Focal eosinophilic myositis involving the pronator quadratus muscle and flexor tendons in a young woman: A case report

Abstract

Introduction

Idiopathic eosinophilic myositis (IEM) is a poorly understood inflammatory myopathy. We present the case of a patient with this condition who achieved complete symptom resolution following treatment.

Case presentation

A 26-year-old female patient presented with inflammatory changes and pain in the right forearm for 30 days. Physical examination revealed tenosynovitis of the right-hand flexors. Laboratory tests showed eosinophilia and elevated IgE levels. Magnetic resonance imaging (MRI) demonstrated findings consistent with myositis affecting the pronator quadratus muscle and deep finger flexors, along with distal forearm tenosynovitis. A biopsy revealed a lymphoplasmacytic inflammatory infiltrate with abundant eosinophils in both endomysial and perimysial locations. Treatment with deflazacort and antihistamines led to complete symptom resolution.

Conclusions

IEM is an extremely rare disease with heterogeneous clinical manifestations. We hope this case report contributes to a better understanding of this condition and serves as a foundation for future studies on IEM.