Aneurysmal benign fibrous histiocytoma with atrophic features

Abstract

Aneurysmal benign fibrous histiocytoma is an uncommon pathologic variant of dermatofibroma. In addition to the features of a typical dermatofibroma, it has large cleft-like or cavernous blood-filled spaces with numerous hemosiderin pigments. It should be differentiated from angiomatoid malignant fibrous histiocytoma, malignant melanoma, and vascular tumors such as Kaposi's sarcoma and angiosarcoma. Atrophic dermatofibroma is also a rare variant of dermatofibroma, and the combination of aneurysmal and atrophic features is rarer still. We report a case of aneurysmal benign fibrous histiocytoma with atrophic features in a 27-year-old male who had a grayish-brown atrophic patchy lesion on his back for 2 years.

Keywords: Aneurysmal variant; Atrophy; Dermatofibroma.

Fig. 1

A non-tender, fingernail-sized, grayish-brown, atrophic, shiny patch on the upper back.

Fig. 2

(A) Histopathological findings revealed a non-encapsulated, ill-defined mass with numerous large pigments in the dermis without significant epidermal changes (H&E, ×40). (B) Multiple cavernous angiomatoid areas were surrounded by histiocytes, fibroblasts, pigments, and capillaries. Extravasated red blood cells and multinucleated giant cells were also observed (H&E, ×200).

Fig. 3

The large pigments in tumor mass were positively stained for iron (Prussian blue, ×200).

Fig. 4

(A) Immunohistochemical staining was performed using the avidin-biotin complex method. Most of the tumor cells are strongly positive for vimentin (×200). (B) Endothelial cells lining the cavernous spaces and tumor cells focally stain for CD34. However, the majority of tumor cells are negative for DC34 (×100).