Orbital solitary fibrous tumors: a multi-centered histopathological and immunohistochemical analysis with radiological description.

BACKGROUND: Solitary fibrous tumors (SFT), formerly called hemangiopericytoma, are rare tumors derived from mesenchymal cells originally described in the pleura, but these tumors may affect extraserosal tissues including the lacrimal gland and orbit. OBJECTIVE: Conduct a multi-centered clinical, radiological and histopathological analysis of 17 orbital SFT cases. DESIGN: A retrospective case series. SETTING: Three eye centers in two countries. PATIENTS AND METHODS: The data collected from the charts of 17 adult patients presenting with tissue diagnosis of orbital hemangiopericytoma or SFT from January 2003 to December 2018 included demographics, clinical imaging and histopathological information including immunohistochemical (IHC) characteristics. MAIN OUTCOME MEASURES: The demographic characteristics, clinical presentation, and histopathological patterns or variants of SFT were analyzed. SAMPLE SIZE: 17 adult patients. RESULTS: Mean age was 45 years (range 23-80 years). Male to female ratio was 3:1. The right eye was affected in 12 (70.5%) patients. Commonest presentation was proptosis in 13/17 (76% of patients). Other symptoms were impaired motility (29%) and ptosis (11%). Lesions mostly affected the medial orbit (35%), then orbital apex in 11%. The histopathological classic pattern-less variant was the commonest. One case with aggressive behavior, multiple recurrences and atypical features was encountered. Immunohistochemical (IHC) markers used included CD34 expression in all cases, Bcl-2 expression in 10/11, CD99 in 9/9 and Vimentin in 4/4. STAT6 was used in 2 cases. CONCLUSIONS: SFTs are rare tumors affecting the orbit in both genders equally in their mid-forties, but showed male predominance in our analysis with a predominant classic histopathological pattern. Tissue diagnosis is essential and requires IHC studies for confirmation. LIMITATIONS: Sample size is relatively small owing to the rarity of this tumor in the orbit. CONFLICT OF INTEREST: None.

[Extraovarian granulosa cell tumor with FOXL2 mutation. Morphological and immunohistochemical differential diagnosis]. / Tumor de células de la granulosa extraovárico con mutación FOXL2. Diagnóstico diferencial morfológico e inmunohistoquímico.

Extraovarian granulosa cell tumor is a very uncommon tumor and the identification of a recurrent mutation in FOXL2 may be used as another diagnostic tool along with the classical morphological and immunohistochemical findings. Here, we report a new case of extraovarian granulosa cell tumor in a 57 years old female patient presented with a sub-hepatic mass and abdominal pain. Histopathological examination of the excised mass showed features of adult-type granulosa cell tumor with α-inhibin, calretinin, WT1, S100, CD99 and progesterone receptor immunoreactivity. A FOXL2 mutation was detected on molecular biology study. A final diagnosis was an extraovarian adult-type granulosa cell tumor. We discuss the histopathological and immunohistochemical differential diagnosis.

Ewing sarcoma with myxoid stroma: Case report of an unusual histological variant.

We describe the case of a Ewing sarcoma with prominent myxoid stroma of the temporal bone in a 26-year-old female. Histologically, the tumor exhibited a fascicular growth pattern of round to spindled cells with a minimal amount of pale eosinophilic to clear cytoplasm and oval or spindled nuclei with finely dispersed chromatin and small nucleoli. Myxoid changes were prominent (>50%), with reticular or pseudoacinar growth of the loosely cohesive cells. The tumor showed strong expression of CD99, FLI1, and CD56 and was positive for the EWSR1-FLI1 fusion transcript. The diagnosis of Ewing sarcoma with myxoid stroma (myxoid variant) is particularly problematic owing to the large number of potential mimics. The tumor extends the morphologic spectrum of Ewing sarcoma beyond the previously described histological variants, and broadens the differential diagnosis. For any round/spindle cell sarcoma, prominent myxoid stroma and CD99 immunoreactivity should prompt consideration for molecular studies that include analysis of both EWSR1 and FLI1.

A CD99+ primary spinal central PNET in a pregnant patient- therapeutic concerns and issues.

Spinal tumours in pregnancy are rare. Spinal tumours account for only 10-15% of all primary central nervous system (CNS) tumours. Most spinal tumours in pregnant women have been described as meningiomas or vascular tumours. We present the unique case of a pregnant patient presenting with a CD 99+ primary spinal central PNET.

[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.

Ewing sarcoma.

Ewing sarcoma is the second most frequent bone tumour of childhood and adolescence that can also arise in soft tissue. Ewing sarcoma is a highly aggressive cancer, with a survival of 70-80% for patients with standard-risk and localized disease and ~30% for those with metastatic disease. Treatment comprises local surgery, radiotherapy and polychemotherapy, which are associated with acute and chronic adverse effects that may compromise quality of life in survivors. Histologically, Ewing sarcomas are composed of small round cells expressing high levels of CD99. Genetically, they are characterized by balanced chromosomal translocations in which a member of the FET gene family is fused with an ETS transcription factor, with the most common fusion being EWSR1-FLI1 (85% of cases). Ewing sarcoma breakpoint region 1 protein (EWSR1)-Friend leukaemia integration 1 transcription factor (FLI1) is a tumour-specific chimeric transcription factor (EWSR1-FLI1) with neomorphic effects that massively rewires the transcriptome. Additionally, EWSR1-FLI1 reprogrammes the epigenome by inducing de novo enhancers at GGAA microsatellites and by altering the state of gene regulatory elements, creating a unique epigenetic signature. Additional mutations at diagnosis are rare and mainly involve STAG2, TP53 and CDKN2A deletions. Emerging studies on the molecular mechanisms of Ewing sarcoma hold promise for improvements in early detection, disease monitoring, lower treatment-related toxicity, overall survival and quality of life.

