Polymyositis: with interstitial pneumonitis

Case contributed by Dr Hanisalam

Presentation

Proximal muscle weakness in the past 5 months, recent progressive dyspnea. No skin rash.

Patient Data

Age: 70
Gender: Male
Modality: X-ray

Low lung volume with fine peripheral predominantly basal reticulations.

Modality: CT

Bilateral fairly symmetrical predominantly basal inter- and intraloboular septal thickening. Few scattered areas of sub-pleural small cystic changes which could represent early honeycombing of traction bronchiectasis. There is bilateral basal traction bronchiectasis with mild architectural distortion.

The findings could represent early UIP or fibrotic NSIP. No pleural effusion. The pulmonary artery trunk is not dilated to suggest pulmonary arterial hypertension. 

Case Discussion

The thorax is commonly affected in polymyositis or dermatomyositis generally in one or more of three forms: (1) hypo-ventilation and respiratory failure as a result of involvement of respiratory muscles, (2) interstitial pneumonitis, usually with a histologic pattern of UIP or NSIP, (3) aspiration pneumonia secondary to pharyngeal muscle weakness (probably the most common pulmonary complication).

The case demonstrate interstitial pneumonia in the setting of polymyositis (path proven by deltoid muscle biopsy). The pattern is not very specific but we favor fibrotic NSIP over UIP in the absence of definitive honeycombing. Nonetheless, other pattern of interstitial pneumonia has been described in the setting of polymyositis-dermatomyositis including COP and DAD.

Clinically, interstitial lung disease in polymyositis usually present in a manner similar ti acute or subacute community acquired pneumonia. Chest radiographs and CT scans typically demonstrate bilateral irregular linear opacities involving the lung bases. Jo-1 antibody is present in about 38% of patients. There is no significant survival difference between Jo-1 positive or negative groups. Histologically, polymyositis related UIP, NSIP, DAD and organizing pneumonia is similar to their idiopathic counterparts. however, most cases of polymyositis related interstitial lung disease are also associated with mild to moderate pleural fibrosis.

Pulmonary vasculitis and pulmonary hypertension has been reported rarely in patient with dermatomyositis-polymyositis. 

PlayAdd to Share

Case Information

rID: 45584
Case created: 30th May 2016
Last edited: 18th Jul 2016
System: Chest
Inclusion in quiz mode: Included

Updating… Please wait.
Loadinganimation

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.