Granulocytic Sarcoma

Abstract

Because of shared histologic and clinical features, granulocytic sarcoma (GS) may be confused with B- and T cell malignant lymphomas. Antibodies to myeloperoxidase, lysozyme, CD 15, and other determinants may correctly identify GS but are usually not part of the standard panels employed to evaluate a suspected non-Hodgkin's lym phoma. At the authors' institutions, these typically include reagents to CD20, CD43, CD45, CD45RO, and MB2. In this analysis, well-documented cases of GS and histologi cally similar lymphomas were assessed using a standard immunohistologic antibody panel employed in evaluation of putative lymphomas. In addition, antibodies to lyso zyme, myeloperoxidase, CD3, CD15, CD34, CD68, and MAC 387 were used in a second tier of analysis. The results were evaluated in a step-wise fashion. All B cell lymphomas and the majority of T cell cases were identified correctly by their reactivity for CD20 and CD45RO, respectively. Using the five standard lymphomas markers, 12 of 19 cases of GS had a phenotype that would be relatively unusual in non-Hodgkin's lymphoma—as reflected by CD43 and MB2 coexpression without CD20 or CD45RO-whereas 7 cases of GS showed a "CD43-only" phenotype and were there fore considered possible T cell lesions. All 19 GS cases were labeled by at least one second-tier marker and 18 exhibited two or more of these determinants at that level of evaluation. All T cell lymphomas failed to express CD 15, CD34, CD68, or MAC 387; however, 3 of 20 B cell tumors were focally positive for CD 15. CD3 labeled 9 of 11 cases of T cell lymphoma but also was seen in 11 of 16 cases of GS. These results indicate that, in suspected lymphoma cases, CD45-positivity, but failure to express CD20 or CD45RO, suggests the possibility of GS. Additional immunohistologic studies, in particular those for lysozyme or myeloperoxidase, can then be used to further define the tumoral lineage. Int J Surg Pathol 2(3):177-186, 1995