Introduction: Hairy cell leukemia-variant (HCL-V) is an uncommon disorder, accounting for approximately 0.4% of chronic lymphoid malignancies and 10% of all HCL cases, without sexual predominance. Here is an attempt to submit a rare case presentation of HCL-V.

Case:A 66 year old female presented to the clinic after she was referred from her primary care for further evaluation of pancytopenia. Past medical history was significant for diabetes mellitus and hypertension. Splenomegaly was noted on examination. Initial bloodwork showed a leukocyte count of 4.9, hemoglobin level of 11.8, platelet count of 78. LDH was 166. CT scan showed significant splenomegaly along with retroperitoneal adenopathy. Peripheral blood flow cytometry demonstrated a CD11c positive monoclonal B cell population suggestive of Hairy Cell Leukemia variant, positive for CD19, CD20, CD22, CD45, CD52, and kappa (moderate-bright), negative for CD5, CD10, CD23, CD38, CD103, CD123, BRAF V600. Left shift myeloid elements were noted but no significant myeloid blasts were noticed. She was diagnosed HCL-V with 17p deletion and 90% marrow involvement. She was treated with 8 doses Rituximab. After 1 year, she relapsed and was started on Cladribine and Rituximab weekly for 8 doses. She relapsed 1 year after Cladribine and Rituximab with splenomegaly and cytopenias, and she was started on Ibrutinib. 4 months after treatment with Ibrutinib, her cytopenias improved with normalization of spleen size. She is tolerating off label medication Ibrutinib well and currently asymptomatic.

Discussion: This case represents an extremely rare hematological malignancy a distinct case of HCL-v due to 17p deletion and refractory to multiple therapies. Patients with multiply relapsed HCL-v are also appropriate candidates for moxetumomab pasudotox because HCL-v retains a high level of expression of CD22. Hairy cell leukemia variant is a chronic lymphoproliferative disorder whose characteristics resemble the classic form and splenic marginal zone lymphoma, making differential diagnosis essential for therapeutic follow-up, as hairy cell leukemia variant has a decreased response to drugs prescribed for the classic form. Immunophenotyping is a key tool for diagnosis, as some markers are different between these neoplasms. Therefore, immunophenotyping, clinical, morphological, and immunohistochemical manifestations must be considered in the differential diagnosis.


No relevant conflicts of interest to declare.

Author notes


Asterisk with author names denotes non-ASH members.

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