ARRS COTW- October 15, 2018

BREAST IMAGING: Breast MRI

Case Author: Peter R. Eby, MD, Virginia Mason Medical Center

History

42-year-old woman with recent excision of desmoid fibromatosis with positive margins and a persistent palpable abnormality.

Imaging Findings

Targeted ultrasound image (A) of the right breast at the site of the palpable abnormality and previous excisional biopsy shows postsurgical architectural distortion with no discrete mass.

Axial (B) and sagittal (C) contrast-enhanced T1-weighted fat-saturated MR images show a focal area of clumped homogeneous nonmasslike enhancement anterior to the excisional biopsy cavity.

Computer-aided evaluation image (D) does not show enhancement that meets the color threshold in this area. Targeted second-look ultrasound images (E) confirm the presence of the seroma cavity but do not depict a sonographic abnormality corresponding to the MRI finding. MRI-guided biopsy was performed.

Diagnosis

Residual desmoid fibromatosis

Teaching Points

Problem-solving MRI can be useful for addressing specific clinical questions when all other imaging avenues have been exhausted. Problem-solving MRI should not be used when suspicious mammographic or sonographic findings have already been documented.

Breast MRI can be particularly useful for evaluating chest wall involvement of desmoid fibromatosis and for monitoring for residual or recurrent disease.

The appearance of desmoid fibromatosis at breast MRI is variable but has been reported as irregular and isointense to muscle on T1-weighted images. This condition can be difficult to differentiate from malignancy. The enhancement kinetics are generally a benign persistent pattern but have also been reported as plateau or washout, making the distinction difficult.

BREAST IMAGING: Breast MRI

History

Imaging Findings

Diagnosis

Teaching Points

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