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Review
. 2024 Sep;43(3):108-113.
doi: 10.36185/2532-1900-536.

Focal myositis: a literature review of clinical and immunopathological aspects

Alessia Pugliese  1 , Alba Migliorato  2 , Adele Barbaccia  1 , Fiammetta Biasini  1 , Olimpia Musumeci  1 , Antonio Toscano  1 , Carmelo Rodolico  1
Affiliations
Review

Focal myositis: a literature review of clinical and immunopathological aspects

Alessia Pugliese et al. Acta Myol. 2024 Sep.

Abstract

Objectives: Focal myositis (FM) is a rare and restricted skeletal muscle inflammation, presenting as a solid mass with a typical lower leg localization and benign prognosis. In most cases the process solves spontaneously or after immunosuppressant therapy, but sometimes it recurs or progresses to a systemic inflammation. The basis of the disease are mostly unknown.

Methods: Hence, we provide an update of histopathological features of FM, in order to better define the underlying pathomechanisms of this disorder. A PubMed literature search was focused on the case reports published in English from July 1977 to December 2023.

Results: FM and other myositis may show similar morphological features. Emerging studies on MMP molecules and future eventual research on microRNAs (miRNAs) could help in differential diagnosis.

Conclusions: Clinical, laboratory, neurophysiological and imaging findings can allow a correct diagnosis. However, muscle biopsy seems to be the only diagnostic tool to differentiate among FM and other localized soft tissue masses.

Keywords: fibrosis; focal myositis; histopathology; immunohistochemistry; inflammation.

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Conflict of interest statement

All authors declare no conflicts of interest.

Figures

Figure 1.
Figure 1.
Muscle biopsy immunoistochemical images. T-cell CD8+ endomysial infiltrates surrounding muscle fibres in splenius capitis muscle (A) ; scattered macrophages CD68+ in gemellus medialis muscle (B; image from authors’ personal database) (Magnification: 340).
Figure 2.
Figure 2.
MMPs role in differential diagnosis among inflammatory myopathies: absent MMP2 (A) and MMP7 (B) immunoreactivity in FM specimens; MMP9 expression in scattered atrophic muscle fibres (C, arrow) (Magnification: 280) .
See this image and copyright information in PMC

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