Age / Sex : 37 / M

Age / Sex : 50/Female

Chief complaint: Left shoulder pain

fibromatosis

Discussion

Findings: Axial T1WI shows a low signal intensity lobulated mass on the left triceps and deltoid muscles. Axial fat-suppressed T2WI shows an ill-defined heterogeneous mass containing mixed signal intensity. Axial fat-suppressed contrast-enhanced T1WI demonstrates intense enhancement of the mass.

Differential Diagnosis: fibrous-type low-grade sarcomas, such as very-low-grade leiomyosarcoma and fibrosarcoma

Diagnosis: Fibromatosis

Discussion:

Fibromatosis is composed of spindle-shaped fibrous cells that are separated and surrounded by abundant collagen material with rare mitoses. Their biologic behavior is intermediate in aggressiveness between benign fibrous lesions and fibrosarcoma.

There is a strong tendency toward local recurrence; however, these lesions never metastasize.

It can be divided into two major groups: superficial and deep. The superficial fibromatoses are typically small, slow-growing lesions and include palmar fibromatosis, plantar fibromatosis, juvenile aponeurotic fibroma, and infantile digital fibroma. The deep fibromatoses are commonly large, may grow rapidly, and are more aggressive. They include infantile myofibromatosis, fibromatosis colli, extraabdominal desmoid tumor, and aggressive infantile fibromatosis.

Extraabdominal Desmoid Tumor is most commonly affected between the ages of 25 and 35 years. The extremities account for approximately 70% of cases. Frequent sites of involvement include the shoulder (20%), chest wall and back (15%), thigh (12%), mesentery (10%), neck (10%), and knee (7%).

Most cases manifest as solitary lesions; however, synchronous multicentric lesions in the same extremity occur in approximately 10%–15% of cases.

The prognosis appears to be related to the age of the patient. Patients under the age of 30 years tend to have more aggressive lesions. The local recurrence rate is high in these patients (up to 87%). The recurrence rate in patients older than 20 years is approximately 50%.

Calcification is uncommon. Underlying bone involvement is seen in 6%–37% of patients, typically with pressure erosion and cortical scalloping but without invasion of the medullary canal. In Bone scintigraphy, it usually demonstrates increased uptake on blood pool and static images.

Extraabdominal Desmoid Tumor is typically intermuscular lesions, although muscle invasion is common. In addition, linear extension along fascial planes is a frequent manifestation. It is known that the lesions have decreased signal intensity on both T1- and T2-weighted images. The lesions with hypocellularity and abundant collagen had decreased signal intensity on T2-weighted images. However, some lesions with marked cellularity showed high signal intensity on T2-weighted images.

The deep fibromatoses typically demonstrate moderate to marked enhancement after administration of gadolinium contrast material, particularly in less collagenized and more cellular regions

References:

1.R.R. Robbin, M.D. Murphey, H.T. Temple, M.J. Kransdorf and J.J. Choi, Imaging of musculoskeletal fibromatosis. Radiographics 21 (2001), pp. 585–600.

2.Kobayashi H, Kotoura Y, Hosono M, Tsuboyama T, Sakahara H, Endo K, Konishi J..

MRI and scintigraphic features of extraabdominal desmoid tumors Clinical imaging 21(1997), pp.35-39.