Acanthosis Nigricans Manifesting as a Paraneoplastic Syndrome Associated With Cholangiocarcinoma

We present the case of a 64-year-old woman with type 2 diabetes who was diagnosed with early-stage intrahepatic cholangiocarcinoma and underwent partial hepatectomy followed by adjuvant chemotherapy. The patient simultaneously developed skin lesions compatible with acanthosis nigricans (AN). Thirty-seven months after completing chemotherapy, the patient had a recurrence of extensive skin and mucosal lesions compatible with AN. A thoracic-abdominal-pelvic (TAP) CT showed a relapse with hepatic hilar adenopathy. Currently, she is under evaluation to undergo radical treatment. Malignancy is a rare cause of AN and skin lesions can arise before, during, or after the diagnosis. As a paraneoplastic syndrome, it is usually related to gastric adenocarcinoma, with cholangiocarcinoma being a rare entity in this setting. Although an uncommon manifestation, the malignant etiology should be considered among other prevalent causes, such as metabolic disorders, and establishing an association can lead to an early diagnosis and initiation of curative treatment.