Probable Rabson-Mendenhall syndrome presenting with acanthosis nigricans: a case report

Rabson-Mendenhall syndrome (RMS) is a rare autosomal recessive disorder caused by mutations in the insulin receptor gene (INSR), resulting in severe insulin resistance. We report the case of an 8-year-old boy who presented with progressive acanthosis nigricans of the neck, coarse facial features, generalized hypertrichosis, dental abnormalities, a fissured tongue, thickened nails, penile hypertrophy, and hepatomegaly. Laboratory results indicated hyperinsulinemia, severe insulin resistance and fasting hypoglycemia. Based on the clinical and laboratory findings, Rabson-Mendenhall syndrome was considered. Genetic confirmation was not performed because it was unavailable in our country. This case highlights the importance of recognizing acanthosis nigricans as a clinical marker of inherited metabolic syndromes, and the important role of dermatologists in its early recognition.