Malignant acanthosis nigricans associated with prostate cancer: a case report

BACKGROUND Acanthosis nigricans is characterized by hyperpigmentation and hyperkeratosis of the skin or mucous membranes. Its malignant form is associated with internal neoplasms, especially gastric adenocarcinoma (55-61%). Coexistence with prostate cancer is uncommon. In the paraneoplastic type of this dermatosis, the skin and mucous lesions are characteristically of more sudden onset and more severe than those in the benign form. The efficacy of various treatment strategies remains disappointing. CASE PRESENTATION We here report a case of 66-year-old Caucasian patient with metastatic prostate cancer and a mild form of acanthosis nigricans that preceded the diagnosis of malignancy and resolved with chemotherapy in parallel with the prostate cancer. The dermatosis recurred when the prostate cancer progressed. CONCLUSION Concurrent acanthosis nigricans and prostate cancer is rare, and few such cases have been reported. Anti-tumor therapy occasionally results in regression of this dermatosis. Underlying malignant disease should be suspected in individuals with elderly-onset of acanthosis nigricans.