Angiomatoid fibrous histiocytoma is a neoplasm of intermediate biologic potential most often arising in the extremities of children and young adults. Its rarity may lead to misdiagnosis as either a reactive lesion or a benign or higher-grade tumor. Originally described as a type of malignant fibrous histiocytoma, its differentiation remains enigmatic, with precise histogenesis still only hypothesized. Its morphology is distinct, as a circumscribed lesion with sheets of bland spindle to ovoid cells, peripheral lymphoplasmacytic infiltrate, and blood-filled cystic cavities, and half of the cases show strong desmin expression. Cytogenetically, 2 specific translocations, t(12:16)(q13:p11) and more recently t(12:22)(q13:q12), have been characterized. The literature on angiomatoid fibrous histiocytoma is reviewed, particularly with regard to recent molecular genetic developments and differentiation, and its morphology, immunohistochemistry, and differential diagnosis are summarized.
"Within a small percentage of AFHs other muscle markers such as HHF-35 and calponin also stain positive . The AFH in the present case report showed positive staining for CD99 and EMA, though desmin seemed positive only in the surrounding capillary epithelium and CD68 in the intralesional dendrites. "
[Show abstract][Hide abstract] ABSTRACT: Angiomatoid fibrous histiocytoma is an uncommon soft-tissue tumor of intermediate malignancy that is often misdiagnosed initially. As there is not one immunohistochemical marker that consequently stains positive or negative for angiomatoid fibrous histiocytoma, molecular diagnostics are becoming more widely used. So far three translocations have been reported to arise in angiomatoid fibrous histiocytoma: FUS-ATF1, EWSR1-CREB1, or EWSR1-ATF1. We present a case of angiomatoid fibrous histiocytoma on the upper arm of a 40-year-old female, which was initially misdiagnosed as metastatic melanoma in a lymph node. Revision of the pathology revealed an angiomatoid fibrous histiocytoma, which was later confirmed by a EWSR1-CREB1 translocation with molecular diagnostics. Furthermore, we review the relevant literature and provide an overview of all available case reports in the past ten years. This case report illustrates the importance for pathologists of knowing the typical pathology features of AFH and integrating immunohistochemical and molecular findings in order to prevent overdiagnosis of lymph node metastasis of a malignancy.
"Histological differential diagnosis mainly involves other vascular neoplasms accompanying giant cell proliferation, such as giant cell fibroblastoma , angiomatoid fibrous histiocytoma , plexiform fibrohistiocytic tumor [7,9]. The giant cells in Giant cell fibroblastoma are characteristically located in the inner-side of the cranny-like vasculature and CD34-positive, which is different from GCAB. "
[Show abstract][Hide abstract] ABSTRACT: Giant cell angioblastoma (GCAB) is an extremely rare soft tissue tumor of early childhood and only five cases have been described to date. As such the clinical, pathological, and prognostic features are poorly defined. We prensent here a new case of GCAB in bone of a child aged 4-years old. The lesion was composed of dense and loose cell regions. The dense regions were characterized by nodular, linear, and plexiform aggregates of oval- to spindle-shaped tumor cells around small vascular channels and interspersed with large mononuclear cells and multinucleate giant cells. The loose cell areas were characterized by distributed fibroblasts and abundant myxoid matrix, which diminished with patient age. Infiltrative growth was observed in some areas. Oval-to-spindle cells showed positivity for Vimentin, CD31 and CD34 staining, and partial positivity for smooth muscle actin. Mononuclear cells and multinucleate giant cells showed Vimentin and CD68 positivity. Seventeen months after thorough curettage of the lesion, a local recurrence was found. Based upon the clinical, histological and immunohistochemical findings, infiltrate condition, and prognosis, we classified GCAB into two subtypes. Type I does not infiltrate surrounding tissues and has good prognosis. Type II infiltrates the surrounding tissues, relapses earlier, and has worse prognosis. This report augments the limited GCAB literature to promote our understanding and guide therapy of this rare disease.
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[Show abstract][Hide abstract] ABSTRACT: Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor of low malignant potential. The tumor is mostly seen in the deep dermis and subcutis of the lower extremities in children and young adults. Histologically, the tumor forms lobulated sheets of plump round to spindle cells surrounded by a fibrous pseudocapsule and lymphoid cuff. The cytogenetic and molecular hallmarks of AFH are not well defined. Only 4 of 30 reported cases of AFH have had karyotypic information. We present a case of AFH in the inguinal region of a 12-year-old girl. The tumor showed characteristic histological features, t(2;22)(q33;q12.2), and EWSR gene rearrangement by fluorescence in situ hybridization.
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