A case of a 44 years old patient with inoperable gastric adenocarcinoma and exuberant lesions of Acanthosis Nigricans is described. He died nine months after the diagnosis, having experienced disappearance of the cutaneous manifestations after the cytostatic treatment done. The literature about Acanthosis Nigricans is reviewed and the importance of precocious search of associated malign disease is stressed. It was demonstrated by immunocytochemistry, positivity to NSE (neuron specific enolase) and ACTH, in the patient gastric tumour cells which allows them to be classified as neuroendocrine cells. It is suggested that Acanthosis Nigricans is a manifestation of a para-endocrine syndrome.