Pathology of Giant Cell Angiofibroma - Infographic

Dr Sampurna Roy MD               2022

Giant cell angiofibroma was introduced as an entity by Dei Tos et al. in 1995.

Giant cell angiofibroma : A soft tissue tumour with Floret-like giant cells [Pathology Infographic]

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 and 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 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 ; Haemangiopericytoma ; Fibrosarcoma ; Other tumours containing osteoclast like giant cells ( In GCA - CD68 is negative).