Extra-abdominal fibromatosis - pectoral girdle

Case contributed by Jose Luis Carcamo
Diagnosis certain


Medical history of right shoulder mass 3 years ago, with recurrence after surgery.

Patient Data

Age: 50 years
Gender: Female

Round mass with defined contours which is shown in contact with the trapezius muscle and the supraspinatus muscle, with no evidence of infiltration.

The signal is isointense in relation to the muscles weight on T1 and hyperintense on T2 with high intensity high on T2 FAT sat, STIR and post-contrast.

Mass arterial supply probably comes from vertebral arteries.

This patient underwent another surgery, completely margin resection and ligation of arteries around the tumor, no infiltration of surrounding structures was seen.


Microscopic description: This tumor had 2 patterns, nodular fasciitis-like pattern and conventional pattern. It has Nodular formation containing spindle cells arranged in interlacing bundles, nuclear hyperchromasia, stromal hemorrhage, no mitotic activity was observed. Surgery margins of resection are at 1mm away from the lesion.

Case Discussion

Extra-abdominal fibromatosis (desmoid tumor) is a rarely observed benign tumor that represents less than 0.03% of all neoplasms and approximately 3% of all soft tissue lesions. It occurs more often in females (2:1 females:male) and has a higher incidence between puberty and the fourth decade of life (peak incidence 25–35 years).

The tumor may be primary or secondary to trauma, including surgery, or hormonal stimuli. Magnetic resonance imaging is the gold standard technique for diagnosis (showing margins/infiltration and bloody supply of the tumor).

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