급성백혈병의 형태와 유사한 모세포양 이차성 형질세포백혈병의 국내 첫 증례 보고

Abstract

Blastoid plasma cell leukemia (PCL) is an exceptionally rare disease, with only a few documented cases worldwide. This condition is characterized by plasma cells exhibiting blastoid morphology, indistinguishable from leukemic blasts. Here, we present the first reported case of blastoid PCL in Korea. A 74-year-old male patient with refractory plasma cell myeloma exhibited 40% immature cells on peripheral blood smear. Bone marrow aspirate revealed 84.3% immature cells, demonstrating kappa-restriction by in situ hybridization on bone marrow biopsy. Flow cytometry showed negative-to-dim expression of CD45 and dim expression of CD138 and CD38. Complex karyotyping revealed a series of abnormalities, with nextgeneration sequencing revealing whole gene deletion of TP53, RB1, TRAF3, DIS3, NFKBIA, and KMT2C, alongside a TP53 mutation (NM_000546.6: c.376-1G>C) with a variant allele frequency (VAF) of 93%. This case highlights the necessity for comprehensive diagnostic evaluation, as blastoid PCL may be morphologically misidentified as other forms of acute leukemia.