Dados do Trabalho

Título

Seropathological correlation in patients with inflammatory myopathy: a cohort study

Resumo

Introduction
Muscle biopsy have been considered the gold standard pattern for the diagnosis of idiopathic inflammatory myopathies (IIM). Myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) have been shown to play an important role in diagnosis and prognosis. We describe a cohort of IIM, correlating histopathological and immunohistochemical with serological findings (MSA and MAA).

Results
Out of 44 patients, 40 tested for MSA or MAA and 38 were underwent muscle biopsy, as the following: 15 (39%) immune-mediated necrotizing myopathy (IMNM), 8 (21%) dermatomyositis (DM), 4 (10.5%) perimysial myopathy (PMM), 3 (7.9%) immune-mediated myopathy (IMM), 2 (5.2%) lipid-storage myopathy (LSM), 5 (13%) other myopathies and 1 (2.6%) inclusion body myositis. A total of 25 cases (62.5%) were seropositive for the following antibodies: 6 (24%) anti-SRP, 5 (20%) antiHMGCR, 3 (12%) anti-Ro52, 2 (8%) anti-Jo1, 2 (8%) anti-Mi2, 2 (8%) anti-Ku, 1 (4%) anti-Jo1 + anti-Ro52, 1 (4%) anti-SRP + anti-Ro52, 1 (4%) anti-SAE1 + anti-Ro52 and 1 (4%) anti-SAE1 + anti-Ro52 + anti-Ku. Among the IMNM, 5 (33.3%) were antiSRP positive (+), 3 (20%) anti-HMGCR+, 1 (6.6%) anti-Ku+, 1 (6.6%) anti-Ro52+ and 1 (6.6%) anti-SRP+ and anti-Ro52+, (sensitivity: 60%). The DM subtypes 1 (12.5%) tested positive for anti-Mi2, 1 (12.5%) anti-SRP, 1 (12.5%) anti-NXP2, 1 (12.5%) anti-SAE1 and anti-Ro52 and 1 (12.5%) anti-SAE1 and anti-Ku + anti-Ro52. Regarding the 4 cases of PMM, 2 (50%) were positive for anti-Jo1 and 1 (25%) for anti-Mi2. Among IMM cases, 1 (33.3%) was positive for anti-Ku and 1 (33.3%) for anti-Jo1 and anti-Ro52. In LSM, 1 (50%) tested positive for anti-HMGCR.

Conclusion
The positive test for MAA and MSA occurred in 62.5% of our sample, demonstrating sensitivity above that reported in the literature (50%). Anti-HMGCR and anti-SRP antibodies were highly specific and sensitive for IMNM, while anti-Jo1 showed a correlation with PMM. On the other hand, anti-Ro52 proved to be the less specific. Lipid accumulation in anti-HMGCR myopathy was probably a secondary finding. The positive case for anti-Mi2 in 1 case of PMM points out to the possibility of DM diagnosis in this subgroup. The presence of MAA in the nonspecific IMM group highlights the value of testing theses autoantibodies in cases only suggestive of a immune process. Overall, the future will decide how important these antibodies are to replace or not the muscle biopsy in IIM.

Palavras Chave

inflammatory myopathy; myositis-associated antibody; myositis-specific antibody; immune-mediated necrotizing myopathy; dermatomyositis; perimisial myopathy