Generalized lymphadenopathy as the first presentation of granulocytic sarcoma: a diagnostic challenge.

Introduction. Granulocytic sarcoma (GS), also known as chloroma or extramedullary myeloblastoma, is a solid tumor composed of primitive precursors of the granulocytic series that include myeloblasts, promyelocytes, and myelocytes. Granulocytic sarcoma is a rare tumor that may develop during acute myeloid leukemia (AML) but less frequently may precede its presentation. Although generalized lymph node enlargement is a presentation for malignant lymphoma, it can also rarely be the early presenting sign of GS. Methods. We present a case of GS mimicking lymphoma in a 45-year-old male. The patient presented with bilateral neck masses and had widespread, prominent lymphadenopathy secondary to AML as the first presenting manifestation of GS for the last 4 months with concurrent marrow AML. Result. A clinical diagnosis of lymphoma was suspected; fine needle aspiration cytology findings were also suggestive of lymphoma. However, peripheral blood and bone marrow examination reported as acute myeloid leukemia with monocytic differentiation and histopathology of excised lymph node confirmed it to be a GS not lymphoma. Conclusion. GS is often misdiagnosed as malignant lymphoma because of cytomorphologic and histologic similarities of the blasts to large cell lymphoma. A careful search for immature myeloid is a useful clue to the diagnosis accompanied with appropriate immunophenotyping.