Clinical manifestation, muscular imaging and pathological characteristics of anti-signal recognition particle positive immune-mediated necrotizing myopathy
10.3760/cma.j.cn113694-20240202-00076
- VernacularTitle:抗信号识别颗粒抗体阳性的免疫介导坏死性肌病的临床、肌肉影像及病理特点分析
- Author:
Shiyao LI
1
;
Qianqian QU
;
Xianzhao ZHENG
;
Xiaoli MA
;
Wenhao CUI
;
Dan LI
;
Zheng LYU
;
Jiongbo ZHAO
;
Jiaxuan WANG
;
Cong HU
;
Haidong LYU
Author Information
1. 新乡医学院附属焦作市人民医院神经内科，焦作 454002
- Keywords:
Signal recognition particle;
Immune mediated necrotizing myopathy;
Magnetic resonance imaging;
Muscle pathology
- From:
Chinese Journal of Neurology
2024;57(9):1000-1008
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To analyze the clinical characteristics, muscle imaging and pathological features of patients with anti-signal recognition particle positive immune-mediated necrotizing myopathy (SRP-IMNM).Methods:Nine patients with SRP-IMNM were collected in the Neuromuscular Disease Center of Jiaozuo People′s Hospital from May 2018 to May 2023, who were confirmed by skeletal muscle pathology and myositis-specific autoantibodies detection, and their clinical manifestations, muscle imaging and muscle pathology characteristics were systematically summarized.Results:Among the 9 patients with SRP-IMNM, there were 7 females and 2 males. The age of onset ranged from 18 to 59 years. All the patients presented proximal muscle weakness. Seven patients experienced neck weakness, and dysphagia was present in 5 patients. Laboratory examinations showed elevated serum creatine kinase levels in all 9 patients (1 866-6 725 U/L). Eight patients were combined with other antibodies positivity, except for anti-SRP antibody. Among them, 7 patients were combined with anti-Ro-52 antibody positivity, 4 patients combined with anti-Ro-52 antibody positivity alone, and 3 patients combined with 3 or more positive antibodies simultaneously. Those patients who presented with interstitial lung disease and cardiac involvement were all combined with other antibodies positivity. Seven patients completed thigh muscle magnetic resonance imaging (MRI), which showed diffuse skeletal muscle oedema, partial muscle atrophy and fatty replacement, primarily affecting the posterior thigh muscle group. Two patients underwent shank muscle MRI. The soleus involvement was evident, while the tibialis anterior muscle and gastrocnemius muscles were involved in 1 patient. All 9 patients showed varying degrees of scattered muscle fiber necrosis and regeneration on muscle biopsies. In 1 patient, a small amount of inflammatory cell infiltration was observed. Pipestem capillaries were observed in 4 patients. Immunohistochemical staining revealed a small number of CD68-positive lymphocytes in 8 patients. Additionally, 5 patients showed upregulation of major histocompatibility complex Ⅰ expression on the muscle fiber membrane, while 6 patients showed deposition of membrane attack complex (C5b-9) on non-necrotic muscle fibers and capillaries. P62 staining showed homogeneous fine-granular in sarcoplasm in 6 patients.Conclusions:In addition to proximal muscle weakness, patients with SRP-IMNM often experience neck weakness and dysphagia. Those with multiple antibodies are more likely to develop interstitial lung disease and cardiac involvement. SRP-IMNM patients have diffuse oedema in the affected muscles, and the posterior thigh muscles are more prone to atrophy and fatty tissue formation. C5b-9 deposition and pipestem capillaries are significant pathological features of SRP-IMNM, which provide additional evidence for clinical diagnosis.
