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2009
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Giant cell angiofibroma was introduced as an entity by Dei Tos et al. in 1995. It is a rare mesenchymal neoplasm most commonly arising in the soft tissues near the orbit. Age Middle-aged patients. Site: Orbit or eyelid and in extraorbital sites. Extraorbital sites include- head and neck region (may occur in the nasolacrimal duct and lacrimal sac region), back , axilla, hip, vulva, inguinal region, mediastinum & retroperitoneum . In males this lesion is common in the orbit and in females it usually occurs in the extraorbital sites. Macroscopic features: Well circumscribed lesion which may be encapsulated. Cut surface has a greyish white appearance. In some cases the cut surface may have a lymphangioma-like cystic appearance. Microscopic features: According to some authors the histological features are intermediate between giant cell fibroblastoma and solitary fibrous tumour . Histologically, the tumour is composed of a mixture of cytologically bland spindle-shaped cells and ovoid cells of varying cellularity. The spindled tumour cells have large, rounded nuclei, sometimes with complex folded shape and pseudoinclusions. The cells are set in a variably collagenous and myxoid stroma. There are prominent, various-sized blood vessels, often with perivascular hyalinization. Pseudovascular angiectoid spaces are present filled with an amorphous eosinophilic material. These are partly lined by multi- or mononuclear giant cells. Rare multinucleated floret-like giant cells are seen. Other features: Keloidal collagen deposition ; staghorn pericytomatous vascular spaces, similar to those seen in solitary fibrous tumour, clusters of adipocytes- resembling lipomatous hemangiopericytoma ; presence of mitotic figures (ranged from 1 to 3 mitoses/10 high-power fields).
Immunohistochemistry: Immunohistochemically, the mononuclear and multinucleated cells within these tumours are positive for vimentin and CD34 .CD99 is positive,bcl-2 is variably positive.Tumour cells are also negative for other antigens, including Factor VIII-related antigen, desmin, alpha smooth muscle actin, myoglobin, S-100 protein, LeuM1, lysozyme, alpha-1-antitrypsin and cytokeratins (AE1/AE3 and CAM5.2).Cytogenetics: In a case of giant cell angiofibroma, abnormalities of chromosome 6 with a common pattern involving 6q13 were detected.Differential diagnosis: Orbital lesion- Solitary fibrous tumour Extra-orbital lesion- Giant cell fibroblastoma ; Deep fibrous histiocytoma ; Synovial sarcoma ; Schwannoma ; Malignant fibrous histiocytoma ; Haemangiopericytoma ; Fibrosarcoma ; Other tumours containing osteoclast like giant cells ( In GCA - CD68 is negative).
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