[Trigeminal neuralgia presenting as a deep recurrent desmoplastic neurotropic melanoma of a lentigo maligna].

INTRODUCTION

Neurotropic melanoma is a particular anatomopathological form corresponding to dermal proliferation of desmoplastic cells of neuroid differentiation. We report a new case of neurotropic melanoma revealed by facial neuralgia.

CASE REPORT: A 64 year-old man presented in 1996 with a lentigo maligna on the right cheek treated by complete excision. After 2 years of medical supervision, a pigmented lesion recurred leading to new surgical treatment. The histological examination of the total lesion showed intra-epidermal atypical melanocyte proliferation without dermal invasion. In 1999, right trigeminal neuralgia occurred without associated cutaneous change. Cranial MRI revealed an infiltration of the right trigeminal nerve. Endo-buccal surgery disclosed a black swelling of the trigeminal nerve. Histological examination and immunohistochemistry revealed a desmoplastic melanoma.

DISCUSSION: Neurotropic melanoma with nerve invasion by malignant cells presenting as a trigeminal neuralgia is rare. Our case report underlined the depth of the neurotropic melanoma and the initial existence of a lentigo maligna without associated "neurotropic" melanoma.