Extramedullary myeloid tumour (EMMT) of the gallbladder

Abstract

This report describes a rare case of an extramedullary myeloid tumour (EMMT) of the gallbladder in a patient without leukaemia. A 33 year old man visited a local hospital because of jaundice. Abdominal computed tomography revealed a tumorous mass measuring 6.0 x 4.5 cm and involving the entire gallbladder. A percutaneous needle biopsy was attempted, but because adenocarcinoma could not be completely ruled out, the use of undue force was considered dangerous. Under a preoperative diagnosis of gallbladder carcinoma, a hepatopancreatoduodenectomy was performed. The tumour cells exhibited various amounts of eosinophilic cytoplasm, had medium sized round nuclei with indentation and grooving, and were strongly immunoreactive for myeloperoxidase, CD43, and c-kit protein (CD117). After surgery, the patient underwent combination chemotherapy as prescribed for cases of acute myeloblastic leukaemia. The patient did not develop acute leukaemia during a follow up period of four years. In conclusion, a correct diagnosis of EMMT can be made using appropriate immunohistochemical staining.

Figure 1

(A) Abdominal computerised tomography image showing partial infiltration of the tumour into the gallbladder wall but no sign of invasion of the liver or portal vein. (B) Macroscopically, the gallbladder lumen is filled with blood and degenerative tissue, and the cut surface of the tumour has a nodular, well circumscribed, glistening appearance.

Figure 2

(A) The tumour cells have various amounts of eosinophilic cytoplasm and are arranged in a trabecular to sheet-like pattern (haematoxylin and eosin (H&E) stain; original magnification, ×400). (B) Most of the gallbladder epithelium is not involved (H&E stain; original magnification, ×40). The tumour cells show diffuse and strong reactivity for (C) myeloperoxidase and (D) CD43 (original magnification, ×400).