Blasts with folded nuclei: A histopathologic finding in myeloid leukemia cutis with NPM1 and FLT3 mutations

Abstract Leukemia cutis is a term used to describe cutaneous manifestations of leukemic infiltration of the skin and portends a poor prognosis. Cutaneous involvement by hematopoietic/lymphoid tumors can occur before, concurrently, or after the initial diagnosis. Early involvement of dermatologists and timely biopsies play a crucial role in achieving a prompt diagnosis. Prior reports of acute myeloid leukemia have revealed a strong association between the cup‐like nuclear morphology observed in bone marrow specimens and concurrent mutations of NPM1 and FLT3‐ITD . In cutaneous tissue sections of leukemia cutis, folded or indented nuclei may represent the “cup‐like” counterpart previously described in bone marrow specimens. Recognizing this morphological feature could aid in identifying this molecular subtype of leukemia cutis. In this study, we present a case of leukemia cutis in a 63‐year‐old female with AML and NPM1 and FLT3‐ITD mutations, demonstrating scattered indented/folded nuclei.