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

Osterloh J, Agaimy A, Fried F, Stöhr R, Janka RM, Arkudas A, Horch RE (2023)

Publication Type: Journal article

Publication year: 2023

Journal

Virchows Archiv Springer Verlag (Germany)

Abstract

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.

Authors with CRIS profile

Justus Osterloh Department of Plastic and Hand Surgery Abbas Agaimy Lehrstuhl für Allgemeine Pathologie und Pathologische Anatomie Robert Stöhr Lehrstuhl für Allgemeine Pathologie und Pathologische Anatomie Rolf Matthias Janka Institute of Radiology Andreas Arkudas Medizinische Fakultät Raymund Horch Professur für Plastische Chirurgie und Handchirurgie

How to cite

APA:

Osterloh, J., Agaimy, A., Fried, F., Stöhr, R., Janka, R.M., Arkudas, A., & Horch, R.E. (2023). PIK3CA mutation testing as a valuable molecular surrogate for lipomatosis of the median nerve: clinicopathological and molecular analysis of six cases. Virchows Archiv. https://doi.org/10.1007/s00428-023-03540-7

MLA:

Osterloh, Justus, et al. "PIK3CA mutation testing as a valuable molecular surrogate for lipomatosis of the median nerve: clinicopathological and molecular analysis of six cases." Virchows Archiv (2023).

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