Dermoscopy of desmoplastic melanoma: report of six cases.

Background: Desmoplastic melanoma (DM) is a rare variant of cutaneous melanoma. Its diagnosis is often delayed by an unusual clinical presentation. The dermoscopic features of DM have not yet been described.
Objective: To define the dermoscopic features of DM. Patients and methods A single-institution register-based retrospective study of six cases of histology-proven desmoplastic melanoma for which dermoscopy data were available. The criteria we studied included: network, dots and globules, streaks, regression features, ulceration, number of colours, blue/white veil, and vascular pattern.
Results: Only three cases exhibited one classical feature for a melanocytic lesion; other cases were recognized on the basis of the presence of figures of regression (all six), i.e. white scar-like areas and 'peppering' (three of six), multiple (> 4) colours (five of six), and of melanoma-related vascular patterns (five) such as linear-irregular vessels (four) and milky-red areas (two).
Discussion: We believe that dermoscopy could help in the accurate diagnosis of this rare neoplasm. In the absence of a pigmented network, attention should be given to the identification of features of regression and to melanoma-associated vascular patterns.