Thrombocytosis

We report a novel case of T-prolymphocytic leukemia, small cell variant, associated with complex cytogenetic findings including t(3;22)(q21;11.2) and elevated serum β^sub 2^-microglobulin. The diagnosis is based on morphologic, immunophenotypic, cytogenetic, and molecular analysis of peripheral blood and bone marrow. In contrast to most reported cases of T-prolymphocytic leukemia, this patient did not present with lymphadenopathy or organomegaly. Moreover, only a moderate leukocytosis (25.3 × 10^sup 3^/µL) was evident at presentation. In the absence of any specific treatment, the patient is doing well, with a stable white blood cell count 12 months following presentation. Further investigation may be warranted to determine whether the unusual cytogenetic findings and elevated serum β^sub 2^-microglobulin are associated with the indolent clinical course in this patient.

(Arch Pathol Lab Med. 2005;129:1164-1167)

T-cell prolymphocytic leukemia (T-PLL) is a rare aggressive condition that constitutes approximately 2% of cases of small lymphocytic leukemia in adults. Most patients present with hepatosplenomegaly, lymphadenopathy, and a high leukocyte count. T-cell prolymphocytic leukemia is characterized by proliferation of small to medium-sized prolymphocytes with nongranular basophilic cytoplasm; round, oval, or markedly irregular nuclei; and a visible nucleolus. Twenty percent of cases of T-PLL belong to the small cell variant of T-PLL. T prolymphocytes show a mature postthymic phenotype with expression of CD2, CDS, and CD7, and the T-cell receptor β and γ genes are clonally rearranged. The most frequent chromosomal abnormalities in T-PLL include inversion of chromosome 14 with breakpoints in the long arm of qll and q32 and abnormalities of chromosome 8.1-4

We present a case of an 87-year-old man diagnosed with T-PLL based on morphology, immunophenotype by flow cytometry, and cytogenetic and molecular T-cell receptor studies of blood and bone marrow. In addition to the well-known chromosome 14, 11, 8, and 2 abnormalities noted in T-PLL, a t(3;22)(q21;11.2),-18 and +mar[7] were also present in this patient. To our knowledge, such cytogenetic findings have not been reported in other cases of T-PLL. Instead, t(3;22)(q21;11.2) has been reported in a case of myelodysplastic syndrome-derived leukemia with thrombocytosis.5 Moreover, our patient also had an elevated serum β^sub 2^-microglobulin level, which is usually found in B-cell lymphoproliferative disorders and multiple myeloma.6,7 The patient is clinically well and has a stable white blood cell count 12 months following presentation, in the absence of any specific therapy.

We report this interesting case of T-PLL and discuss the unique findings of the absence of organomegaly and lymphadenopathy, t(3;22)(q21;qll.2),-18,+mar[7], and elevated serum p2-microglobulin with reference to other cases described in the literature. Further investigation may be warranted to determine whether these unusual findings may be associated with a more indolent clinical course.

REPORT OF A CASE

An 87-year-old man visited his physician complaining of back pain of 2 weeks' duration. He also described general weakness and 5.4-kg weight loss during a period of 2 months. His past medical history was significant for a resected colonie adenocarcinoma 10 years earlier. Physical examination was unremarkable. A complete blood count showed anemia with a hemoglobin level of 11.2 g/dL (reference range, 14.0-18.0 g/dL) and a hematocrit of 34.0% (reference range, 42.0%-52.0%), leukocytosis with a white blood cell count of 25.3 × 10^sup 3^/µL (reference range, 4.8-10.8 × 10^sup 3^/µL and lymphocytosis (64% lymphocytes; reference range, 20.0%-40.0%). The platelet count was normal (209 × 10^sup 3^/ µL; reference range, 150-400 × 10^sup 3^/µL). Evaluation of the peripheral blood smear showed an increase in small lymphocytes with coarse chromatin, a small amount of cytoplasm, and no nucleoli. Serum β^sub 2^-microglobulin was markedly elevated (5.4 µg/ mL; reference range, 0.6-2.0 µg/mL). The remainder of the serum chemical profile was normal. A spiral computerized tomographic scan of the abdomen and pelvis showed bilateral renal cysts and prostate enlargement. No organomegaly or lymphadenopathy was noted. Bone marrow aspiration and biopsy disclosed the presence of T-PLL, small cell variant, based on World Health Organization criteria.1

The patient was treated with biweekly doses of recombinant erythropoietin (40000 U every 2 weeks). His general condition improved, and the back pain disappeared. Follow-up laboratory studies showed an improving hematocrit and a stable white blood cell count. Because the patient became asymptomatic, and in consideration of his old age, no further therapy was considered. The patient is seen once a month and is doing well 12 months after the initial diagnosis of T-PLL.

