Case 95-1

History/Physical Findings:

A 69-year-old woman with a history of diabetes mellitus complained of weakness and weight loss. The patient was without hepatosplenomegaly, lymphadenopathy, or other palpable masses.

Laboratory Findings:

Because of pancytopenia, a bone marrow aspirate was performed.

Micro:

Bone marrow aspirate differential:

                   Marrow %      Peripheral Blood %
Blasts          46.0
Promyelocytes        1.0
Metamyelocytes       2.0
Bands            8.0            10
Neutrophils      6.0            50
Lymphocytes     18.0            38
Monocytes        0.0                       
Basophils                        2
NRBCs               19.0             8 

                     Percent
CD l9           50
CD 5             3
CD19+CD5+        1
CD 10           58
CD19+CD10+      47
CD 34            8
Cyto µ          Pos
CD 14            1
CD 45           34

Discussion:

The blasts seen in the bone marrow aspirate were moderate to large immature cells with coarsely granular nuclear chromatin and cytoplasmic vacuoles. Multiple nucleoli were noted. The cytoplasmic vacuoles stained positive for neutral lipids with Oil Red O.

Flow cytometry studies of the bone marrow aspirate were positive for CD 45, CD 19, and CD 10, but negative for CD 34. The cells were positive for cytoplasmic mu. This pattern, while not specific, is quite typical of Burkitt's lymphoma/leukemia or small noncleaved cell lymphoma. CD 19, 20, and 21 are usually positive on the blasts of Burkitt's, whereas CD 34 is absent. CD 10 expression is common (positive in up to 3/4 of cases).

This case is unusual in several aspects. Most patients present with Burkitt's lymphoma within the first two decades of life, however, cases are reported into the 9th decade. Although most often an extranodal proliferation, in the United States, Burkitt's lymphoma most commonly presents as an abdominal mass. This patient had no evidence of disease outside of the bone marrow. The cellular aspirate and high blast count suggest the extensive marrow involvement as is usual in reported cases of Burkitt's lymphoma of the marrow. Despite this degree of involvement, frankly leukemic peripheral blood involvement is uncommon. The virtually indistinguishable nature of a acute lymphoblastic leukemia (L3) and small noncleaved cell lymphoma is discussed in a recent review of 45 cases of L3 acute lymphoblastic leukemia in which it was concluded that the major difference between the two was clinical presentation. Non-Hodgkin's lymphoma as an isolated bone marrow finding is considered rare and often difficult to diagnose. None of the Ponzonni cases were small noncleaved cell lymphomas.

Diagnosis:

Malignant lymphoma, small noncleaved cell (Burkitt's lymphoma)/Acute lymphoblastic leukemia (L3).

References:

Brunning RD et al: Bone marrow involvement in Burkitt s lymphoma. Cancer 40:1771-1779, 1977.

Dayton VD: L3 acute lymphoblastic leukemia comparison with small non-cleaved cell lymphoma involving the bone marrow. Amer J Clin Path 101:130-139, 1994

Ponzoni M, Chin-Yang L: Isolated bone marrow non-Hodgkin s lymphoma: a clinical pathologic study. Mayo Clinic Proceedings 69:37-43, 1994.

Contributors:

David C. Winston, M.D., Ph.D. Department of Pathology University of Virginia Health System

Donald J. Innes, Jr., M.D. Department of Pathology University of Virginia Health System

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