Background/Purpose:  Hydroxychloroquine (HCQ) therapy for autoimmune disease may be associated with detection of curvilinear bodies (CB) on ultrastructural examination of muscle. Whilst ocular toxicity is related to cumulative HCQ dose, the clinical significance of CB is uncertain and whether their detection reflects dose-dependent toxicity is not known.

Methods:  The electronic database of muscle biopsies reported in the Anatomical Pathology Laboratory, SA Pathology was searched from 2006 to the present, to identify biopsies with CB. The clinical features of these patients, including body mass index and cumulative HCQ dose were recorded. A control group of 16 patients with biopsy-proven idiopathic inflammatory myositis (IIM) who were on HCQ at the time of biopsy but who did not have histopathological evidence of CB was identified from the South Australian Myositis Database.

Results:  19 patients with CB on ultrastructural examination of muscle were identified; details were available for 18. Among patients with CB, 7/18 also had IIM. 7/10 of patients with CB who did not have IIM or MHC1/11 expression had documented proximal weakness, 7/11 had raised serum creatinine kinase (CK) levels. There was no difference in body weight (p=0.47), body mass index (p=0.93), cumulative HCQ dose (p=0.52) or cumulative dose adjusted for body weight (p=0.39) or body-mass index (p=0.32) between patients with CB and controls. Patients with CB had lower median CK levels than controls (p=0.034). Weakness was present in 12/17 patients and 12/16 controls (p=1.0). Concurrent proton-pump inhibitors were co-prescribed in 12/18 (67%) patients with CB and in 6/16 (38%) controls (p=0.17).

Conclusion:  In contrast with HCQ-induced ocular toxicity, the development of CB does not appear to be related to cumulative HCQ dose or body weight. Patients with CB frequently have muscle weakness even in the absence of MHC1 expression suggesting a role for non-immune mechanisms of muscle injury. A high proportion of patients with CB are co-prescribed proton pump inhibitors raising the possibility that co-prescription of both agents may disrupt lysosomal function and adversely affect muscle function.

« Back to 2016 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-clinical-significance-of-curvilinear-bodies-on-ultrastructural-examination-of-muscle/