PATHOLOGIC FINDINGS

Morphologie Analysis

The Wright-stained peripheral blood smear revealed leukocytosis (25.3 × 10^sup 3^/µL; reference range, 4.8-10.8 × 10^sup 3^/µL) and lymphocytosis (64%; reference range, 20%-40%). The lymphocytes, small in size, had coarse nuclear , chromatin; slightly irregular nuclear membrane; and scant, nongranular basophilic cytoplasm. No nucleoli were noted (Figure 1). The bone marrow smears showed vari- able cellularity. The Wright-stained bone marrow aspirate smears were significant for an increase in small lymphocytes, ranging from 20% to 40% of all nucleated cells. The lymphocytes were similar in morphology to those in the peripheral blood. The hematoxylin-eosin-stained bone marrow biopsy was small and had a low cellularity (5%-10%) with occasional small lymphocytes. Because of inadequate core biopsy sampling, it was thought that the bone marrow aspirate was more representative of the patient's hematologic status.

Immunophenotypic Analysis

Flow cytometric analysis was performed on an EPIC XL-MCL flow cytometer (Beckman Coulter, Miami, Fla) using monoclonal antibodies CD2, CD3, CD4, CD5, CD8, CD10, CD16, CD19, CD20, CD23, CD56, CD57, FMC7 (Beckman Coulter); CD43 (Serotec, Raleigh, NC); and κ and λ (DakoCorporation, Carpinteria, Calif). Flow cytometric studies of bone marrow showed a marked expansion of T cells (95% of the total lymphocyte gate), which were positive for CD3, CD4, CD5, and CD43.

Molecular Analysis

DNA was extracted from peripheral blood using a standard phenol/chloroform technique. Following digestion with BamHI, BglII, and EcoRI (all from Amersham Pharmacia Biotech, Piscataway, NJ), the DNA was examined for rearrangement of the T-cell receptor β chain gene using probes to the first and second joining regions (Tbjlj2, manufactured by Jeff Sklar8). Evidence of a rearranged T-cell receptor β chain gene indicative of a monoclonal T-cell lymphocyte population was detected in the restriction digests by Southern hybridization analysis (Figure 2). DNA was also examined for rearrangement of the immunoglobulin heavy chain using a probe to the heavy-chain joining region (J^sub H^, manufactured by Philip Leder9) after digestion with HindIII (Amersham Pharmacia Biotech), BamHI/HindIII, EcoRI, and BglII. No evidence of a monoclonal B-cell lymphocyte population in the specimen by Southern hybridization analysis was noted.

Cytogenetic Analysis

Cytogenetic analysis was performed on the marrow aspirate using standard G-banding technique. Four of 20 metaphases were analyzed revealing a complex karyotype, 46, XY,del(2)(q13),t(3;22)(q21;q11.2),der(11)add(11) (p11.2),del(11)(q22q23),inv(14)(q11.2q32),-18,+mar[7]/ 46,idem,i(8)(q10) [7] /46,XY,[6].

COMMENT

T-cell prolymphocytic leukemia is a rare disorder characterized by hepatosplenomegaly, lymphadenopathy, anemia, thrombocytopenia, and lymphocyte counts greater than 100 × 10^sup 3^/µL.1 Matutes et al3 studied clinical and laboratory features of 78 cases of T-PLL. The main symptoms reported were splenomegaly (73%), lymphadenopathy (53%), hepatomegaly (40%), and skin lesions (27%). Seventy-five percent of their patients had a high leukocyte count (greater than 100 × 10^sup 3^/µL). In addition, 15 (19%) of their patients were classified as having the small cell variant of T-PLL. These latter patients did not show any difference in clinical and laboratory features from patients with classic T-PLL.

