We introduce two patients who share the common diagnosis of axillary musculoskeletal fibromatosis. We explore the initial presentation, circumstances leading to diagnosis, imaging characteristics and treatment options. Desmoid tumours are rare indolent proliferative masses which may initially appear as aggressive lesions. Multisequential MRI imaging plays a vital role in diagnosis. There is no current accepted clinical guideline for treatment [1, 6]. Patient One: A 33-year-old female was referred to the orthopaedic outpatient clinic after gradually increasing left shoulder pain, reduced strength, and function over 10...

Desmoid type fibromatosis or desmoid tumours are rare neoplasms classified by the World Health Organization as an intermediate lesion that is locally aggressive[1]. It is a non-metastasizing, monoclonal fibroblastic proliferative disease[2]. Desmoid tumours usually occur in the abdomen but are rarely seen in the axillae where their relationship to surrounding neurovascular structures including the brachial plexus can cause significant morbidity, posing a challenge to surgeons[3]. The cause of desmoid tumours remains unknown and most desmoid tumours occur sporadically. Desmoid tumours constitute 0.03% of all neoplasms...

The use of imaging in desmoid tumours can define the extension and potential for surgical excision of the lesion. MRI is the preferred modality for interval imaging for axillary musculoskeletal fibromatosis [9]. T1-weighted images of desmoid tumours are commonly hypointense (due to high cellullarity) or isointense to muscle whereas on T2-weighted images they are hyperintense. The use of gadolinium contrast shows moderate enhancement with hypointense bands due to collagen bundles which can increase the specificity of the diagnosis [10]. The mean ADC of desmoid tumours...

There are no clear treatment guidelines due to the rarity of desmoid tumors, this is a potential avenue for further developing research in skeletal radiology. MRI is an invaluable tool during the diagnosis, pre-treatment planning and follow up of desmoid tumours as it can determine the extent of infiltration and the relationship of surrounding structures. These findings can have important implications in the treatment that is offered to the patient [6].

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