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Vascular Tumours

Pathology of Aneurysmal  Variant of Dermatofibroma (Aneurysmal Fibrous Histiocytoma)

Dr Sampurna Roy MD           


Path Quiz Case 24:  Case history and images:

Diagnosis: Aneurysmal Fibrous Histiocytoma




Aneurysmal fibrous histiocytoma differ from the classical cutaneous fibrous histiocytoma in both their clinical presentation and pathologic features.

Visit: Pathology of Fibrous Histiocytoma (Dermatofibroma)

Clinically, they may be larger than the usual cutaneous fibrous histiocytoma, are blue, black, or dark red, and have a cystic consistency.

They are most commonly located on the extremities and may be associated with  symptoms of pain and rapid growth.

The clinical diagnosis of fibrous histiocytoma is rarely considered in the differential diagnosis, which may include malignant melanoma, hemangioma, neurofibroma, and nonspecific cyst.

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Histopathology section of Aneurysmal Variant of Dermatofibroma

Histologically, the lesions are characterized by the presence of large, blood-filled tissue spaces.

Most cases show degree of epidermal hyperplasia, as seen in common fibrous  histiocytoma.

These spaces lack an endothelial lining, being surrounded and lined by histiocytes, many  of which contain hemosiderin pigment, fibroblasts, and foam cells.

The solid portions of the tumor have the usual features of a cutaneous fibrous histiocytoma

Despite the presence of prominent secondary changes due to haemorrhage, many cases show cellular polymorphism, hyalinized collagen bundles surrounded by tumour cells in the periphery of the lesion. 

Histopathology Image1 ; Image2 ; Image3 ; Image4 ; Image5 ; Image6


The tumour is usually positive for vimentin.

There is  rare focal smooth muscle actin positivity.

CD68 is positive in some reactive macrophages only.

Stains for CD31, CD34, desmin and factor XIIIa are usually negative.

Differential diagnosis:

1) The presence of extravasated erythrocytes in combination with a spindle-cell stroma may lead to an erroneous diagnosis of Kaposi's sarcoma. Kaposi's Sarcoma is positive for CD34  and lacks fibrohistiocytic cells.

2) Another important differential diagnosis is spindle cell angiosarcoma.

Spindle cells in aneurysmal  fibrous histiocytoma is negative for CD31 and CD34.

Some histiocytes may be CD31 positive.

3) Malignant melanoma is excluded due to absence of an overlying in-situ component. Immunohistochemistry reveals that S100 protein is negative.

Further reading:

Recurrent aneurysmal fibrous histiocytoma.

Aneurysmal fibrous histiocytoma showing transition from factor XIIIa-positive to -negative.

Aneurysmal and haemangiopericytoma-like fibrous histiocytoma. 

Aneurysmal fibrous histiocytoma of the skin. A histological, immuno- histochemical, and ultrastructural study.

Aneurysmal benign fibrous histiocytoma: clinicopathological analysis of 40 cases of a tumour frequently misdiagnosed as a vascular neoplasm. 

Aneurysmal ("angiomatoid") fibrous histiocytoma of the skin.

Aneurysmal and haemangiopericytoma-like fibrous histiocytoma




Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)



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