Intramuscular Lipoma of the Pectoralis Major Simulating a Breast Lump

Intramuscular lipoma is a deep-seated lipoma that arises in the muscle and is benign and relatively rare. Intramuscular lipomas of the pectoralis major muscle have been reported to mimic malignant breast tumours. Here, we present a 69-year-old female presenting with painless lump in right breast of three months duration progressively increasing in size. Examination revealed a soft, lobulated lump which was freely mobile with no fixity to surrounding structures. Mammogram revealed large radiopaque lesion noted in the retro glandular region with lucent linear striation in the centre. Correlated sonomammography showed a large hyperechoic lesion in retromammary region, anterior to the pectoralis major muscle. On Doppler study there was no vascularity, an ultrasound guided FNAC was done which showed adult adipocytes, suggestive of a lipoma. On exploration, a large encapsulated intramuscular lipoma of the pectoralis major was noted and excised, final histopathological examination also confirmed the diagnosis of lipoma. Lipoma can be considered as a rare differential diagnosis for breast lump.