Background: Proximal muscle weakness with associated raised creatine kinase (CK) commonly leads to referral to Rheumatology for the investigation of Idiopathic Inflammatory Myopathy (IIM). Some genetic myopathies can have a similar presentation with investigations that suggest inflammatory disease, leading to difficulty with accurate diagnosis (Amato & Brown, 2011; Harlan & Mammen, 2019).

Objectives: To describe the case of a patient with Limb Girdle Muscular Dystrophy Type 2B (LGMD2B), whose initial presentation mimicked an inflammatory myopathy.

Methods: Case report.

Results: A 43-year-old patient was reviewed by Rheumatology due to proximal muscle weakness with a raised CK. Muscle biopsy was suggestive of inflammatory myopathy. Therefore, he was started on treatment with corticosteroids. Corticosteroid treatment resulted in no improvement in his weakness or CK. His diagnosis was reviewed, and he was referred to the Neurology and Genetics services. Following molecular genetic analysis, a diagnosis of Limb Girdle Muscular Dystrophy Type 2B was made.

Conclusion: Muscle biopsies can suggest an inflammatory aetiology in some genetic myopathies (Amato & Brown, 2011; Harlan & Mammen, 2019). If a patient with suspected IIM presents with atypical features, or they do not respond as expected to treatment, then consider a genetic myopathy such as LGMD2B as a cause and involve the Neurology and Genetics services in the case.

REFERENCES:

[1]Amato, A. A., & Brown, R. H., Jr. (2011). Dysferlinopathies. Handb Clin Neurol , 101 , 111-118. https://doi.org/10.1016/b978-0-08-045031-5.00007-4

[2]Harlan, M & Mammen A. L (2019). Myositis Mimics: The Differential Diagnosis of Myositis. In: R. Aggarwal and C. V. Oddis (Eds.) Managing Myositis (pp. 209-223). Springer, Cham.

Disclosure of Interests: None declared