Resolution of refractory pruritus with aprepitant in a patient with microcystic adnexal carcinoma

Substance P is an important neurotransmitter implicated in itch pathways.1 After binding to its receptor, neurokinin-1 (NK-1), substance P induces release of factors including histamine, which may cause pruritus.2 Recent literature has reported successful use of aprepitant, an NK-1 antagonist that has been approved by the US Food and Drug Administration for the treatment of chemotherapy-induced nausea and vomiting, for treatment of pruritus. We report here the case of a patient with microcystic adnexal carcinoma (MAC) who presented with refractory pruritus and who had rapid and complete resolution of itch after administration of aprepitant.