<prompt> Acanthosis nigricans is seen in?GI malignancyLung cancerBreast cancerAll above  <response>: ANSWER: D All aboveREF: Harrisons 18th ed chapter 53Acanthosis nigricans can also be a reflection of an internal malignancy, most commonly of the adenocarcinoma of the gastrointestinal tract, lung, uterus and breastIt appears as velvety hyperpigmentation, primarily in flexural areas. However, in the majority of patients, acanthosis nigricans is associated with obesity and insulin resistance, but it may be a reflection of an endocrinopathy such as acromegaly, Cushings syndrome, polycystic ovary syndrome, or insulin-resistant diabetes mellitus type A, type B, and lipoatrophic forms. 