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Contributed by George Pirumyan, M.D., M.P.H. and Nasir Bakshi, M.D. Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK. Last updated on June 10, 2007.

 Peripheral Blood and Bone Marrow / Case 6  The patient is a 50 year-old male who presents with PCP pneumonia, generalized lymphadenopathy, hepatosplenomegaly, skin rash, increased WBC, high LDH and hypercalcemia. The followings are representative data and images:

Diagnosis: Adult T-cell lymphoma/leukemia (ATLL)

Discussion: The peripheral blood smear shows highly pleomorphic medium sized to large lymphoid cells, with polylobated nuclei and coarsely clumped chromatin as illustrated here. Often those cells are referred as “flower cells” or clover leaf cells. Occasionally prominent nucleoli can be seen, as it is present in this picture. Giant cells with convoluted or cerebriform nuclear contours may also be seen.

Immunophenotypically, the tumor cells express T-cell markers including CD2, CD3, CD5 but CD7 antigen is characteristically not expressed.  CD25 (Interleukin-2 receptor) is over expressed in most of the cases of adult T-cell leukemia/lymphoma. CD4 is usually positive but CD8 is far less commonly expressed. However in rare case dual expression of CD4 and CD8 can be observed.

The disease is usually widely disseminated at the time of presentation, with widespread involvement of lymph nodes. The skin is the most common extra lymphatic site of involvement. Bone marrow involvement in cases of adult T-cell leukemia/lymphoma is usually patchy and degree of bone marrow involvement does not correlate with the number of circulating neoplastic cells. Four distinct clinical variants of this entity are recognized: acute, lymphomatous, chronic and smoldering. Adult T-cell leukemia/lymphoma  is strongly associated with human T-cell leukemia virus 1 (HTLV-1).

Morphologically sezary cells can resemble ATLL although the sezary cells are smaller in size and have distinctive cereberiform nuclear outlines best seen on high magnification. CD25 is not expressed in sezary cells but is hallmark of ATLL. Rarely carcinoma cells can be identified in the peripheral smear. Carcinoma cells, however, are somewhat larger in size and typically are present in clumps mostly toward the tail end of the smear. The morphologic features along with the immunophenotype of the case are unlike that of a circulating NK-cell leukemia. Finally in suspected/doubtful cases serological confirmation of HTLV-1 is essential to establish the diagnosis of ATLL.