Extra-abdominal desmoid fibromatosis

Case contributed by Fabian Boeckel


Swelling of the right upper arm with a slow increase in volume first noticed one year ago.

Patient Data

Age: 55
Gender: Female

The ROI is marked by a capsule stuck to the skin.

In the middle of the right upper arm in the subfascial space is an irregularly contoured structure with streaky extensions into the surrounding muscles and into the epifascial fat.

The signal is equal to muscular intensity in native T1 weighted series and with thoroughly high intensity in T1 C+. Just a lightly elevated signal in T2 weighted images and with high intensity in the PD weighted series.

Case Discussion


Parts of a fibroblastic spindle cell lesion without significant cellular atypia. In immunohistochemistry, strong nuclear staining for b-catenin in the majority of spindle cells with partial positivity for desmin and SMA.

In the PCR analysis of the CTNNB1 gene (Exon 3) detection of a point mutation (c.121A>G; p.T41A).


Extra-abdominal desmoid fibromatosis.

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Case information

rID: 63617
Published: 15th Oct 2018
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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