Hemosiderotic Dermatofibroma: A Rare and Atypical Variant Capable of Clinically Resembling Melanoma

Abstract

A dermatofibroma (DF) is a common, benign tumor composed of fibroblastic and histiocytic cells. DF presents clinically with several different reported variants. One rare variant is hemosiderotic DF (HDF), which is made up of small blood vessels and hemosiderin deposits. HDF can be indistinguishable, clinically, from melanoma, making the use of other pathological tools crucial in the diagnosis. We report the case of a 25-year-old male medical student from the Caribbean who presented to our clinic with a single asymptomatic pigmented cystic lesion on his left posterior calf. The cystic lesion was excised surgically. Histopathology examination of the excised mass revealed a moderately cellular, poorly demarcated, dermal, fibrohistiocytic proliferation. Pathology consultation confirmed a diagnosis of HDF.

Hemosiderotic dermatofibroma mimicking melanoma: A case report and review of the literature

“…1 It is reportedly associated with melanoma-like pattern or vascular tumor-like pattern on dermatoscopy. 10,13 In this case, the black-colored lesion with asymmetric border combined with peripheral blackish hue in an 85-year-old woman poses a diagnostic challenge for the dermatologist. Because wide local excision with negative margins is performed for melanoma, a definitive diagnosis of DF is crucial to avoid unnecessary surgical treatment.…”

“…HDF is considered to be a rare variant of DF, constituting 5.7% of all DF cases 1 . It is reportedly associated with melanoma‐like pattern or vascular tumor‐like pattern on dermatoscopy 10,13 . In this case, the black‐colored lesion with asymmetric border combined with peripheral blackish hue in an 85‐year‐old woman poses a diagnostic challenge for the dermatologist.…”

“…Majority of these cases raise concern for melanoma following initial dermatoscopic examination and excision was performed for a definite diagnosis. 11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] The area rich in poorly formed vessel-like structures can make the lesion look like a vascular tumor such as Kaposi's sarcoma both microscopically and clinically. 28 Given the patient having no clinical history of immunosuppressive diseases/conditions, the chance of Kaposi's sarcoma is likely to be very low.…”

“…In this scenario, a definite diagnosis could only be made by histopathological examination. There are three cases of HDF reported in the literature from the United States 13‐15 . Here, we report another case of HDF which was clinically suspicious for melanoma.…”

Dermoscopic findings of hemosiderotic dermatofibroma: A comprehensive review

“…The diagnosis of this variety is hardly clinical. Because hemosiderotic DF's dermatoscopy has atypical patterns that make them indistinguishable from malignant melanocytic lesions (melanoma as the main differential diagnosis), literature reports diagnosis of this entity achieved by biopsy [10,12,[14][15][16][17][18] (Table 1). Cases with dermatoscopic description and histological confirmation were obtained from these studies, eliminating duplicate data in literature [1,16] (Table 2).…”