#00065973

A 82 year old male with a history of atypical CLL and status post of chemotherapy for pancreatic carcinoma five years ago presented prominent abnormal lymphocytosis with normal hemoglobin level and platelet count. The atypical lymphoid cells are mostly intermediate size with increased prolymphocytoid cells (panel A, Wright stain, 100x objective). Auer-rod like inclusions were easily identified in cytoplasm, they were negative for Cytochemical myeloperoxidase (MPO) staining (panel B, cytochemical MPO staining with Giemsa-Wright counter stain, 100x objective). Flow cytometry study showed a B-cell population with surface kappa light chain restriction, and CD34+ myeloblasts were not increased (panels C-D). Cytogenetic analysis showed 45,XY,t(5;14)(q33;q32), der(8;17)(q10;q10),del(16)(q22)[7]/ 44~45,idem,-13,-14,+1~3mar[7]/46,XY[6]. CLL FISH panel study revealed loss of one copy of each of TP53and D13S319, and Trisomy 12. NGS mutation assay detected CCND3 c.851del, NXF1 c.454A>T, and TP53 c.363_375+12del. Patient is currently following up at outpatient clinic.

Auer rods-like inclusions can be seen in low-grade B-cell lymphomas and plasma cell neoplasms. It's important to be aware of this morphology variation, especially when the neoplastic cells with prolymphocytoid or blastoid morphology. Performing cytochemical MPO stain and flow cytometry study will be helpful for establishing definitive diagnosis.