Primary intra-osseous myoepithelioma of phalanx mimicking an enchondroma

Myoepithelial carcinoma of tibia mimic giant cell tumor: a case report with emphasis on MR features

Intraosseous myoepithelial carcinoma is an extremely rare type of bone tumor that most often presents in the long tubular bones, but also occurs in small tubular bones and the axial skeleton. We report the radiographic images and complete magnetic resonance (MR) features of a 44-year-old male with right knee pain of 7 months' duration. The radiographic findings and convention MR images indicated a giant cell tumor of the bone. The dynamic contrast-enhanced images showed a patent with the early wash-in and early wash-out usually noted in a giant cell tumor of the bone. Only water restriction on diffusion-weighted imaging (DWI) showed the malignant impression. Care should be taken when conventional images indicate giant cell tumor of the bone, as intraosseous myoepithelial carcinoma, although rare, can mimic this more common diagnosis. Further studies with DWI are warranted.

Myoepithelioma of the lateral abdominal wall: A case report

RATIONALE

Soft-tissue myoepithelioma is a rare neoplasm. It usually occurs in the distal or proximal extremities, but seldomly arises in the abdominal wall.

PRESENTING CONCERNS OF THE PATIENT

The patient is a 40-year-old woman who presented with a painless mass at the lateral abdominal wall for 6 months. Computed tomography scan revealed a lobulated and well-defined iso-density mass showing heterogeneously moderate enhancement. The mass exhibited intermediate T1 signal and obvious high T2 signal on magnetic resonance imaging.

INTERVENTIONS

The tumor was excised. Hematoxylin-eosin stain and immunohistochemical stain showed that the tumor was myoepithelioma.

OUTCOMES

The patient did not undergo chemotherapy and radiotherapy. No recurrence or metastasis was noted during the 1 year follow-up.

LESSONS

Radiologists should consider myoepithelioma in the differential diagnosis when finding a tumor in the abdominal wall.

Myoepithelial Tumors of Bone

Myoepithelial tumors (METs) of bone (BMETs) are a rare but distinct tumor entity. METs that are cytologically benign are termed myoepitheliomas; METs with malignant histologic features are called myoepithelial carcinomas. BMETs have a wide age range, may involve any part of the skeleton, and have a variable spindle cell and epithelioid morphology. Bone tumors to be considered in the differential diagnosis are discussed. Additional techniques are indispensable to correctly diagnose BMETs. By immunohistochemistry, BMETs often express cytokeratins and/or EMA together with S100, GFAP, or calponin. Half of BMETs harbor EWSR1 (or rare FUS) gene rearrangements with different gene partners.