Subcutaneous dermatofibroma showing a depressed surface

Subcutaneous dermatofibroma: a rare case report with review of literature

A purely Sub-cutaneous benign fibrous histiocytoma (BFH; dermatofibroma) is rarely reported, as it is usually a dermally located mesenchymal tumour and in absence of supportive immunohistochemical (IHC) studies, it is often misdiagnosed. We are describing a case of a 19-year-old female who presented to the skin outpatient department with a painful swelling on the medial side of her thigh. Fine needle aspiration (FNA) revealed a sub-cutaneous spindle cell (mesenchymal) lesion which was corroborated on histopathology, with differentials of BFH and dermatofibrosarcoma protruberans (DFSP). BFH constitutes a diagnostic dilemma for both clinicians and pathologists, because the lesions share common clinical symptoms, radiological characteristics and histological features with many varied entities. For its subtyping and confirmation; immunohistochemical (IHC) studies were undertaken. In the present case, positivity of IHC markers, vimentin and smooth muscle actin emphatically proved that BFH arose exclusively from the subcutaneous region, with no dermal origin. Also, a negative CD34 immunostaining, along with low B-cell lymphoma 2 (Bcl-2) expression ruled out DFSP (both are strongly expressed in DFSP), MFH and other malignant mesenchymal lesions. Negative CD 68 staining ruled out giant cell lesions and their congeners. This case is worth reporting, as it not only describes a rare case presentation of BFH, but as it also highlights the importance of IHC, thus helping to comprehensively clinch the diagnosis by systematically ruling out other differentials.

Subcutaneous dermatofibroma

Dermatofibroma (DF) is usually confined to the dermis and the overlying epidermis is usually hyperplastic. Although DF with deep subcutaneous extension is commonly encountered, purely subcutaneous DF is uncommon. In this review, we describe a case of a 41-year-old male patient who presented with a painless, subcutaneous, hard papule on the left thigh. After the skin had been incised the lesion was totally removed, and histopathology revealed a subcutaneous dermatofibroma.

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

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.