Granulocytic sarcoma with pulmonary involvement

A 42-year-old man presented with a 6-month history of cough, weight loss, and progressive dyspnea. His white blood count was 7,000/ml, 24% of which were found to be blasts on the peripheral blood film. A bone marrow examination revealed 20% of the cells to be immature, blast-like forms (See Image 1). The morphology of these cells was thought to be most consistent with acute myeloid leukemia (FAB M1/M2). Cytogenetic analysis revealed an 8;21 translocation. A computed tomography scan of the chest demonstrated a mass in the right hilum extending to the mediastinum and compressing the bronchi in the right middle and right lower lobes (See Image 2). A bronchoscopy was performed, and the morphologic appearance of the transbronchial biopsy specimen was initially felt to be most consistent with small cell carcinoma (See Image 3). However, subsequent special stains of this specimen were positive for myeloperoxidase (See Image 4), thereby establishing the diagnosis of a granulocytic sarcoma. The cells in the lung biopsy were also found to be CD34 positive, thereby providing further confirmation of this diagnosis. The lung mass was first treated with local radiotherapy (200 cGy 2), resulting in a rapid clinical improvement. The patient next received given combination chemotherapy that led to a complete hematologic remission along with a further decrease in the size of the lung mass. Finally, after two courses of consolidation therapy followed by a conditioning regimen of busulfan and cytoxan, an autologous bone marrow transplant was performed. The patient remains in complete remission at this time, now 2 months post transplantation. Granulocytic sarcoma is an extramedullary solid tumor composed of immature myeloid cells. It may occur in conjunction with myeloid leukemia or as an isolated phenomenon, and it can involve any organ. When it is initially found, a granulocytic sarcoma can be misdiagnosed as a malignant lymphoma. As in this case, granulocytic sarcoma is often associated with an 8;21 translocation. Pulmonary involvement by granulocytic sarcoma is rather uncommon and may indicate a relatively poor prognosis.