Extra medullar Granulocytic sarcoma: a case report of an exceptional localization

Granulocytic sarcoma is a rare type of tumor composed of extramedullary immature cells. The breast location is very rare; it accounts for less than 8% of cases. The present study reports the case of a 36-year-old female with a medical history of myelodysplastic syndrome. She was referred because of a lump in the left breast. We have diagnosed a case of granulocytic sarcoma of the breast by core biopsy. Histology and immunohistochemistry showed hypercellular smears with immature myeloid cells. The blast cells were myeloperoxidase positive. The patient underwent a lumpectomy. Five months later, she developed a contralateral recurrence, treated by lumpectomy and radiotherapy. Three years later, she developed a recurrence in the left knee. We report this case for its rarity and as a note of caution to a physician to consider myeloid sarcoma in the differential diagnosis of a breast lump, to provide the correct diagnosis and avoid incorrect treatment of a curable disease.