Clinical and dermoscopic characteristics of desmoplastic melanomas

To describe and analyze the clinical and dermoscopic characteristics of desmoplastic melanoma (DM) as a function of pathologic subtype and phenotypic traits.

Retrospective case series.

Eight high-risk dermatology clinics.

Patients with DM confirmed by histopathologic analysis whose records included a high-quality dermoscopic image.

Clinical, dermoscopic, and histopathologic features of DM.

A total of 37 DM cases were identified. The majority of patients had fair skin, few nevi, and no history of melanoma. Lentigo maligna was the most frequent subtype of melanoma associated with DM. The most frequent clinical presentation of DM was a palpable and/or indurated lesion located on sun-exposed skin. Forty-three percent of cases were classified as pure DM, and 57% as mixed DM. Pure DM lesions were thicker than mixed DM lesions (4.10 vs 2.83 mm) (P = .22) and were less likely to have an associated epidermal non-DM component (63% vs 100%) (P = .004). Dermoscopically, DMs had at least 1 melanoma-specific structure, the most frequent being atypical vascular structures. Peppering was more frequently seen in pure DM (44% in pure DM vs 24% in mixed DM) (P = .29). In contrast, crystalline structures, polymorphous vessels, and vascular blush were more commonly seen in mixed DM.

Though DM can be difficult to diagnose based on clinical morphologic characteristics alone, dermoscopy has proved to be a useful aid during the evaluation of clinically equivocal lesions or those lesions with a benign appearance. The most common dermoscopic clues observed in DMs included atypical vascular structures, peppering, and occasionally other melanoma-specific structures.