Surgical resection of a giant intramuscular lipoma of the biceps brachii: a case report and review of the literature

PIK3CA mutation testing as a valuable molecular surrogate for lipomatosis of the median nerve: clinicopathological and molecular analysis of six cases

Lipomatosis of peripheral nerves (LPN, also known as fibrolipomatous or lipofibromatous hamartoma of peripheral nerves) is a very rare, benign, intraneural, tumorous lesion that predominantly involves the median nerve but may rarely affect any peripheral nerve. Recently, PIK3CA mutations have been reported in macrodactyly, a rare condition related to LPN, and in other localized lipomatous overgrowth syndromes. In this retrospective study, we report 6 cases of FPN involving the median nerve (4 of them identified among 570 patients with carpal tunnel syndrome who underwent surgical decompression at our center from 2012 to 2022 and two seen in consultation by one of the authors). All cases were diagnosed via biopsy or resection supplemented by MRI. Patients were 4 males and 2 females aged 23 to 60 years (mean 38 years). One patient with bilateral lesions had in addition extensive angiomatosis of the paravertebral region. Histological examination showed an abnormal amount of mature fatty tissue containing disordered fibrous bands, entrapping normal-looking nerve fibers with prominent perineurial and endoneurial fibrosis. Genetic analysis using snapshot assay constructed to detect hotspots mutations in PIK3CA revealed similar PIK3CA mutations (p.H1047R; c.3140A>G) in 5/6 cases (83.3%). Our study represents a further contribution to the literature on LPN and highlights the diagnostic value of PIK3CA mutation testing as surrogate tool in equivocal cases and in those lesions without associated macrodactyly, especially as the biopsy findings of this lesion are essentially nonspecific.

Endoscopically Assisted Resection of Intramuscular Lipoma of the Soleus

Intramuscular lipoma is a rare soft-tissue tumor with an overall incidence of less than 1% of all lipomas. It primarily occurs in the trunk and proximal parts of the upper and lower extremities. Intramuscular lipoma of the soleus muscle has not been reported before in the English literature and the best treatment option is not known. The purpose of this Technical Note is to describe the details of endoscopically assisted resection of intramuscular lipoma of the soleus. This is indicated for well demarcated intramuscular lipoma of the soleus and is contraindicated in infiltrating intramuscular lipoma. Besides the advantage of minimally invasive surgery, this endoscopic technique allows en bloc resection of the intramuscular lipoma.