Hairy Cell Leukemia with Marked Lymphocytosis

Hairy Cell Leukemia With Marked Lymphocytosis Brian Patrick Adley, MD; Xiaoping Sun, MD, PhD; John M. Shaw, MD; Daina Variakojis, MD airy cell leukemia (HCL) is a rare small B-cell lym- H phoproliferative disorder. The neoplastic cells have round to oval nuclei and abundant cytoplasm with ``hairy'' projections seen in the peripheral blood and bone marrow. They typically diffusely in®ltrate bone marrow and spleen. Immunophenotypically, they strongly express CD103, CD22, CD11c, and CD25. Hairy cell leukemia commonly presents with pancytopenia and splenomegaly with few circulating neoplastic cells. We describe the case of a 42-year-old man who presented at our institution with marked leukocytosis (white blood cell count, 98 300/mL) and splenomegaly. The patient had no signi®cant past medical history. His hemoglobin level was 9.9 g/dL and his platelet count was 154 000/mL. Review of a peripheral blood smear demonstrated marked lymphocytosis consisting of larger than usual lymphocytes with round to oval, eccentrically locat- ed nuclei; small inconspicuous nucleoli; and relatively abundant cytoplasm (Figure 1). Most of the lymphocytes displayed cytoplasmic projections (Figure 1, inset). Many of the cells were tartrate-resistant acid phosphatase (TRAP) positive (Figure 2). A normochromic, normocytic anemia with occasional ovalocytes and teardrop cells was also noted. The bone marrow core biopsy was markedly hypercellular (90%), with most of the medullary space oc- cupied by small to medium-sized, monotonous-appearing lymphocytes with abundant cytoplasm (Figure 3). Flow cytometric analysis performed on the bone marrow aspi- rate demonstrated these cells to be k-light chain restricted and CD191, CD201, CD52, CD102, CD11c1, CD1031,and CD251. The differential diagnosis of the peripheral blood smear in this case would include HCL; chronic lymphocytic leukemia; prolymphocytic leukemia; the leukemic phase of mantle cell, follicular, and marginal zone lymphomas; and the rare Japanese variant of HCL (HCLV). The morphology, cytochemistry, and immunophenotype (CD191, CD201, CD11c1, and CD1031) of the neoplastic cells in our case are diagnostic for classic HCL, although the high lymphocyte count is a very unusual ®nding. The HCL variant, although extremely uncommon, does typically present with a marked lymphocytosis (usually around 50 000/mL). However, the neoplastic cells in HCLV typically have prominent nucleoli (resembling prolympho- Accepted for publication September 11, 2002. From Northwestern University, Chicago, Ill (Drs Adley, Sun, and Varia- kojis); and Northwestern Memorial Hospital, Chicago, Ill (Dr Shaw). Reprints: Brian P. Adley, MD, 251 E Huron, Feinberg Bldg 7-325, Chicago, IL 60611 (e-mail: [email protected]). Arch Pathol Lab MedÐVol 127, February 2003 Hairy Cell LeukemiaÐAdley et al 253 cytes) and are CD252 and CD1032. This was not the case antibody) by ¯ow cytometry. Because positive TRAP in our patient. staining is occasionally seen in other conditions, the ques- Cases of HCL with profound lymphocytosis have been tion is raised as to whether some of the cases reported reported only rarely in the literature. The highest white were truly cases of classic HCL. Moreover, this case as blood cell count reported was greater than 500 000/mLin well as possibly the previous cases illustrate that although a 49-year-old man who was treated with leukophoresis to patients with classic HCL usually present with pancyto- bring his count to 20 000/mL.1 Although the case was re- penia, rare cases can present with marked leukocytosis. portedly TRAP positive, immunophenotyping was not This possibility should be kept in mind in order to provide performed. A 71-year-old man with classic HCL (CD221, accurate diagnosis and proper treatment of this disease. CD251 by immunohistochemistry) reportedly had a white Our patient received a cycle of 2-chlorodeoxyadenosine (2- blood cell count as high as 323 000/mL. He eventually died CdA) immediately following diagnosis. Three months lat- er, circulating hairy cells were not seen on peripheral as a result of leukostasis in the cerebral vasculature, which 2 3 blood smear. Platelet and white blood cell counts normal- caused massive intracerebral hemorrhage. Golomb et al ized. A bone marrow biopsy performed at this time reviewed 71 cases of HCL and found that only 3 (4%) had showed minimal residual disease (approximately 5% 3 white blood cell counts greater than 25 3 10 /mL. Other hairy cells), and ¯ow cytometry detected a small CD11c1, authors have reported similar results; however, in most CD251, CD1031 population of hairy cells. Currently, the cases immunophenotyping was not performed. patient is doing well clinically. Our case represents another unusual case of HCL, with References the diagnosis con®rmed by morphology, immunopheno- 1. Worsley A, Cuttner J, Gordon R, Reilly M, Ambinder EP, Conjalka M. Ther- typing, and cytochemistry. Additionally, although the oth- apeutic leukapheresis in a patient with hairy cell leukemia presenting with a white cell count greater than 500,000/microliter. Transfusion. 1982;22:308±310. er cases cited were reportedly TRAP positive, our case 2. Ng MH, Tsang SS, Ng HK, Sriskandavarman V, Feng CS. An unusual case may be the ®rst reported in the literature with such a of hairy cell leukemia: death due to leukostasis and intracerebral hemorrhage. Hum Pathol. 1991;22:1298±1302. marked lymphocytosis (95 000/mL) that was shown to be 3. Golomb HM, Catovsky D, Golde DW. Hairy cell leukemia: a clinical review CD11c1 and CD1031 (a relatively new and more speci®c based on 71 cases. Ann Internal Med. 1978;89:677±683. 254 Arch Pathol Lab MedÐVol 127, February 2003 Hairy Cell LeukemiaÐAdley et al.

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