Indian Journal of Rheumatology

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 15  |  Issue : 6  |  Page : 180--186

Is polymyositis a rare or over-diagnosed entity? A descriptive follow-up study of patients initially admitted in a tertiary center with the diagnosis of polymyositis


Pablo Arturo Olivo Pallo, Matheus Santos Rodrigues Silva, Fernando Henrique Carlos de Souza, Samuel Katsuyuki Shinjo 
 Division of Rheumatology, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, SP, Brazil

Correspondence Address:
Dr. Samuel Katsuyuki Shinjo
Division of Rheumatology, Faculdade de Medicina, Laboratorio de Miopatias Inflamatorias, Universidade de Sao Paulo, CEP 01246-903, Cerqueira Cesar, SP
Brazil

Objective: This study aimed to describe a significant sample of patients with an initial diagnosis early-stage polymyositis (PM) in who were reclassified to different diagnoses after new evaluations during follow-ups. Subjects and Methods: In a single-center descriptive study conducted from 2000 to 2019, 108 patients with an initial presumptive diagnosis of PM were admitted to our tertiary center and were reevaluated during follow-up. Patients with promptly suspected or definite initial diagnoses of other autoimmune or hereditary myopathies were excluded. Results: The mean age of the 108 patients when admitted initially into our center was 45.3 ± 15.4 years; they were predominantly female (70.4%) and Caucasian (81.5%). During a median follow-up period of 4.0 years and constant diagnostic reinvestigation, only 30 (27.7%) out of the 108 participants maintained the PM diagnosis, whereas the other patients were re-diagnosed with immune-mediated necrotizing myopathy (20.4%), inclusion body myositis (18.5%), muscular dystrophy 13.0% as (13.0%), antisynthetase syndrome (8.3%), metabolic myopathies (5.6%), and other muscle diseases (7.3%). The initial clinical and laboratory parameters were not distinguishable between the PM and reclassified patients. Twenty-two of 30 patients with PM continued follow-up in our service, all with clinical remission or complete clinical response, full recovery of muscle strength, and normalization of the serum levels for muscle enzymes. Conclusions: Patients with PM should be reevaluated constantly, as PM can mimic other muscle diseases. Notably, only one-third of our large patient samples maintained diagnoses of PM until the end of the present study's data collection.


How to cite this article:
Olivo Pallo PA, Rodrigues Silva MS, de Souza FH, Shinjo SK. Is polymyositis a rare or over-diagnosed entity? A descriptive follow-up study of patients initially admitted in a tertiary center with the diagnosis of polymyositis.Indian J Rheumatol 2020;15:180-186


How to cite this URL:
Olivo Pallo PA, Rodrigues Silva MS, de Souza FH, Shinjo SK. Is polymyositis a rare or over-diagnosed entity? A descriptive follow-up study of patients initially admitted in a tertiary center with the diagnosis of polymyositis. Indian J Rheumatol [serial online] 2020 [cited 2021 Apr 19 ];15:180-186
Available from: https://www.indianjrheumatol.com/article.asp?issn=0973-3698;year=2020;volume=15;issue=6;spage=180;epage=186;aulast=Olivo;type=0