T-Cell Prolymphocytic Leukemia Involving Extramedullary Sites

Jose R. Valbuena, MD; Marco Herling, MD; Joan H. Admirand, MD; Anthony Padula, MD; Dan Jones, MD, PhD; L. Jeffrey Medeiros, MD

Disclosures

Am J Clin Pathol. 2005;123(3):456-464. 

In This Article

Abstract and Introduction

T-cell prolymphocytic leukemia (T-PLL) can involve extramedullary sites, but the diagnosis is usually established by examination of blood and bone marrow. As a result, the histologic findings at extramedullary sites are poorly documented in the literature. We describe 19 extramedullary biopsy specimens from 14 patients with T-PLL. Skin (n = 10) was the most common site biopsied. T-PLL surrounded dermal blood vessels and appendages (n = 6), diffusely replaced dermis (n = 3), or formed a subcutaneous mass (n = 1). Other extramedullary sites included liver and lymph nodes (3 each) and spleen, lung, and cecum (1 each). In liver and lymph nodes, the neoplasm predominantly involved portal tracts and paracortex, respectively. Cytologically, the T-PLL cells were round (n = 16) or Sézary cell–like (n = 3). Nucleoli were observed in a subset of cells in 8 specimens and were prominent in 3 specimens. Immunostaining for T-cell leukemia–1 (TCL-1) was positive in specimens from 9 (64%) of 14 patients. We conclude that the prolymphocytoid features of T-PLL cells can be difficult to detect in routinely stained sections of extramedullary biopsy specimens. TCL-1 expression can aid in diagnosis at extramedullary sites.

T-cell prolymphocytic leukemia (T-PLL) is the most common type of mature T-cell leukemia and is characterized by a rapidly rising peripheral blood lymphocyte count, bone marrow involvement, and splenomegaly.[1] The disease in most patients follows an aggressive clinical course, but a subset of patients initially can have an indolent clinical course, up to approximately 25% in 1 study.[2] In peripheral blood or bone marrow aspirate smears, T-PLL cells are slightly larger than normal lymphocytes, and, commonly, each cell has a prominent nucleolus, irregular nuclear contours, and moderately abundant, nongranular and basophilic cytoplasm with protrusions or blebs.[1,2] However, small cell and cerebriform cell variants of T-PLL also are described.[2] Immunophenotypically, T-PLL cells are of mature T-cell lineage, positive for T-cell markers, and negative for terminal deoxynucleotidyl transferase (TdT). The neoplastic cells usually are positive for CD4, although cases positive or negative for both CD4 and CD8 also are reported.[1]

Previous studies of T-PLL have emphasized the clinical characteristics of this disorder and the morphologic findings in peripheral blood and bone marrow.[3,4] Few reports have focused on the histologic findings of T-PLL involving extramedullary sites. In this study, we describe the pathologic findings of T-PLL involving 19 extramedullary biopsy specimens obtained from 14 patients.

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