Case 95-2

History/Physical Findings:

A 9-month-old boy was presented to his pediatrician because of a 2 X 1 cm purple nodule on his right neck. Beginning as a small blue spot, the lesion reportedly grew in size over a two to three month period. Although initially thought to be a probable hemangioma, possibly thrombosed, the firm, mobile, circumscribed, subcutaneous mass was suspicious and was surgically removed. The child was afebrile without hepatosplenomegaly or other soft tissue masses.

Surgical Pathology:

Gross:

Microscopic:

Summary of immunologic studies performed on tissue sections:

           CD 20     -         CD 45               +
            CD 3      -         CD 68               +
            CD 2      -         CD 74               +
            CD 5      -         Lysozyme            +
            CD 45RO   -         MAC 387             +
            CD 43     +         S-100               -
            Neutrophil elastase -

Flow cytometric analysis of cell suspension from neck mass biopsy:

                   Percent



            CD 19           1
            CD 7           99
            CD 13          97
            CD 33          98
            CD 14          84
            CD 45          91

Bone Marrow Aspirate: Normocellular marrow without increase in blast count.

Based on the above findings, what is your diagnosis?

Discussion:

Flow cytometry studies of a cell suspension from the biopsy were positive for CD 45 (LCA), CD 14 (a monocyte marker), CD 13, and CD 33 (markers of myeloid differentiation), and CD 7 (a T cell marker also frequently found on myeloid cells). Tissues sections (illustrated above) were positive for CD 43, an antigen typically found on T cells but also on myeloid cells and some malignant B cell populations. Tumor cells were also positive for CD 68, CD 74, Lysozyme and MAC 387. Although CD 7 is frequently found on otherwise typical myeloid leukemias, its presence raised the question of a mixed lineage leukemia. Lack of staining for other pan T cell markers, CD 2, CD 3, and CD 5, as well as negative staining for the B cell markers CD 19 and 20 were evidence to rule out this consideration.

While extramedullary myeloid cell tumors (EmMCT) also known as granulocytic sarcoma or chloroma may be seen at almost any age, they are most common in children. The diagnosis of EmMCT in a nonleukemic patient must be differentiated from malignant lymphoma - usually either large cell or lymphoblastic lymphoma. Immunohistology as in this case can play a key role in distinguishing acute lymphoblastic leukemia/lymhoblastic lymphoma from myeloid sarcomas. (1) Although most studies indicate progression of EmMCT to acute myeloid leukemia within one year, in one series, four of sixteen patients failed to develop acute leukemia in follow-up periods ranging from 3.5 to 16 years. (2) The presence of antigens associated with monocytic lineages suggest a typical acute myelomonocytic leukemia, (FAB M4 subtype).

Extramedullary myeloid cell tumors precede the development of AML in approximately 40% of cases but also may occur concurrent with presentation or relapse of AML and may also occur in association with CML. (3)

Diagnosis:

References:

1. Quintanilla-Martinez L, Zukerberg LR, Ferry JA, Harris NL: Extramedullary tumors of lymphoid or myeloid blasts. Am J Clin Pathol, 104:431-443, 1995.

    

    

2. Meis JM, Butler JJ, Osborne BM, Manning JT: Granulocytic sarcoma in nonleukemic patients. Cancer, 58:2697-2709, 1986.

    

    

3. Neiman RS, Barcos M, Berard C: Granulocytic sarcoma. Cancer, 48:1426-1437, 1981.

    

    

Contributors:

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

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

Guy E. Nichols, M.D., Ph.D.
Department of Pathology
University of Virginia Health System

Eugene McGahren, M.D.
Department of Surgery
University of Virginia Health System

Questions should be addressed to