DM/PM associated ILD

Q: 54 years old female with an established diagnosis of dermatomyositis (DM) is admitted to ICU with community-acquired pneumonia which quickly developed into impending respiratory failure, and required intubation. There is a high concern for interstitial lung disease (ILD). Which of the following finding will favor the diagnosis of ILD? (select one)

A) eosinophilia

B) positive anti-Jo-1 antibody

C) restrictive pattern on PFT

D) a disproportionately low DLCO

Answer: B

Patients with known history of dermatomyositis (DM) or polymyositis (PM), have a very high risk of developing ILD. Said that it is not easy to make the diagnosis as these patients are usually on medications that can cause drug-induced pneumonitis, or respiratory muscle weakness causing dyspnea, or pulmonary hypertension. 

Although high resolution CT scan (HRCT) is essential to make the diagnosis but it should be read with other laboratory tests, as patient might have various other conditions combined.

• Peripheral blood eosinophilia favors drug-induced pneumonitis (choice A).
• Positive anti-Jo-1 is almost certain to establish the diagnosis of DM/PM-associated ILD (choice B).
• PFT with proportionately more restriction than gas transfer abnormality suggests respiratory muscle weakness (choice C).
• disproportionately low DLCO relative to lung volume suggests pulmonary hypertension (choice D).

#pulmonary

#rheumatology

References:

1. Marie I, Josse S, Hatron PY, Dominique S, Hachulla E, Janvresse A, Cherin P, Mouthon L, Vittecoq O, Menard JF, Jouen F. Interstitial lung disease in anti-Jo-1 patients with antisynthetase syndrome. Arthritis Care Res (Hoboken). 2013 May;65(5):800-8. doi: 10.1002/acr.21895. PMID: 23203765.

2. Leu CC, Lan JL. Anti-Jo-1 antibody in patients with polymyositis/dermatomyositis. Zhonghua Min Guo Wei Sheng Wu Ji Mian Yi Xue Za Zhi. 1992 Feb;25(1):41-7. PMID: 1306148.

3. Monti S, Montecucco C, Cavagna L. Clinical spectrum of anti-Jo-1-associated disease. Curr Opin Rheumatol. 2017 Nov;29(6):612-617. doi: 10.1097/BOR.0000000000000434. PMID: 28796005.