Desmoid-type aggressive fibromatosis - shoulder

Case contributed by Dr Dalia Ibrahim

Presentation

Left shoulder recurrent swelling after surgical excision of a soft tissue shoulder lesion 2 years ago.

Patient Data

Age: 45 years
Gender: Male

The left trapezius muscle is swollen by virtue of large soft tissue mass lesion showing mild increased FDG uptake with SUV max 5. The mass is rather homogenous showing internal faint linear enhancement. It's also involving the levator scapulae muscle. It's smoothly abutting the adjacent scapula and clavicle bones with no erosive or lytic changes.

The mass elicits heterogeneous signal with internal bands of persistent low signal on all pulse sequences. The lesion shows moderate enhancing areas in the non-dark cellular areas.

Pathology after surgical excision reveals fibromatosis.

Case Discussion

This is a pathologically proven case of desmoid-type aggressive fibromatosis involving the trapezius muscle. Desmoid-type fibromatosis or aggressive fibromatosis is an aggressive fibroblastic tumor.

The case presented typical MRI features of desmoid-type fibromatosis including:

  • It showed reduced T2 signal secondary to high collagen contents with linear bands of persistent dark signal (band sign), however, this band sign is not very specific as it could be seen in giant cell tumor of the tendon sheath and myxofibrosarcoma.
  • It also shows nonaggressive criteria on the adjacent bony structures on CT and MRI.
  • It shows mild increased FDG uptake on the PET-CT study.

 

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