Chronic Lymphocytic Thyroiditis and Aggressiveness of Pediatric Differentiated Thyroid Cancer.

OBJECTIVES/HYPOTHESIS: Hashimoto's Thyroiditis (HT) is a common cause of hypothyroidism. Among adults with differentiated thyroid cancer (DTC), HT appears to be associated with less severe disease burden. In the absence of information regarding HT and disease burden among children with DTC, we assessed the relationship between pediatric DTC severity and HT. STUDY DESIGN: Retrospective cohort. METHODS: Charts from 90 pediatric patients who underwent surgical removal of DTC from 2002 to 2017 at tertiary-care children's hospital were reviewed. Demographic, clinical, surgical, pathology, and outcome details were compared between patients with and without HT. Consistency among diagnostic modalities of HT was also evaluated. RESULTS: Median age at presentation was 16.0 years (range 4.2-18.9 years). Twenty-two patients were male (24%). Forty-five patients (50%) had HT based on presence of thyroid autoantibodies and/or surgical pathology findings and 45 patients did not have HT. Patients with HT had increased odds of microcalcifications (odds ratio [OR]: 3.01, P = .031) and decreased odds of palpable nodules (OR: 0.212, P = .024) and T2 lesions (vs. T1) (OR: 0.261, P = .015) compared with non-HT. No significant differences in demographics and the incidence of multifocality, extrathyroidal extension, lymphovascular invasion, lymph node or pulmonary metastases, disease recurrence, or radioactive iodine treatment were found between the two groups. Thyroglobulin/thyroid peroxidase autoantibodies and surgical pathology indicative of HT were concordant in 82.4% (κ = 0.635, P < .001). CONCLUSION: HT was present in 50% of children with DTC. Patients with DTC and HT presented with smaller tumors compared to non-HT patients. No significant differences in other markers of disease aggressiveness were found between the two groups. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:1668-1674, 2022.

Myositis Autoantigen Expression Correlates With Muscle Regeneration but Not Autoantibody Specificity.

OBJECTIVE: Although more than a dozen myositis-specific autoantibodies (MSAs) have been identified, most patients with myositis are positive for a single MSA. The specific overexpression of a given myositis autoantigen in myositis muscle has been proposed as initiating and/or propagating autoimmunity against that particular autoantigen. The present study was undertaken to test this hypothesis. METHODS: In order to quantify autoantigen RNA expression, RNA sequencing was performed on muscle biopsy samples from control subjects, MSA-positive patients with myositis, regenerating mouse muscles, and cultured human muscle cells. RESULTS: Muscle biopsy samples were available from 20 control subjects and 106 patients with autoantibodies recognizing hydroxymethylglutaryl-coenzyme A reductase (n = 40), signal recognition particles (n = 9), Jo-1 (n = 18), nuclear matrix protein 2 (n = 12), Mi-2 (n = 11), transcription intermediary factor 1γ (n = 11), or melanoma differentiation-associated protein 5 (n = 5). The increased expression of a given autoantigen in myositis muscle was not associated with autoantibodies recognizing that autoantigen (all q > 0.05). In biopsy specimens from both myositis muscle and regenerating mouse muscles, autoantigen expression correlated directly with the expression of muscle regeneration markers and correlated inversely with the expression of genes encoding mature muscle proteins. Myositis autoantigens were also expressed at high levels in cultured human muscle cells. CONCLUSION: Most myositis autoantigens are highly expressed during muscle regeneration, which may relate to the propagation of autoimmunity. However, factors other than overexpression of specific autoantigens are likely to govern the development of unique autoantibodies in individual patients with myositis.

Anti-NT5C1A autoantibodies are associated with more severe disease in patients with juvenile myositis.

OBJECTIVES: Autoantibodies recognising cytosolic 5'-nucleotidase 1A (NT5C1A) are found in adult patients with myositis and other autoimmune diseases. They are especially prevalent in adults with inclusion body myositis (IBM), in which they are associated with more severe weakness and higher mortality. This study was undertaken to define the prevalence and clinical features associated with anti-NT5C1A autoantibodies in juvenile myositis. METHODS: We screened sera from 380 patients with juvenile myositis, 30 patients with juvenile idiopathic arthritis (JIA) and 92 healthy control children for anti-NT5C1A autoantibodies. Clinical characteristics were compared between patients with myositis with and without anti-NT5C1A autoantibodies. RESULTS: Anti-NT5C1A autoantibodies were present in 102 of 380 (27%) patients with juvenile myositis and in 11 of 92 (12%) healthy control children (P=0.002) and 27% of children with JIA (P=0.05 vs controls). Sera of 83 of 307 (27%) patients with juvenile dermatomyositis and 16 of 46 (35%) patients with juvenile overlap myositis were anti-NT5C1A autoantibody-positive (P<0.01 vs healthy controls for each), but sera of only 3 of 27 (11%) patients with juvenile polymyositis were anti-NT5C1A-positive. Patients with juvenile myositis with and without anti-NT5C1A autoantibodies had similar clinical phenotypes. However, patients with anti-NT5C1A autoantibody-positive myositis had greater pulmonary symptoms at diagnosis (P=0.005), more frequent hospitalisations (P=0.01) and required a larger number of medications (P<0.001). CONCLUSION: Anti-NT5C1A autoantibodies are present in more than one-quarter of children with juvenile myositis and JIA compared with only 12% of healthy children, suggesting they are myositis-associated in children. As in adults with IBM, patients with juvenile myositis with anti-NT5C1A autoantibodies have more severe disease.