Tuesday, May 30, 2017

Pulmonary manifestations of connective tissue diseases

This post is drawn from a BMJ review which is one of the best I've seen on the topic. Though titled Management of interstitial lung disease associated with connective tissue disease it covers both treatment and diagnosis of the entire spectrum of pulmonary manifestations. Some key points are discussed below.

Systemic sclerosis

Interstitial lung disease (ILD) exists in most patients at some point in the course with a wide spectrum of severity. Pulmonary hypertension (PH) is common but less so. ILD tends to associate more with the diffuse form of SScl and PH with the limited form but the associations are not exclusive and both can occur at the same time. Nonspecific interstitial pnuemonitis (NSIP) is the most common histologic pattern but usual interstitial pneumonitis (UIP) is seen in 10-20%. Though steroids are commonly used as initial treatment across the spectrum of CTD associated ILD of a variety of causes, caution is in order with SScl due to the association of steroid use with an increased risk of renal crisis. Dosage limitations apply. Pleural involvement is unusual.

Rheumatoid arthritis

ILD is common with UIP in half or more. Airway and pleural disease are common. PH is unusual.

Sjogren's syndrome

ILD is less common than in many other rheumatic diseases but does sometimes occur in the form of NSIP and lymphocytic interstitial pneumonitis (LIP).

Mixed connective tissue disease

This was described in the 1970's as a distinct entity. Though there has been some controversy about whether it is a variant of, or overlap with other CTDs clarity is best served by considering it a separate disease defined by positivity to anti-U1 RNP. ILD is common and in the form if NSIP. PH is characteristic and a patient can have both PH and ILD. Airway disease occurs occasionally in the form of bronchiolitis obliterans (BO). Pleural (and pericardial) involvement are common.

Polymyositis and dermatomyositis

ILD is common though PH is not. The relationship between inflammatory myopathy, ILD, other pulmonary problems and various serologic patterns is complex. I discussed some of those relationships in an earlier post. Since that post, a syndrome of antibody to MDA-5 has emerged as an aggressive form of ILD associated with inflammatory myopathy. ILD may arise as the first manifestation of inflammatory myopathy, lacking findings of associated myositis.

Systemic lupus erythematosis

In lupus, ILD is less characteristic than a number of other pulmonary manifestations. Reports of ILD in lupus may in some cases actually represent MCTD. Pleural (and pericardial) involvement are more prominent. Also well known are presentations resembling acute pneumonitis: lupus pneumonitis, diffuse alveolar hemorrhage and infection. PH due to SLE per se is not characteristic but pulmonary vascular disease in the form of VTE may occur in patients at special risk (eg those with accompanying antiphospholipid syndrome). Finally shrinking lung syndrome (NOT to be confused with vanishing lung syndrome) is a condition of hypoinflation of poorly understood pathophysiology, unknown whether neuropathic, myopathic or both.

I have previously posted on this general topic here.

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