MITF and neoplasm: α-MSH induces skin pigmentation,18 binds to extracellular receptors, and induces MITF expression, a key transcription factor for melanocyte differentiation and survival.19 It is possible that a mutation in the original ACTH-producing tumor lead to increased cleavage of POMC or ACTH into α-MSH, which in turn stimulated the expression of MITF, leading to melanocytic phenotype transformation.