Correct answer is choice C
Patient has classic features of MCTD based on overlap clinical symptoms of sjogrens( dry eyes, dry mouth) , scleroderma (skin tightening and swallowing difficulties) and also joint pains. Serology is positive for MCTD disease with positive RNP-ENA- and high Titre U1-RNP antibodies.
Most patients with MCTD have mild renal disease with membranous nephropathy being the most common feature. However some patients can progress to more aggressive forms of renal failure with diffuse proliferative changes similar to class 4 diffuse proliferative lupus nephritis and treatment should be similar to class 4 lupus regimens
Due to her relatively young age it is better to avoid cyclophosphamide due to increased side effects of gonadal toxicity in young female
The role of combination regimens ( benlysta with MMF or Voclosporin with MMF ) as initial therapy is not well established, and most experts reserve this approach for patients who do not demonstrate a clinical response within three to four months of either MMF or cyclophosphamide
MMF plus steroid based regimen followed by MMF maintenance would be best suited for this patient
MCTD and renal disease
Mixed connective tissue disease (MCTD) is a connective tissue disease characterized by the presence of anti-RNP (anti-U1 ribonucleoprotein) antibodies, and by a set of signs and symptoms that it shares with other connective tissue diseases, such as systemic lupus ery- thematosus (SLE) . Because of this clinical overlap of syndromes, the presence of high titer anti-RNP antibodies is a central feature of the diagnosis of MCTD . Importantly, one of the most distinctive features of MCTD is the relative absence of severe renal or central nervous system involvement, which may be present in other connective tissue diseases, such as SLE. This could be related to high anti-RNP titers appear to be protective against renal involvement, particularly diffuse proliferative glomerulonephritis. However in some patients a progression to severe renal disease can occur with MCTD rarely as in this patient and should be treated aggressively with Immunosuppressive therapy
Reference
https://pubmed.ncbi.nlm.nih.gov/3563525/
https://link.springer.com/chapter/10.1007/978-1-4684-8953-8_5
https://www.termedia.pl/Mixed-connective-tissue-disease-and-severe-renal-disease-an-apparent-misconception-,18,48078,1,1.html
