Intramuscular lipoma of deltoid

Case contributed by Nafisa Shakir Batta
Diagnosis almost certain

Presentation

Patient complaints of pain and restricted movements of shoulder in internal rotation and overhead abduction.

Patient Data

Age: 45 years
Gender: Female

Extended MRI study of shoulder joint showed a well defined oblong lipomatous lesion underneath the deep fascia, insinuating, splaying and extending under the anterior fibers of deltoideus muscle. This fatty SOL was seen to extend craniocaudally from the level of humeral head upto 4cm prior to the insertional deltoid tuberosity at midshaft of humerus .

These findings are compatible with subdeltoid intramuscular lipoma.

Case Discussion

Lipomas are common benign soft tissue tumors, well capsulated, mostly resectable and occuring practically anywhere. Lipomas account for almost 50%of all soft tissue tumors and affect 1% of the general population, incidence peak being 40-60 years. They are classfied as many histological types based on various lipomatous tissue subtypes. They may be grossly classified by location, ie, superficial and deep lipomas. Deep lipomas may be intramuscular or intermuscular.

Intramuscular lipoma is an unusual and rare entity. They can be well circumscribed or infiltrative.

What is even more unsusual is the patients presentation, in this case, she presented with restricted abduction at shoulder, also on internal rotation and flexion, there was a well defined bulge at the anterior soft tissues which disappeared on neutral positioning : typically attributable to the flexion of the anterior fibers of deltoid underlying which the lipoma was seated.

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