Answer to the last #DiagnosticDilemma
Now open: Certificate Course in Management of Covid-19 by Govt. Of Gujarat and PlexusMDKnow more...Now open: Certificate Course in Management of Covid-19 by Govt. Of Gujarat and PlexusMDKnow more...
The answer to the last Diagnostic Dilemma (A 37-year-old woman presented with a 3-year history of episodic swelling and pain in her left ear. The current episode was accompanied by decreased urine volume, hypertension, oedema of both legs) is C ANCA-associated glomerulonephritis

On examination, the patient had a raised blood pressure of 160/90 mm Hg. She had a markedly tender and inflamed left ear pinna—sparing the ear lobe, the auditory canal, and tympanic membrane, which were all normal. No discharge or cervical lymphadenopathy was found, and the right ear, both eyes, and nose were unremarkable. She had 1+ bilateral pitting oedema in her legs: barely detectable impression when finger is pressed into the skin. A chest x-ray was normal.

Urinalysis showed ten to 20 dysmorphic erythrocytes per high power field and 1+ proteinuria. Laboratory investigations showed a serum creatinine concentration of 4·2 mg/dL (normal 0·51–0·95), which had increased from 0·9 mg/dL 1 year earlier. The patient's complement levels were normal, and an anti-nuclear antibody test was negative. However, she tested positive for both anti-myeloperoxidase antibodies and perinuclear antineutrophil cytoplasmic antibodies. A random plasma glucose concentration was 99 mg/dL (normal 70–140), and the patient's serum albumin concentration was 4·1 mg/dL (normal 3·4–5·4).

Histopathological examination of a sample taken from a biopsy of the patient's kidney showed active cellular crescents with a ruptured glomerular basement membrane and marked tubulointerstitial inflammation. The author diagnosed pauci-immune crescentic glomerulonephritis with relapsing polychondritis.

2 days after admission, the patient's serum creatinine concentration rose to 5·6 mg/dL, which required seven sessions of plasmapheresis. She was given both oral cyclophosphamide at a dose of 2 mg per kg per day and intravenous methylprednisolone at a dose of 500 mg a day for 3 days followed by oral prednisolone 1 mg per kg per day, which induced clinical remission of the polychondritis and reduced the serum creatinine concentration to 2·4 mg/dL at day 25. After 4 months, the oral cyclophosphamide was replaced with azathioprine and the patient has not had any recurrence of the problems during 2 years of follow-up.

For Diagnostic Dilemma, refer