Concurrent positive anti-3-hydroxy-3-methylglutaryl-coenzyme a reductase antibody with reducing body myopathy: Possible double trouble

Systemic sclerosis associated myopathy: how to treat

Purpose of review

Systemic sclerosis (SSc) and myositis are two different entities that may coexist as an overlap syndrome. Immunological biomarkers such as anti-PM/Scl or anti-Ku reinforce the syndrome. This review is focused on the treatment of different and characteristic manifestations of this syndrome.

Recent findings

Among the different phenotypes of muscle involvement in patients with SSc, the fibrotic pattern and the sporadic inclusion body myositis must be identified early to avoid a futile immunosuppressive treatment. Other forms such as dermatomyositis, non-specific myositis and immune-mediated necrotizing myopathy need to receive conventional immunosuppressive therapy considering that high dose of glucocorticoids may induce a scleroderma renal crisis in patients with SSc. Physicians must be aware of the existence of a "double trouble" association of hereditary myopathy with an autoimmune phenomenon. Several autoantibodies, mainly anti-PM/Scl and anti-Ku may help to define specific phenotypes with characteristic clinical manifestations that need a more specific therapy. Vasculopathy is one of the underlying mechanisms that link SSc and myositis. Recent advances in this topic are reviewed.

Summary

Current treatment of SSc associated myopathy must be tailored to specific organs involved. Identifying the specific clinical, pathological, and immunological phenotypes may help to take the correct therapeutic decisions.

Inherited myopathy plus: Double-trouble from rare neuromuscular disorders

A rare disorder in the USA is one that affects <200,000 people, making inherited myopathies rare diseases. Increasing access to genetic testing has been instrumental for the diagnosis of inherited myopathies. Genetic findings, however, require clinical correlation due to variable phenotype, polygenic etiology of certain inherited disorders, and possible co-existing independent neuromuscular disorders. We searched the Mayo Clinic Rochester medical record (2004-2020) to identify adult patients carrying pathogenic variants or likely pathogenic variants in genes causative of myopathies and having a coexisting independent neuromuscular disorder classified as rare at https://rarediseases.info.nih.gov/. One additional patient was identified at Nationwide Children's hospital. Clinical and laboratory findings were reviewed. We identified 14 patients from 13 families fulfilling search criteria. Seven patients had a "double-trouble" inherited myopathy; two had an inherited myopathy with coexistent idiopathic myositis; three had an inherited myopathy with coexisting rare neuromuscular disorder of neurogenic type; a female DMD carrier had co-existing distal spinal muscular atrophy, which was featuring the clinical phenotype; and a patient with a MYH7 pathogenic variant had Sandhoff disease causing motor neuron disease. These cases highlight the relevance of correlating genetic findings, even when diagnostic, with clinical features, to allow precise diagnosis, optimal care, and accurate prognosis.

Case report: Diagnostic clues for anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase myopathy in pediatric patients

Introduction

Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) myopathy is a recently recognized pathology, but appears less common in children and the characteristics of pediatric cases remain unclear.

Case report

We report a pediatric case of anti-HMGCR myopathy accompanied by skin rash. Motor function and serum creatine kinase level normalized after combinational treatment including early intravenous immunoglobulin, methotrexate, and corticosteroid.

Literature review

We searched PubMed and identified reports with detailed clinical information of 33 pediatric patients <18 years old with anti-HMGCR myopathy. Among these 33 patients and our own case, skin rash and maximum serum creatine kinase level >5,000 IU/L were observed in 44% (15 patients) and 94% (32 patients), respectively. Skin rash was present in 15 of the 22 patients (68%) ≥7 years old and none of the 12 patients (0%) <7 years old. Among the 15 patients with skin rash, 12 (80%) presented with erythematous rash.

Conclusion

Erythematous skin rash may offer a clue to the diagnosis of anti-HMGCR myopathy in children with muscle weakness and serum creatine kinase level >5,000 IU/L in the absence of other myositis-specific antibodies, particularly in patients ≥7 years old. Our results suggest the importance of early anti-HMGCR testing in pediatric patients with these manifestations.

A Child with Refractory and Relapsing Anti-3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Myopathy: Case-Based Review

BACKGROUND/OBJECTIVE

Anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) myopathy is rare in children. Here, we present a boy with relapsing refractory anti-HMGCR myopathy along with a systematic literature review.

CASE REPORT

17-year-old boy with five years of muscle weakness, rash, high creatinine kinase (CK) levels, and muscle biopsy compatible with inflammatory myopathy was diagnosed with juvenile dermatomyositis. He was treated with corticosteroids, intravenous immunoglobulin (IVIG), and methotrexate. His muscle weakness improved with this treatment although never completely resolved. CK levels decreased from ∼15000 U/L to ∼3000 U/L. At the age of 15, muscle weakness relapsed after an upper respiratory tract infection; pulse corticosteroid treatment was administered. The re-evaluated muscle biopsy showed a necrotizing pattern and the HMGCR antibody was positive confirming anti-HMGCR myopathy when he was 16. The diagnostic delay was 50 months. Disease activity was monitored by Medical Research Council score, MRI and functional tests. Despite corticosteroids, methotrexate, IVIG, cyclosporine A, and rituximab therapies, muscle weakness improved only slightly during the first three months and remained stable afterwards.Results of the Literature Search:We identified 16 articles describing 50 children (76% female) with anti-HMGCR myopathy by reviewing the English literature up to March 1st, 2022. Proximal muscle weakness was the most common clinical symptom (70.8%). Corticosteroids (84.8%), IVIG (58.7%), and methotrexate (56.5%) were preferred in most cases. Complete remission was achieved in nine patients (28.1%).

