Granulocytic sarcoma presenting as a thrombosed external hemorrhoid in a patient with myelodysplastic syndrome overt leukemia.

A 67-year-old Japanese man complained of a painful lump in his anus. He had a 15-month history of myelodysplastic syndrome (MDS) and had been diagnosed with MDS overt leukemia. A solid lump measuring 1.0 cm in diameter was detected in the anal verge. Under a diagnosis of a thrombosed external hemorrhoid, thrombectomy was performed under local anesthesia. One week after thrombectomy, the wound had not healed, and grayish-green tissue was seen at the bottom. A biopsy of the wound revealed atypical mononuclear cell infiltration. Myeloperoxidase and lysozyme were positive on immunohistochemical staining. Finally, the diagnosis of granulocytic sarcoma (GS) was made. Though it is well known that perianal complications occur quite often in patients with leukemia, it is unusual for a diagnosis of GS of the anus to be definitely established. To our knowledge, there has not been a previous report of GS presenting as a thrombosed external hemorrhoid. The development of GS should be considered during the management of such lesions, especially in patients with bone marrow disorders, such as acute myeloid leukemia (AML) or high-risk MDS.