Sporadic inclusion body myositis: Diagnostic value of p62 immunostaining

Abstract

Background and objectives: Sporadic inclusion body myositis (sIBM) diagnosis is frequently delayed or confused with another class of disorders, and misdiagnosis is common. Sometimes, we have problems diagnosing an sIBM in the early stages or predicting when a PM is going to become an sIBM. In this sense, we believe that p62 immunostaining could help clinicians.

Case report: We report the case of a 61-year-old patient with sIBM who six years earlier had been diagnosed with polymyositis (PM). After muscle biopsies analyses, we showed the natural history of sIBM by p62 expression.

Results: When we looked for p62 aggregates retrospectively we could see small dotted p62 aggregates in the muscle fibres of the first muscle biopsy. Six years later, the patient presented with the typical clinical picture of sIBM, also the muscle biopsy was characteristic, with large p62 aggregates.

Conclusions: Probably p62 immunostaining could help to distinguish PM patients that are going to become sIBM, but to date there has been no systematic study to clarify p62 utility in myositis.

Keywords: Inflammatory myopathies; MCI; Miopatías inflamatorias; Miositis; Myositis; P62; Polimiositis; Polymyositis; sIBM.