CONCLUSION

Diagnosis and management of children with anti-HMGCR myopathy are challenging. Complete remission is achieved in only one third of these patients. Imaging biomarkers may aid treatment.

Pediatric immune-mediated necrotizing myopathy

Immune-mediated necrotizing myopathy (IMNM) is a type of inflammatory myopathy. Most patients with IMNM produce anti-3-hydroxy-3-methylglutaryl coenzyme A reductase or anti-signal-recognition particle autoantibodies. IMNM is much rarer in children than in adults. We conducted this mini review focusing on pediatric IMNM to present current evidence regarding its epidemiology, clinical characteristics, diagnosis, and treatment. Our findings indicate that pediatric IMNM often causes severe muscle weakness and is refractory to corticosteroids alone. Furthermore, delayed diagnosis is common because of the clinicopathological similarity between IMNM and inherited myopathy. Raising awareness regarding pediatric IMNM may facilitate early diagnosis and effective treatment.

Becker Muscular Dystrophy Accompanied by Anti-HMGCR Antibody-positive Immune-mediated Necrotizing Myopathy

Becker muscular dystrophy (BMD) is an X-linked neuromuscular disease characterized by progressive muscle weakness that currently has no cure. Immune-mediated necrotizing myopathy (IMNM) is a type of autoimmune inflammatory myopathy characterized by proximal muscle weakness that is treated with immunosuppressive therapy. We herein report a patient diagnosed with BMD complicated with IMNM by a pathological analysis. Notably, the patient had an elevated serum anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody level. Oral glucocorticoid and methotrexate treatment partially improved the muscle weakness with decreased levels of serum creatine kinase. An accurate diagnosis is important for therapeutic decisions in these complicated cases.

Clinical and pathological features of immune-mediated necrotising myopathies in a single-centre muscle biopsy cohort

Objective

Immune-mediated necrotising myopathy (IMNM) is a subset of idiopathic inflammatory myopathies (IIM) characterized by significantly elevated creatine kinase level, muscle weakness and predominant muscle fibre necrosis in muscle biopsy. This study aimed to investigate the clinical and pathological characteristics of patients with IMNM in a single-centre muscle biopsy cohort.

Methods

A total of 860 patients who had muscle biopsy reports in our centre from May 2008 to December 2017 were enrolled in this study. IMNM was diagnosed according to the 2018 European Neuromuscular Centre (ENMC) clinicopathological diagnostic criteria for IMNM.

Results

The muscle biopsy cohort consisted of 531 patients with IIM (61.7%), 253 patients with non-IIM (29.4%), and 76 undiagnosed patients (8.8%). IIM cases were classified as IMNM (68[7.9%]), dermatomyositis (346[40.2%]), anti-synthetase syndrome (82[9.5%]), polymyositis (32[3.7%]), and sporadic inclusion body myositis (3[0.3%]). Limb girdle muscular dystrophy (LGMD) 2B and lipid storage myopathy (LSM) are the two most common non-IIM disorders in our muscle biopsy cohort. IMNM patients had a higher onset age (41.57 ± 14.45 vs 21.66 ± 7.86 and 24.56 ± 10.78, p < .0001), shorter duration (21.79 ± 26.01 vs 66.69 ± 67.67 and 24.56 ± 10.78, p < .0001), and more frequent dysphagia (35.3% vs. 3.4 and 6.3%, p = .001) than LGMD 2B and LSM patients. Muscle biopsy from IMNM showed more frequent muscle fibre necrosis (95.6% vs 72.4 and 56.3%, p < .0001), overexpression of major histocompatibility complex-I on sarcolemma (83.8% vs 37.9 and 12.9%, p < .0001), and CD4⁺ T cell endomysia infiltration (89.7% vs 53.6 and 50%, p < .0001) compared with those from LGMD 2B and LSM patients.

Conclusions

It is easy to distinguish IMNM from other IIM subtypes according to clinical symptoms and myositis specific antibodies profiles. However, distinguishing IMNM from disorders clinically similar to non-IIM needs combined clinical, serological and pathological features.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05372-z.

Autoantibodies against Four-and-a-Half-LIM Domain 1 (FHL1) in Inflammatory Myopathies: Results from an Australian Single-Center Cohort

Objectives

To determine the prevalence and associations of autoantibodies targeting a muscle-specific autoantigen, four-and-a-half-LIM-domain 1 (FHL1), in South Australian patients with histologically-confirmed idiopathic inflammatory myopathies (IIM) and in patients with SSc.

