Contributed by Alicia F Liang, MD and Sheldon Bastacky, MD
A 42-year-old previously healthy male with a past medical history significant only for hyperlipidemia presented with weakness, fatigue and edema of the face and extremities. Initial laboratory studies demonstrated anemia (9.8 mg/dL), renal insufficiency (creatinine 2.3 mg/dL), a weak positive ANA of 1:80 with nucleolar pattern, elevated rheumatoid factor, and negative hepatitis B and C serologies. Urine sediment contained a small number of erythrocytes and white blood cells, and granular and hyaline casts. Because of the patient's clinical picture, including moderate anemia, a serologic evaluation for parvovirus B19 was performed, which was positive for both IgG and IgM antibodies. Additionally, because of renal failure, a renal biopsy was performed.
Light microscopic examination of the glomeruli demonstrated mild-to-moderate mesangial and focal endocapillary proliferation (see image 1). Increased numbers of neutrophils and mononuclear white blood cells were present within many glomeruli. Silver stain (image 2) revealed occasional bubbles within the basement membrane, but no spikes were identified. There were no sclerosing lesions, necrotizing lesions, or crescents. By immunofluorescence a full-house pseudolinear and mesangial staining pattern was seen; C3 showed maximum intensity [4+], and IgG, IgM, IgA, kappa and lambda were only slight weaker [3+]. Electron microscopic examination was remarkable for scattered small subendothelial and mesangial immune complex deposits (images 3, 4, and 5), and podocyte foot process effacement.