Variants of dermatofibroma--a histopathological study

Abstract

Several variants of dermatofibroma have been described. They are essentially distinguished by their clinical and histopathological features. To review the mainfeaturesof these variants, a retrospective study of skin biopsies and tissue excisions of dermatofibromasperformed in the dermatology and venereology service at the Hospital Garcia de Orta between May 2007 and April 2012 was carried out. During that period, 192 dermatofibromas were diagnosed in 181 patients, the lesions being more common in women. Median age of the study population was 48 years. The most common lesion site was the limbs (74% of patients). The histopathological types found were common fibrous histiocytoma (80%) and the aneurysmal (5.7%),hemosiderotic (5.7%), epithelioid (2.6%), cellular (2.1%), lipidized (2.1%), atrophic (1.0) and clear cell (0.5%) variants. Based on these findings, this review focuses on the clinical and histological features of the various variants of dermatofibroma in terms of their clinical presentation, distinct histopathological features, differential diagnosis and prognosis.

GRAPH 1

Age and gender distribution

GRAPH 2

Distribution of the lesions

FIGURE 1

Common fibrous histiocytoma: A - An ill-defined noncapsulated dermal lesion composed of interlacing fascicles of spindled cells, in this case separated from the epidermis by a grenz zone (H&E x 40); B - Globular collagen bundles at the periphery of the lesion (H&E 100x); C - Associated epidermal changes: hyperkeratosis, acanthosis and basal cell layer hyperpigmentation (H&E 40x)

FIGURE 2

A - Aneurismal fibrous histiocytoma: a hemorrhagic space without endothelial lining (H&E 40x); B - Hemosiderotic fibrous histiocytoma: hemosiderin deposition due to hemorrhage (H&E 100x)

FIGURE 3

Epithelioid fibrous histiocytoma: rounded epithelioid cells with abundant eosinophilic cytoplasm (H&E 100x)

FIGURE 4

Lipidized fibrous histiocytoma: foamy cells surrounded by collagen bundles (H&E 100x)

FIGURE 5

A - Clear cell fibrous histiocytoma: a lesion composed of clear cells occupying the reticular dermis (H&E 40x); B. clear cells with vesicular nuclei in the reticular dermis (H&E 100x)