Abstract
In typical acute promyelocytic leukemia (APL), the fusion gene PML::RARA is formed by a chromosomal translocation of t(15;17)(q24.1:q21.2). However, in rare cases, cryptic t(15;17)(q24.1:q21.2) exists when a fine region of RARA is inserted into PML, forming the fusion gene PML::RARA, but no t(15;17)(q24.1:q21.2) is detected. We report a case of therapy-related cryptic APL diagnosed on the basis of a bone marrow specimen obtained during treatment for follicular lymphoma. The patient was a female in her 60s. During the treatment of follicular lymphoma, leukopenia was observed and bone marrow puncture was performed. Bone marrow examination did not reveal any histopathological or chromosomal abnormalities. On the basis of a small number of faggot cells in the bone marrow image, the hematology technologist suspected APL and reported this to the physician in charge, who asked for additional genetic tests, which revealed the fusion gene PML::RARA. When checking bone marrow images, it is important that hematology technologists keep therapy-related myeloid neoplasms in mind and do not miss even a few abnormal cells when checking bone marrow images for an early diagnosis and treatment. I reaffirmed this importance in this study.
