The main characteristics of lipomas include a well-circumscribed and encapsulated mass that is usually slow growing.
Intramuscular lipomas arise between the muscle fibres and pass through the intermuscular septa, infiltrating surrounding tissue.
The authors described an unusual case of an intramuscular lipoma of the flexor hallucis brevis muscle as seen in a 54-year-old woman who presented with pain to the medial plantar aspect of the left foot.
On clinical examination, the dorsalis pedis and posterior tibial artery pulses were present; a palpable mass was noted to the medial plantar aspect of the first metatarsal cuneiform joint area.
No pain was elicited with mobilisation of the first ray, with palpation along the course of the posterior tibial tendon, with resisted inversion, or with heel rise.
A mild flexible pes planus deformity was noted.
An MRI of the left foot depicted a well-defined homogenous intramuscular fatty lesion with high signal intensity on T1- and T2- weighted images, without evidence of abnormal enhancement with a postgadolinium T1 fat suppression sequence.
The adipose tissue was composed of uniform adipocytes and contained no atypical stromal cells or lipoblasts; these findings are most consistent with an intramuscular lipoma.
The exact aetiology and pathogenesis of the lipomas remain unclear, with many suggested precipitating factors such as an elevated body mass index, which was observed in the present patient as well.
The authors decided to perform a wide local excision owing to the potential malignant nature of the tumor and the high reported recurrence rates.
There are no set parameters for follow-up once the patient’s surgical site has healed and the benign nature of the tumor has been confirmed.
To date, this patient is walking pain free with no clinical signs of recurrence.
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