Background: Idiopathic inflammatory myopathies (IIM) are heterogenous group of disease which presents with myositis, interstitial lung disease (ILD) and cutaneous manifastations. ILD is a severe involvement and its management can be difficult [1,2]. Patients with IIM have higher morbidity and mortality rates when lung involvement is present [2].

Objectives: Our aim was to describe the clinical characteristics of IIM patients with ILD in a cohort from a single center.
Methods: The medical records of 208 patients who were followed at the rheu- matology clinic between January 2011 and December 2023, and were diag- nosed with IIM were retrospectively evaluated. Among 208 patients, who mets the Bohan and Peter criteria or Conor 2010 criteria were included in the final analyses. Clinical characteristics, laboratory and imaging findings of the patients were recorded. The clinical, laboratory and treatment characteristics of patients with ILD were analyzed.

Results: Table 1 displays the patients’ clinical, imaging, laboratory, and demographic characteristics. We evaluated 109 patients, 78 (71.6%) were female. Only 39 individuals had tests for myositis specific antibodies (MSA), and 94.9% of them had positive results. ILD was seen in 32 of the patients (29.4%). Age at disease onset was higher in ILD patients. Near half of the ILD patients type of myositis was Anti-synthetase Syndrome. Lung involve- ment was more frequent in Ro52 and Jo1 antibody positive patients. Four patients had anti-MDA5 antibody, and one of them died as a result of rapidly progressive interstitial lung disease. There were numerically more patients with malignancy in non-ILD group. The characteristics of patients with lung involvement are shown in Table 2. The most common pattern was non-spe- cific interstitial pneumonia (59.4%) and second was organising pneumonia (18.8%). The pulmonary function tests and diffusing capacity of the lungs for carbon monoxide (DLCO) test were performed in 26 and 21 ILD patients respectively. According to initial steroid dosage and first-line immunosup- pressive treatment, there was no difference between the ILD positive and negative groups.

Conclusion: One of the important involvement of IIM is interstitial lung dis- ease and must be recognized and treated promptly [3,4]. 52 out of 109 patients in our study had an antibody result that was specific or associated with myositis

Although our patients with lung involvement had milder muscle involvement, their CRP levels were higher and most of them have an MSA. Sometimes it is difficult to diagnose patient with IIM if muscle or skin involvement of the patients not prominent. In such patients, MSA or MAA tests become even more impor- tant. It might be challenging to diagnose and manage IIM with ILD involvement, thus it is essential to adequately analyze the patient and risk factors [5].