Material and methods

Sera from patients with IIM (n = 267) from the South Australian Myositis Database (SAMD), SSc (n = 174) from the Australian Scleroderma Cohort Study (ASCS) and healthy controls (HC, n = 100) were analysed for anti-FHL1 autoantibodies by Enzyme-Linked ImmunoSorbent Assay (ELISA).

Results

Autoantibodies to FHL1 were more frequent in patients with IIM (37/267, 13.8%) compared with SSc (12/174, 7%) (P < 0.02) and HC (2/100, 2%) (P < 0.001). The most common IIM subtypes among FHL1⁺ IIM patients were (32%) and IBM (2/37, 32%). No statistically significant differences in muscular or extra-muscular manifestations of IIM were found when comparing patients who were anti-FHL1⁺ with their anti-FHL1^– counterparts. In 29/37 (78%) anti-FHL1⁺ patients, no myositis-specific autoantibodies (MSA) were present. In FHL1⁺ muscle biopsies, there was less frequent infiltration by CD45⁺ cells (P = 0.04). There was a trend for HLA alleles DRB1*07 and DRB1*15 to be more frequent in anti-FHL1⁺ compared with anti-FHL1^– patients (9/25 vs 19/113, P = 0.09 and 8/25 vs 15/114, P = 0.09, respectively).

Conclusions

We report a substantial prevalence (13.8%) of anti-FHL1 autoantibodies in a large cohort of patients with histologically confirmed IIM; 75% of these cases did not have a detectable myositis-specific autoantibody. Anti-FHL1 autoantibodies were also detected in a subgroup of patients with SSc (7%), indicating that anti-FHL1 autoantibodies may not be myositis-specific. The trend towards an HLA-DR association might indicate a specific immune response to the FHL1 protein.

Reducing body myopathy associated with the LIM2 p.(His123Arg) FHL1 variant

Reducing body myopathy (RBM) is a rare muscle disorder, with marked presence of characteristic intracytoplasmic aggregates in affected muscle fibers. RBM is associated with FHL1 gene mutations. Clinical presentations of RBM have ranged from early fatal to adult onset progressive muscle weakness. We present herein the clinical, electrodiagnostic, and muscle biopsy findings of a 17-year-old female with progressive muscle weakness and contracture. Muscle biopsy showed atrophic fibers that contained menadione nitroblue tetrazolium (NBT) positive reducing bodies. Genetic testing revealed a variant of uncertain significance in the FHL1 gene at a position known to be pathogenic when substituted by other amino acids (p.His123Arg). This variant was later reclassified as pathogenic.

Juvenile idiopathic inflammatory myopathies with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibodies in a Chinese cohort

AIMS

To characterize the clinical and histopathological characteristics and treatment outcomes of juvenile idiopathic inflammatory myopathies (JIIMs) with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibodies in a Chinese cohort.

METHODS

We detected anti-HMGCR antibodies in a series of Chinese JIIM by ELISA and indirect immunofluorescence assay on HEK293 cells, and summarized the clinical findings of these anti-HMGCR antibody-positive patients.

RESULTS

Of 32 JIIM patients, 5 (15.63%) were found to be anti-HMGCR antibody-positive. The disease duration was 1.20 ± 0.45 months. Statin exposure was not found. Four patients had skin lesions, while typical pathological features of dermatomyositis such as perifascicular atrophy or myxovirus resistance protein A expression were not found. The mean creatine kinase level was 16771.60 U/L. Among the four patients who received long-term (10.46 ± 1.42 years) follow-up, three exhibited favorable outcomes with prednisone and additional immunosuppressants.

CONCLUSIONS

Our study indicates that anti-HMGCR antibodies may not be rare in Chinese JIIM. These anti-HMGCR-positive JIIMs were characterized by acute onset, substantially elevated creatine kinase level, and skin lesions without perifascicular changes in muscle pathology. The treatment outcome is generally favorable with the combination of steroid and immunosuppressant.

Spontaneous symptomatic improvement in a pediatric patient with anti-3-hydroxy-3-methylglutraryl-coenzyme A reductase myopathy

Immune-mediated necrotizing myopathy with antibodies against 3-hydroxy-3-methylglutaryl-coenzyme A reductase is a subgroup of idiopathic inflammatory myopathies mainly described in adults and requiring long term immunomodulatory therapy for remission. Pediatric patients have been reported as small series or sporadic cases. We report an eight-year-old girl with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase myopathy, presenting with subacute proximal limb weakness, high creatine kinase and a muscle biopsy displaying necrotizing pattern, initially diagnosed as limb-girdle muscular dystrophy, but subsequently negative genetic testing. A noteworthy spontaneous improvement in her weakness suggested the possibility of an acquired autoimmune myopathy, confirmed by positive testing of anti-HMGCR antibodies titers. After four years of follow-up, she maintains normal strength with high levels of anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody. This patient shows that spontaneous fluctuations and spontaneous long-lasting symptomatic remission can occur in patients with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase myopathy. Some patients could present a wane and wax clinical course, an important aspect when assessing response to therapy.