Granulocytic sarcoma presenting as a retroperitoneal lymph node mass - A case report with diagnosis by fine needle aspiration biopsy and flow cytometry

BACKGROUND: Granulocytic sarcoma is a localized tumor of myeloblasts occurring at an extramedullary site. It is a rare lesion and may be confused with large cell lymphoma on fine needle aspiration biopsy. CASE: This case demonstrated a rare case of granulocytic sarcoma presenting as a retroperitoneal lymph node mass. Diagnosis was made by a combination of fine needle aspiration cytology and flow cytometry. CONCLUSION: The cytologic features of granulocytic sarcoma are indicative of the correct diagnosis, but confusion between this lesion and large cell lymphoma may occur. Flow cytometric studies may be quite useful in arriving at the correct diagnosis.