Paraneoplastic Acanthosis Nigricans: The importance of exhaustive and repeated malignancy screening.

Paraneoplastic acanthosis nigricans (P-AN) characteristically has a sudden onset, rapid progression, and extensive cutaneous involvement. The association between P-AN and internal malignancy is well established and the most common association is with adenocarcinoma of gastrointestinal origin. We present the case of an 81-year-old man with a 12-month history of anorexia, weight loss, and clinical evidence of extensive acanthosis nigricans. After exhaustive and repeated investigations a papillary thyroid carcinoma and a follicular adenoma were identified and he improved upon its resection. To our knowledge, P-AN in association with thyroid neoplasm has been reported on only one previous occasion.