[Solitary fibrous tumor/hemangiopericytoma of central nervous system: a clinicopathologic analysis of 71 cases].

Objective: As solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) share the same molecular genetics features, the 2016 WHO classification of central nervous system (CNS) tumors had created the combined term SFT/HPC and assigns three grades. This study aims to investigate the clinicopathologic characteristics, diagnosis, differential diagnosis and prognosis of CNS SFT/HPC. Methods: Seventy-one cases of CNS SFT and HPC were retrospectively reclassified and studied. Histopathological, immunohistochemical and imaging features were analyzed. The follow-up data were analyzed. Results: There were 37 male and 34 female patients. The median age was 48 years (range, 3-77 years). Twelve cases (17%) were WHO grade Ⅰ, 26 (37%) were WHO grade Ⅱ and 33 (46%) were WHO grade Ⅲ. Microscopically the tumor could show traditional SFT phenotype, HPC phenotype or mixed phenotype. Immunochemically, 97%(69/71) were positive for STAT6, with 96%(66/69)showing diffuse strong staining. Approximately 90% were diffusely positive for bcl-2, CD99 and vimentin. The expression rate of CD34 decreased with increasing tumor grade, and the mean expression rate was 78%. SSTR2a was variably expressed in 10% (7/71) of cases including one case showing strong cytoplasmic staining. A few cases expressed EMA, CD57 and S-100 focally. The Ki-67 index ranged from 1% to 50%. Thirty four patients were followed up for 8-130 months; 12 patients(35%)had recurrences, and two (6%) had liver metastases. Conclusions: CNS SFT/HPC is relatively uncommon. There was significant morphological overlap or transition between different grades. STAT6 is a specific marker for the diagnosis of this tumor. Surgical resection is the preferred treatment. WHO grade Ⅱ and Ⅲ SFT/HPC show rates of local recurrence and systemic metastasis, with liver being the most common site of extracranial metastasis.

Extraskeletal mesenchymal chondrosarcoma at unusual location involving spleen and kidney with review of literature.

Mesenchymal chondrosarcoma (MC) is a rare malignant neoplasm bearing characteristic dimorphic pattern histologically. We describe two rare cases of primary MC involving two different visceral organs (1) a 24-year-old man with solid renal mass and, (2) a 42-year-old man with cystic splenic mass. The histological and immunophenotypical features of both lesions were classical of MC. Although this lesion is uncommon in visceral organs, the possibility of this rare entity must be kept in differential diagnosis with compatible morphology.

Ewing sarcoma: a chronicle of molecular pathogenesis.

Sarcomas have traditionally been classified according to their chromosomal alterations regardless of whether they accompany simple or complex genetic changes. Ewing sarcoma, a classic small round cell bone tumor, is a well-known mesenchymal malignancy that results from simple sarcoma-specific genetic alterations. The genetic alterations are translocations between genes of the TET/FET family (TLS/FUS, EWSR1, and TAF15) and genes of the E26 transformation-specific (ETS) family. In this review, we intend to summarize a chronicle of molecular findings of Ewing sarcoma including recent advances and explain resultant molecular pathogenesis.

Utility of CD99 Paranuclear Expression in the Differential Diagnosis of Merkel Cell Carcinoma.

BACKGROUND: Recent reviews have referred to the paranuclear dot-like staining pattern of CD99 in several neoplasms, including solid pseudopapillary tumors in the pancreas, colonic adenocarcinomas, and colonic adenomas as well as in Merkel cell carcinoma (MCC). The aim of this work was to explore the utility of CD99 paranuclear staining in the differential diagnosis of MCC. MATERIAL AND METHODS: We explore paranuclear dot-like CD99 expression in several small, round blue cell neoplasms, including neuroendocrine neoplasms, Ewing sarcomas/primitive neuroectodermal tumors (EWS/PNET), melanomas, small cell lung carcinomas (SCC), lymphoblastic lymphoma/leukemia, and rhabdomyosarcomas, in comparison with 33 cases of MCC, to determine the specificity of the paranuclear dot-like CD99 expression in MCC. RESULTS: Twenty MCC (60%) demonstrated focal expression of CD99 and of those, 14 (42.4%) showed the characteristic paranuclear dot-like expression. CD99 was also paranuclear positive in 4 of 11 (36%) SCC, in 3 of 7 (43%) EWS/PNET, in 1 of 6 (16%) lymphoblastic lymphoma/leukemia cases, in 3 of 3 (100%) rhabdomyosarcomas and all melanomas were negative for the CD99 reaction. CONCLUSION: CD99 paranuclear dot-like expression was not exclusive of the MCC compared with several neoplasms included in its differential diagnosis. This expression is not a great diagnostic aid.

[Significance of P504s in distinction between solid pseudopapillary tumor of pancreas and pancreatic neuroendocrine tumors].

OBJECTIVE: To study the significance of P504s in differential diagnosis between solid pseudopapillary tumor of the pancreas (SPTP) and pancreatic neuroendocrine tumors (PanNET). METHODS: Forty-three patients with SPTP and 41 patients with PanNET encountered during the period from 2007 to 2014 were recruited. Immunohistochemical study for vimentin, CD10, chromogranin A, synaptophysin, beta-catenin, CD99 and P504s in SPTP and PanNET was performed. The diagnostic value of P504s in differentiating SPTP from PanNET was analyzed. RESULTS: Immunohistochemical study showed that vimentin, CD10, chromogranin A, synaptophysin and CD99 were expressed both in SPTP and PanNET. All cases of SPTP showed granular cytoplasmic expression of P504s, whereas those of PanNET were negative. CONCLUSION: P504s is a sensitive and useful marker for SPTP and can be used in the distinction between SPTP and PanNET.