Hairy Cell Leukemia With Splenic Rupture: Hematological Changes and Disappearance of Hairy Morphology After Splenectomy

We present the case of a 64-year-old man who suffered a splenic rupture following a fall. A peripheral blood smear showed mononuclear cells with "hairy" cytoplasmic projections. A computed tomography (CT) angiogram revealed splenomegaly with a hematoma and active contrast extravasation. He underwent coil embolization of the splenic artery but subsequently developed worsening abdominal pain and ileus, requiring a splenectomy. Pathological examination of the spleen showed extensive infiltration by hairy cell leukemia (HCL). Bone marrow biopsy revealed hypercellular marrow predominantly infiltrated by HCL cells positive for CD20, CD103, and the BRAF V600E mutation. After the splenectomy, pancytopenia gradually improved. The symptoms of the patient, such as fatigue, weight loss, and night sweats, were also resolved. Circulating HCL cells were significantly reduced, and the "hairy" morphology became smoother. To our knowledge, this morphologic change of the hairy cells after splenectomy has not been reported in the past. Its mechanism is not known. We postulate that splenectomy may induce molecular or immunological changes that alter HCL cell behavior, which warrants further research.