Analysis of clinical and pathological characteristics of scleromyositis patients with positive anti⁃Ku or anti⁃PM⁃Scl antibodies

Abstract

Objective To summarize the clinical manifestations and histopathological characteristics of skeletal muscle in scleromyositis patients with positive anti‑Ku or anti‑PM‑Scl antibodies. Methods and Results Retrospective collection of clinical data from 70 scleromyositis patients diagnosed at Peking University First Hospital from January 2010 to March 2023, analysis showed the average onset age of patients was 36.00 (20.75, 51.25) years old. The initial symptoms of 77.14% (54/70) patients was mainly in the proximal limbs myasthenia [74.29% (52/70)], mild to moderate [77.14% (54/70)], and 52.86% (37/70) patients had systemic symptoms such as fatigue or skin involvement during the course of the disease. The serum creatine kinase (CK) level was 2775.00 (995.50, 4995.75) U/L. About 32.86% (23/70) were positive for anti‑Ku antibody, 65.71% (46/70) were positive for anti‑PM‑Scl antibody, 1.43% (1/70) were both positive, and 27.14% (19/70) could also had increased level of other myositis antibodies. The main histopathological changes were inflammatory [41.43% (29/70)] or necrotic [24.29% (17/70)] myopathic pathological changes, presenting as muscle fiber atrophy [91.43% (64/70)], necrosis [68.57% (48/70)] or regeneration [85.71% (60/70)]. Comparison of symptoms, signs and histopathological characteristics of skeletal muscle between patients with positive anti‑Ku antibody and with positive anti‑PM ‑Scl antibody, female proportion (χ2 = 4.381, P = 0.036) and C5b9 deposition damage (χ2 = 4.725, P = 0.030) were higher in the former than those in the latter. Conclusions Scleromyositis patients with positive anti‑Ku or anti‑PM‑Scl antibodies mostly started in young and middle age, mainly manifesting as mild to moderate myasthenia in the proximal limbs, and skeletal muscle inflammatory or necrotic myopathic lesions as characteristic pathological changes. Compared with positive anti ‑ PM ‑ Scl antibody patients, positive anti ‑ Ku antibody scleromyositis patients were mainly female, and skeletal muscle complement deposition was more notable.

DOI: 10.3969/j.issn.1672⁃6731.2023.09.004