Cutaneous involvement in anti-HMGCR positive necrotizing myopathy.

OBJECTIVE: Anti-3-Hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) positive immune-mediated necrotizing myopathy (IMNM) is a rare disease. It is induced by exogenous substances, most often by statins. Little is known about cutaneous manifestations of HMGCR positive IMNM and about HMGCR antibody positivity in other diseases. METHODS: The characteristics of patients with anti-HMGCR autoantibodies measured at our laboratory between January 2012 and September 2020 were studied. Characteristics of patients with IMNM were compared to those patients with positive antibodies but without muscle involvement. Associations of IMNM with other organ involvements were searched for. RESULTS: Of the 32 patients studied, 23 showed characteristics of IMNM, 9 did not fulfill current classification criteria but most showed signs of connective tissue diseases. Patients with IMNM were older (66 and 35 years, respectively; 0.92 (0.73-0.98); p < 0.001), had more frequent statin exposure (87% and 33%, respectively; 0.84 (0.61-0.94); p = 0.005) and higher mean peak CK (8717U/l and 329U/l, respectively; 1.0 (0.85-1.0); p < 0.001). 13/23 (56%) of IMNM patients showed cutaneous lesions; none of the patients suffered from cancer; only three IMNM patients showed drug-free complete remission. Incidence of IMNM in the catchment area of our center is at least 2.7/Mio/year. CONCLUSION: Cutaneous lesions were found to be more frequent in anti-HMRCR positive IMNM than previously reported. Titer of anti-HMGCR antibodies and CK levels were significantly higher in IMNM than in other autoimmune connective tissue diseases. The data support the hypothesis of an antigen-driven response in IMNM, and suggests an activation of autoreactive B-lymphocytes in non-IMNM patients.

A Rare Case of PL-7-Associated Immune-Mediated Necrotizing Myopathy With Isolated Dysphagia as the Presenting Symptom.

Immune-mediated necrotizing myopathy (IMNM) is a rare, progressive disease that accounts for about 19% of all inflammatory myopathies. Dysphagia occurs in about 20%-30% of IMNM patients. This case results in the third presumptive instance of IMNMwith dysphagia as the initial symptom. Given that isolated dysphagia in IMNM is atypical to the conventional symptoms in the late stage of the disease, it is critical for clinicians to have a high degree of suspicion for IMNM due to the aggressive nature of the disease and its refractoriness to treatment. Additionally, this case also highlights an atypical autoantibody, PL-7, being positive in an IMNM patient who presents with dysphagia as an initial symptom.