A clinical and histopathological study of 122 cases of dermatofibroma (benign fibrous histiocytoma)

Abstract

Background: Many variants of dermatofibromas have been described, and being aware of the variants of dermatofibromas is important to avoid misdiagnosis.

Objective: We wanted to evaluate the clinical and pathologic characteristics of 122 cases of dermatofibromas.

Methods: We retrospectively reviewed the medical records and 122 biopsy specimens of 92 patients who were diagnosed with dermatofibroma in the Department of Dermatology at Eulji Hospital of Eulji University between January 2000 and March 2010.

Results: Nearly 80% of the cases occurred between the ages of 20 and 49 years, with an overall predominance of females. Over 70% of the lesions were found on the extremities. The most common histologic variant was a fibrocollagenous dermatofibroma (40.1%). Other variants included histiocytic (13.1%), cellular (11.5%), aneurysmal (7.4%), angiomatous (6.5%), sclerotic (6.5%), monster (4.9%), palisading (1.6%) and keloidal dermatofibromas (0.8%). There were 9 dermatofibromas (7.3%) that were the mixed type with two co-dominant histologic features.

Conclusion: The results of this study are consistent with previous reports on the clinical features of dermatofibromas. However, we observed several characteristic subtypes of dermatofibroma and we compared the frequency of the histologic subtypes.

Keywords: Dermatofibroma.

Fig. 1

The age and gender distribution of the patients.

Fig. 2

The size of the lesions.

Fig. 3

The number of lesions per each patient.

Fig. 4

Configuration of the lesions.

Fig. 5

Distribution of the lesions (%).

Fig. 6

Classification into the variants of dermatofibroma. The most common histologic variant was a fibrocollagenous dermatofibroma (n=49, 40.1%), followed by histiocytic (n=16, 13.1%), cellular (n=14, 11.5%), aneurysmal (n=9, 7.4%), angiomatous (n=8, 6.5%), sclerotic (n=8, 6.5%), monster (n=6, 4.9%), palisading (n=2, 1.6%) and keloidal dermatofibroma (n=1, 0.8%).

Fig. 7

Various histologic types of dermatofibroma. (A) The fibrocollagenous type shows a predominance of collagen and fibroblasts in a whorled arrangement (H&E, ×100). (B) The histiocytic type shows sheets of histiocytes with many melanophages (H&E, ×100). (C) Foamy histiocytes in the histiocytic type (H&E, ×40). (D) The cellular type showing high cellularity with short fascicular and storiform growth (H&E, ×100). (E) The aneurysmal type is characterized by blood-filled spaces reminiscent of cavernous hemangioma (H&E, ×40). (F) The sclerotic type with marked hyalinized eosinophilic collagen bundles (H&E, ×100). (G) The angiomatous type with numerous small branching vessels in a collagenous stroma (H&E, ×100). (H) The monster type with multinucleate giant cells with large, hyperchromatic, bizarre nuclei (H&E, ×100). (I) The palisading type with verocay-like body in the center of the lesion (H&E, ×100). (J) The keloidal type with broad, thick and irregularly oriented collagen bundles (H&E, ×100).

Fig. 8

Histopathologic features of dermatofibroma. (A) Typical epidermal change of dermatofibroma-induced hyperkeratosis, acanthosis and basal layer hyperpigmentation (H&E, ×100). (B) Lymphoid nodule formation in the cellular type (H&E, ×40). (C) Mucin deposition in the cellular type (alcian blue, ×40).