The lymphocytes in T-PLL are small to medium sized, with nongranular basophilic cytoplasm. The nuclei are round, oval, or occasionally markedly irregular with a visible nucleolus. In the small cell variant of T-PLL, the cell size is small, and the nucleolus is evident only by electron microscopy.1-3

T prolymphocytes are mature postthymic T cells that are TdT and CDIa negative and CD2, CD3, and CD7 positive. In 60% of cases of T-PLL, the cells are CD4+ and CDS-, and in 15% they are CD4- and CDS+. A unique feature of T-PLL in 25% of cases is coexpression of CD4 and CDS. T-cell prolymphocytic leukemia is characterized by clonal rearrangement of T-cell receptor β and γ chains.1,3 Cytogenetic studies indicate that 80% of patients with T-PLL show inversion of chromosome 14 with breakpoints in the long arm at q11 and q32. A reciprocal translocation t(14;14)(q11;q32) is present in 10% of patients. Abnormalities of chromosome 8, idic(8p11), t(8;8)(p11-12;q12), and trisomy 8q are seen in 70% to 80% of cases. Deletions at 12pl3 and 11q23 and t(X;14)(q28;qll) can also be found in patients with T-PLL.1-3-4 In the aforementioned series of 78 cases of T-PLL reported by Matutes et al,3 76% of patients showed inv(14) with breakpoints at qll and q32, and 53% of patients had trisomy 8, including isoSq. One of their cases showed t(ll;14)(13;q32), and one had a normal karyotype. Additional unusual chromosomal rearrangements such as der(6)t(X;6)(p!4;q25), der(13)t(13; 14)(q22;qll), t(5;13)(q34;pll), r(17)(p!3;q21), and t(17; 20)(q21;ql3) have also been described.10

Based on morphologic evaluation alone, the small cell variant of T-PLL may be confused with B-cell chronic lymphocytic leukemia. In addition, there is confusion regarding whether T-cell chronic lymphocytic leukemia (T-CLL) is a true entity. T-cell chronic lymphocytic leukemia was first used to designate an indolent disease with circulating granular lymphocytes, now widely referred to as T-cell large granular lymphocytic leukemia.11 Hoyer et al11 described 25 cases of T-CLL with predominantly small lymphocytes having absent or small and inconspicuous nucleoli. The authors of this study concluded that T-CLL is distinct from T-PLL and can be morphologically similar to B-cell chronic lymphocytic leukemia. However, it has been suggested that the term T-CLL should be discarded.12 T-cell chronic lymphocytic leukemia is now widely considered to represent the small cell variant of T-PLL, based on similar presenting features and aggressive clinical course, similar ultrastructural features including nucleoli and a consistent chromosomal abnormality, and inv14 with similar breakpoints in 14qll and 14q32.11 World Health Organization histologie classification of mature T-cell and natural killer cell neoplasms does not include T-CLL as a distinct entity.13

In addition to the cytogenetic findings previously reported in the literature, our patient presented with t(3; 22)(q21;11.2),-18 and +mar[7], which, to our knowledge, have not been previously reported in patients with T-PLL. Instead, t(3;22)(q21;11.2) has been reported in cases of acute myeloid leukemia evolving from myelodysplastic syndrome, chronic myeloid leukemia, and non-Hodgkin lymphoma.5 To our knowledge, this is the first reported case of T-PLL presenting with t(3;22)(q21;11.2).

Our patient also had an elevated serum β^sub 2^-microglobulin level. β^sub 2^-Microglobulin is a small protein of molecular weight 11 800 that is found on the surface of nucleated cells as the noncovalent associated light chain of the class I HLA antigen. Although present on all cells, serum β^sub 2^-microglobulin concentration mainly reflects proliferation or turnover of lymphocytes. Serum β^sub 2^-microglobulin reflects the total burden of malignant cells mainly in malignant myeloma and B-cell chronic lymphocytic leukemia.6,7 In non-Hodgkin lymphoma, significant high values of β^sub 2^-microglobulin are reported in widespread disease and high-grade histology. With regard to Hodgkin lymphoma, lower β^sub 2^-microglobulin levels are reported compared with cases of non-Hodgkin lymphoma. Elevated serum β^sub 2^-microglobulin is also described in cases of adult T-cell leukemia. Lower pretreatment serum β^sub 2^-microglobulin values may predict a greater response to chemotherapy and increased survival in cases of B-cell chronic lymphocytic leukemia and adult T-cell leukemia.6,7,14 In acute lymphoblastic leukemia, β^sub 2^-microglobulin is only slightly elevated, most likely because of the poorly differentiated state of lymphoblasts.6 The significance of β^sub 2^-microglobulin has not been specifically discussed in the literature in relation to T-PLL. It is important to exclude other conditions that are associated with elevated serum β^sub 2^-microglobulin, including decreased renal clearance and acute or chronic inflammation. Our patient did not have any of these conditions. Therefore, to our knowledge, this is first reported case of T-PLL associated with elevated serum β^sub 2^-microglobulin.

