1. Association of ANA pattern with CTD-ILDs
We often talk about ANA titers & pattern in our ILD evaluations – what do they signify?
- Cut-off for positive test suggested at 1:160
- Variability based on lab/technician
- 25-30% of health controls with low Ab titers
- 56% +ANA with ILD of unclear cause, despite lower rate of CTD diagnosis (4-20%) in ILD population
- Increasing age associated with higher prevalence of ANA positivity
General associations to be aware of:
- Homogenous –> dsDNA –> SLE
- Speckled –> MCTD, Sjogren, SLE, DM
- Centromeric or Nucleolar –> SSc
- Cytoplasmic –> anti-synthetase syndrome
2. Acute interstitial pneumonia/Hamman-Rich Syndrome
What are the clinical characteristics and prognosis of this rare illness?
- Rapidly progressive (1-2 weeks) hypoxemic respiratory failure with high mortality (~50%), with bilateral GGOs and consolidation within dependent lung, no clear trigger (ddx ARDS) and without antecedent ILD (ddx flare ILD, esp IPF)
- Pathology shows diffuse alveolar damage, alveolar wall thickening and pneumocyte hyperplasia
- Progresses to pattern similar to fibrotic NSIP Clinical course and lung function change of idiopathic nonspecific interstitial pneumonia
Image source: European Respiratory Journal 2009 33:68-76.
A retrospective analysis of 83 patients with radiological & pathological criteria for iNSIP conducted in the pre-antifibrotic era (between 1991-2006).
Interesting findings included:
- 10% of patients with iNSIP developed clinically manifest CTD during follow-up
- Scleroderma, PM/DM, RA, MCTD, PMR
- These patients tended to be younger and did not have increased risk for recurrence
- Deterioration of FVC at 6 months correlated most strongly with disease-specific mortality
From Jane Dematte:
One thing I will bring out with respect to your teaching and a question for our rheum colleagues:
Our lab currently DO NOT report CYTOPLASMIC AB.
This is a often a fast early clue to an antisynthetase AB as they are cytoplasmic.
We only report our nuclear AB.
I wonder if we should approach our lab about looking for and reporting out cytoplasmic AB. This would be helpful in some of our ICU cases with RP ILD
From Carrie Richardson:
That’s a great idea, Jane. I don’t see why they couldn’t report cytoplasmic Abs. I can chat with some of my rheum colleagues to see if they’ve ever approached the lab with this request and what the outcome was.