A Case of Immune-Mediated Necrotizing Myopathy With Associated Skeletal Muscle Involvement by Sarcoid Granulomata: A Rare Association

Abstract

Abstract Skeletal muscle involvement by noncaseating granulomata occurs in a variety of conditions, including sarcoidosis, infections, and rarely in association with primary inflammatory myopathies such as inclusion body myositis (IBM) and dermatomyositis (DM). Sarcoid myopathy is typically asymptomatic; however, a picture of acute myositis with proximal muscle weakness has been described. Immune-mediated necrotizing myopathy (IMNM) is a subgroup of inflammatory myopathies typically presenting with proximal muscle weakness and markedly elevated muscle enzymes, mostly occurring in the setting of statin treatment. IMNM is associated with positive autoantibodies, but a subset of cases is antibody negative. Here we describe a case of myopathy occurring in association with sarcoidosis with combined features of granulomatous and necrotizing myopathy. The patient was a 54-year-old African American male with medical history significant for statin use 3 years ago, which was discontinued due to myalgia and elevated muscle enzymes and biopsy-proven sarcoidosis diagnosed on a pulmonary lymph node biopsy. He presented with progressive worsening of bilateral proximal weakness involving the upper and lower extremities. Electromyogram showed features of active myopathy with no evidence of peripheral neuropathy. Myositis panel was negative for the following antibodies: anti-Jo1, Mi-2, anti-Ku, PL-7, PL-12, OJ, EJ, and SRP. However, there was elevation of aldolase, CRP, and CK-MB. Biopsy of thigh and deltoid muscle showed necrotic muscle fibers, myophagocytosis with associated minimal inflammation, and multiple well-formed nonnecrotizing granulomas with multinucleated giant cells. Myopathic features include increased internalized nuclei, round atrophic fibers, and scattered split fibers. Specific features of IBM or DM were not present. Conclusion Myopathies developing or worsening after discontinuation of statin are rare. The association of necrotizing myopathy with sarcoidosis is not well described in the literature. Additional studies are warranted to elucidate this association.