Considering the age of the patient, moderate leukocytosis, and absence of hepatosplenomegaly and lymphadenopathy no chemotherapy was given to the patient. The patient was treated with recombinant erythropoietin, which resulted in improvement of his general condition and hematocrit. His white blood cell count is stable 12 months after the diagnosis of T-PLL. Some rare cases of indolent T-PLL have been described in the literature.2,15 However, no features have been described as possible prognostic indicators in T-PLL. We, therefore, report what is to our knowledge the first case of T-PLL with an apparently indolent clinical course and unique association of t(3;22)(q21;11.2) and elevated serum β^sub 2^-microglobulin. Further studies are needed to determine the potential prognostic value of t(3;22)(q21;11.2) and elevated serum β^sub 2^-microglobulin in patients with T-PLL.

References

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2. Shichishima T, Kawaguchi M, Machi T, et al. T-prolymphocytic leukemia with spontaneous remission. Br J Haematol. 2000;108:397-399.

3. Matutes E, Bro-Babapulle V, Swansbury J, et al. Clinical and laboratory features of 78 cases of T-prolymphocytic leukemia. Blood. 1991,-78:3269-3274.

4. Bro-Babapulle V, Pomfret M, Matutes E, et al. Cytogenetic studies on prolymphocytic leukemias, II: T cell prolymphocytic leukemia. Blood. 1987;70:926931.

5. Yamamato K, Nagata K, Tsurukubo Y, et al. A novel translocation t(3;22) (q21;q11) involving 3q21 in myelodysplastic syndrome-derived overt leukemia with thrombocytosis. Leuk Res. 2000)24:453-457.

6. MeIIiIo L, Musto P, Tomasi P, et ai. Serum beta 2-microglobulin in malignant lymphoproliferative disorders. Tumori. 1988;74:129-135.

7. Everaus H, Luik E, Lehtmaa J. Active and indolent chronic lymphocytic leukemia: immune and hormonal peculiarities. Cancer lmmunol lmmunother. 1997;45:109-114.

8. Weiss LM, Wood GS, Ellisen LW, Reynolds TC, Sklar ). Clonal T-cell populations in pityriasis lichenoides et varioliformis acuta (Mucha-Habermann disease). Am 1 Pathol. 1987;126:41 7-421.

9. Hieter PA, Maizel JVJr, Leder P. Evolution of human immunoglobulin kappa J region genes. J Biol Chem. 1982;257:1516-1522.

10. Zver S, Vokac NK, Zagradisnik B, et ai. T cell prolymphocytic leukemia with new chromosomal rearrangements. Acta Haematol. 2004;111:168-1 70.

11. Hoyer JD, Ross CW, Li CY, et al.TrueT-cell chronic lymphocytic leukemia: a morphologic and immunophenotypic study of 25 cases. Blood. 1995;86:11631169.

12. Matutes E, Catovsky D. CLL should be used only for the disease with Bccll phenotype. Leukemia. 1993;7:917-918.

13. Jaffe ES, Ralfkiaer E. Mature T-celI and NK-cell neoplasms: introduction. In: Jaffe ES, Harris NL, Stein H, Vardiman JW, eds. Pathology and Genetics of Tumours of Hematopoietic and Lymphoid Tissues. Lyon, France: IARC Press; 2001:191-194. World Health Organization Classification of Tumours; vol 3.

14. Sadamori N, Mine M, Hakariya S, et al. Clinical significance of beta 2-microglobulin in serum of adult T-cell leukemia. Leukemia. 1995;9:594597.

15. Soma L, Cornfield DB, Prager D, et al. Unusually indolent T-cell prolymphocytic leukemia associated with a complex karyotype: is this T-cell chronic lymphocytic leukemia? Am I Hematol. 2002;71:224-226.

Farah Moid, MD; Estella Day, MT(ASCP); Maria A. Schneider, MD; Kenneth Goldstein, MD; Louis DePalma, MD

Accepted for publication May 13, 2005.

From the Department of Pathology (Drs Moid and DePalma), and the Clinical Laboratories (Ms Day), George Washington University Hospital, Washington, DC. Drs Schneider and Goldstein are in private practice in Washington, DC.

The authors have no relevant financial interest in the products or companies described in this article.

Reprints: Louis DePalma, MD, Department of Pathology, 900 23rd St NW, George Washington University Hospital, Washington, DC 20037 (e-mail: ldepalma@mfa.gwu.edu).

Copyright College of American Pathologists Sep 2005
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