Abstract
Granulocytic sarcoma is a rare mass forming extra-medullary manifestation of myeloid leukemic cells. It presents concurrently with acute myeloid leukemia or can precede an acute leukemic stage. We report a case of myeloid sarcoma in a 55-year-old woman who presented with a newly formed indurated violaceous nodule on the chest. Biopsy revealed discohesive cords of pleomorphic cells with amphophilic cytoplasm, vesicular nuclei and marked nuclear atypia in the dermis. The atypical cells were focally associated with a myxoid matrix and infiltrated between adnexal structures along with bizarre giant cells. Immunohistochemical staining for CD34 highlighted scattered cells and was negative for pan-keratin, S100, ALK, CD30, and desmin. The case was initially signed out as atypical fibro-histiocytic neoplasm with a recommendation to re-excise. The re-excision specimen showed identical morphology and immunophenotypic expression as the initial biopsy. At this point, the treating dermatologist contacted the oncologist and relayed the patients extensive history of myeloproliferative disorder to the dermatopathology service. An expanded IHC profile was implemented. The multinucleated cells were strongly positive for CD61, consistent with megakaryocytic differentiation. The CD34+ cells were highlighted with CD71 and myeloperoxidase, confirming erythroid and myeloid lineage. The diagnosis was amended to myeloproliferative disorder with blast transformation. Our case illustrates that myeloid sarcoma be included in the differential diagnosis of lesions with bizarre giant cells, and also highlights fibro-histiocytic lesions as a diagnostic pitfall. It emphasizes the importance of inter-hospital communication and clinic-pathological correlation, given that this patients history of myeloproliferative disorder was key to achieving an accurate diagnosis.
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