A 56-year-old woman with a history of hypertension, hyperlipidemia, mixed connective tissue disease (MCTD), and hypothyroidism presents with respiratory failure secondary to influenza A and Staphylococcus aureus pneumonia. She is admitted to the ICU for invasive mechanical ventilation.
Titers of which of the following antibodies do you most expect to be positive?
A. Anti-LaCorrect Answer: D
There are five diffuse connective tissue disorders (DCTDs):
However, up to 25% of patients experience symptoms that may evolve from one disorder into another over time or have characteristics of several disorders at presentation, and thus are said to have an “overlap syndrome.” MCTD, also known as Sharp syndrome, is one such “overall syndrome” and shares clinical similarities with SLE, SS, and PM. Several sets of diagnostic criteria exist for MCTD, but the requirement for a positive Anti-U1-RNP antibody is universal among them. The Kasukawa criteria are one such, well-accepted, diagnostic criteria:
Aside from musculoskeletal manifestations (above), other clinical features of MCTD include pulmonary hypertension (affecting 10%-50% patients), interstitial lung disease (ILD) (affecting 47%-78% patients), oroesophageal involvement (affecting 64% patients), cardiovascular involvement (13%-65% patients), and renal involvement (5%-36% patients).
Among the other answer choices, anti-La is seen in primary Sjogren syndrome, anti-dsDNA is seen in SLE, and anti-PR3 and anti-MPO are seen in ANCAvasculitis.
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