Disappearing Atypical Lentiginous Pigmentation of the Desmoplastic Malignant Melanoma

A 38-year-old man presented with a black pigmented patch overlying his upper lip, a part of the gingiva and the hard palate. An intradermal tumor mass was palpated at the central portion of the pigmented patch of the upper lip.

Diphenylcyclopropenone (DPCP) is a potent contact sensitizer that could stimulate non-specific immunity. We report a case of desmoplastic malignant melanoma (DMM) in which an atypical lentiginous pigmentation disappeared with topical DPCP immunotherapy and the dermal tumor mass was removed by a surgical wedge-shaped excision. Though an atypical lentiginous pigmentation of DMM sometimes undergoes extensive spontaneous regression, in our case it could be attributed to the therapeutic effect of topical DPCP immunotherapy rather than a spontaneous regression.