Psammomatous malignant melanoma arising in an intradermal naevus

Aims: A wide variety of differentiation patterns may be found in malignant melanoma. Schwannian features are unusual. and mostly present in the desmop lastic variant. We report the first description of psammoma bodies in malig nant melanoma. Methods and results: A malignant melanoma arose in an intradermal naevus of the scalp in a 51-year-old woman, displaying focal neural-like features in the form of rosette-like pseudo-meissnerian alveolar nests, as well as num erous psammoma bodies grouped in a few areas. Tumour cell immunostaining fo r S100. HMB45, NKI-C3, and vimentin was detected. In addition, both maligna nt and benign melanocytic cells showed widespread MART-1 immunoreactivity. Differential diagnosis with psammomatous melanotic schwannoma, a feature of Carney's complex, is particularly emphasized, since dermal variants of thi s nerve sheath neoplasm have been described. In addition, its potential rel ationship with cutaneous malignant melanotic neurocristic tumour is discuss ed. Conclusions: This is. to our knowledge, the first reported case of cutaneou s malignant melanoma with psammoma bodies.