Nodular fasciitis

Case contributed by Dr Matt A. Morgan

Presentation

Atraumatic left shoulder pain

Patient Data

Age: 25 years
Gender: Female
X-ray

Initial radiographs

There is an exophytic calcified ovoid mass projecting posterolaterally from the proximal humeral shaft, measuring approximately 3.3 cm in length, with what appears to be associated periosteal thickening.

The mass was percutaneously biopsied which revealed "Spindle cell proliferation with metaplastic ossification, favor benign/reactive." 

FISH DNA Break-apart signal analysis for detection of USP6 translocation showed positive Break-apart signals in a large subset of the lesional spindle cells (50%). The finding implicates translocation involving USP6 and supports the diagnosis of nodular fasciitis with ossification/myositis ossifican or soft tissue ABC.

Follow up imaging was recommended.

X-ray

Radiographs obtained three months later...

The mass has decreased in size over three months.

X-ray

Radiographs were later obtained that were performed two months prior to initial exam...

Normal -- no mass two months prior.

Case Discussion

This case is a good example of how some benign osseous processes can mimic malignancy.

The initial images show an exophytic calcified mass and there was at first a concern for malignancies such as parosteal osteosarcoma or periosteal chondrosarcoma.

On biopsy, however, no malignancy was found, and the mass has decreased in size over time. The overall appearance and presentation is compatible with nodular fasciitis.

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Case information

rID: 86089
Published: 19th Jan 2021
Last edited: 20th Jan 2021
Inclusion in quiz mode: Excluded
Institution: University of Pennsylvania

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