeratin and epithelial membrane antigen. CONCLUSIONS: Primary intermediate hemangioendothelioma of bone is a distinct entity and similar histologic classification applies as in its soft tissue counterparts. Comparison of the biologic behavior requires long-term follow-up studies.

[Adult prostate sarcoma: a clinicopathologic study of 15 cases].

OBJECTIVE: To clarify the clinical and morphological features of adult prostate sarcoma (APS) and to further improve the knowledge and diagnostic accuracy for APS. METHODS: Fifteen cases of APS were observed and analyzed on the clinical symptom, pathological features, treatment and prognosis. RESULTS: Age of onset ranged from 22 to 77 years (mean 46.3 years). The majority of cases were presented with dysuresia. By digital rectal examination and imaging of the prostate, APS was often identified as a large tumor mass. There were 6 cases of leiomyosarcomas, 6 embryonal rhabdomyosarcomas, and 3 fibrosarcomas in this series. Follow-up data were available for 12 cases: 7 cases died of the disease between 9 days and 360 days after surgery. Among 5 survived patients, 3 cases had recurrence after 2 to 24 months follow-up. CONCLUSIONS: APS is a rare tumor that typically has clinical features: earlier age of onset, fast-appeared urinary tract symptoms, significant mass effects, and poor outcome. Level of prostate specific antigen (PSA) is usually normal or lower. Final diagnosis relies on the features of histology and immunohistochemistry expression profile.

[EZH2 expression in human prostate cancer and its clinicopathologic significance].

OBJECTIVE: To investigate the expressions of the EZH2 protein and EZH2 mRNA in human prostate cancer (PCa) and their correlation with the clinicopathologic parameters. METHODS: A tissue microarray (TMA) was constructed, which contained 48 dots of formalin-fixed paraffin-embedded tissue samples of human PCa. The expressions of the EZH2 protein and EZH2 mRNA in the samples were detected by immunohistochemistry (EnVision) and in situ hybridization (ISH). Another 15 cases of human benign prostate hyperplasia (BPH) and 12 cases of human prostate intraepithelial neoplasia (HGPIN) were taken as controls. RESULTS: The positive rates of the EZH2 protein and mRNA were significantly higher in PCa than in BPH and HGPIN (87.5% vs 13.33% and 16.67%, 81.25% vs 6.67% and 16.67%, P < 0.05). The positive expression of the EZH2 protein was 96.67% and 72.22% in the Gleason score > or = 7 and Gleason score < or = 6 groups, respectively, with significant differences between the two groups (P < 0.05). The positivity of the EZH2 protein was significantly related to the TNM stage, increasing with tumor progression (P < 0.05), but not to age and serum PSA (P > 0.05), and so was that of EZH2 mRNA to TNM stage (P < 0.05), but not to age, serum PSA and Gleason score (P > 0.05). When the above characteristics were regarded as two-level discrete variables, both the EZH2 protein and EZH2 mRNA showed statistically significant differences in the positive expression rate (P < 0.05). CONCLUSION: The over-expressions of the EZH2 protein and EZH2 mRNA may play an important role in the pathogenesis and progression of PCa and provide some reference indexes for estimating the malignancy, progression and prognosis of PCa.