MKSAP Quiz: Renal symptoms following squamous-cell lung cancer resection
MKSAP Quiz: Renal symptoms following squamous-cell lung cancer resection
A 65-year-old man is evaluated for hypoalbuminemia, hyperlipidemia, and slowly progressive proteinuria that have developed over 1 year. One year ago, he underwent squamous-cell lung cancer resection.
On physical examination, blood pressure is 150/90 mm Hg. Cardiac examination reveals a normal S1 and S2 without rubs or gallops. Pulmonary examination shows decreased breath sounds in the right lower lobe consistent with his previous surgery. Abdominal examination is normal. There is 3+ edema of the lower extremities.
Laboratory studies
| Blood urea nitrogen | 17 mg/dL (6.07 mmol/L) |
| Creatinine | 1.0 mg/dL (88.42 µmol/L) |
| Urinalysis | Specific gravity 1.020, numerous granular casts and oval fat bodies/hpf |
| 24-hour urinary protein excretion | 15 g/24 h |
Chest radiograph reveals a new 1-cm nodule in the left upper lobe.
Which of the following is the most likely cause of this patient's renal symptoms?
A. Minimal change glomerulopathy
B. Focal segmental glomerulosclerosis
C. Membranous nephropathy
D. IgA glomerulonephritis
E. Antineutrophil cytoplasmic autoantibody–associated vasculitis
MKSAP Answer and Critique
The correct answer is C) Membranous nephropathy. This item is available online to MKSAP 14 subscribers in the Nephrology section, Item 16.
This patient most likely has membranous nephropathy. Suspicion for this condition is raised in patients older than 55 years of age. The presence of a slowly progressive nephrotic syndrome suggests the possibility of solid tumor-associated membranous nephropathy. In a patient with a history of squamous-cell lung cancer and a new lung nodule in the left upper lobe that may represent recurrent cancer, the association between membranous nephropathy and a solid tumor of the lung is highly likely.
Minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy are all causes of the nephrotic syndrome. However, membranous nephropathy is most frequently associated with solid tumors. IgA glomerulonephritis and antineutrophil cytoplasmic autoantibody–associated small-vessel vasculitis are unlikely in the absence of hematuria on urinalysis. Similarly, neither of these conditions would be associated with a urinary protein excretion of 15 g/24 h.