A 42-year-old woman reported a two-week history of generalized fatigue, arthralgia, and a malar rash. She subsequently sought evaluation by her primary care physician, where abnormal urinalysis findings, including proteinuria and hematuria, were identified.
Previous diagnoses:
Arterial hypertension
Vital parameters:
BP: 145/85 mmHg
HR: 88/min
SpO2: 97 %
Physical examination:
Skin: Malar rash present; no purpura
Heart: clear, rhythmic
Lungs: vesicular breathing on both sides
Abdomen: soft, regular bowel sounds, no tenderness
Laboratory:
Hemoglobin (12.4–16.1) g/dL: 9.8
White blood cells: (4.0–11.8) Mrd/L: 3.5
Albumin (34–50) g/L: 32
Creatinine (0.7-1.2) mg/dL: 1.8
GFR (CKD-EPI) mL/min: 32
CrP (< 5) mg/L: 6.8
Immunology:
C3 (90-170) mg/dL: 38
C4 (12-36) mg/dL: 7
ANA (< 1:80) Titer: 1:640
Anti-dsDNA antibody: 80 IU/ml
c-ANCA (< 1:20): negative
p-ANCA (< 1:20): negative
GBM-AB (< 7) U/mL: negative
Urine:
Urine protein-creatinine ratio (uPCR) mg/g: 3850
Urine sediment:
Numerous red blood cells, including acanthocytes; few leukocytes; positive granular casts; and occasional cellular casts
The patient exhibited hematuria, heavy proteinuria, malar rash, arthralgia, pancytopenia, hypocomplementemia, and a positive anti–dsDNA antibody, all strongly suggestive of systemic lupus erythematosus.
Based on these clinical and immunological features, lupus nephritis was strongly suspected, and a renal biopsy was deemed indicated.
Note related to annotations: To avoid obscuring the lesions, the annotations are deliberately positioned close to, but not directly over, the lesion areas.
Pathological diagnosis: Diffuse lupus nephritis with diffuse wire loop lesions, acute tubulointerstitial nephritis (40% in cortex), Lupus nephritis, Class IV(A) (ISN/RPS 2004).
Light microscopic findings:Three renal cortex specimens contained about 23-30 glomeruli, with no obsolescent glomeruli. In glomeruli, the glomerular capillary walls were noticeably thickened, wire loop lesions were present with widespread subendothelial deposits, and irregular double contour of the glomerular basement membranes. Hyaline thrombi were also observed within some glomerular capillary lumens. Mesangial proliferative lesions and segmental endocapillary proliferative lesions were also observed. Necrotic and crescentic lesions were not evident. Spike formation of the glomerular basement membranes was inconspicuous.
In the tubulointerstitium, moderate inflammatory cell infiltration was observed, covering approximately 30-40% of the cortex. Interstitial fibrosis and lymphocyte infiltration with neutrophils and eosinophils were present, consistent with tubulointerstitial nephritis.
No arterial lesions were evident.
Immunofluorescence study (4 glomeruli): Full house pattern of deposition of IgG, IgA, and IgM, and complements were observed as mesangial + peripheral (partial fringe pattern), granular pattern.
IgM (1+) mesangial = peripheral (partial fringe pattern), granular
IgG (2+) mesangial = peripheral (partial fringe pattern), granular
IgA (2+) mesangial = peripheral (partial fringe pattern), granular
C1q (2+) mesangial = peripheral (partial fringe pattern), granular
C3c (2+) mesangial = peripheral (partial fringe pattern), granular
C4 (-)
Electron microscopy findings: Mesangial electron dense deposits were observed in the glomeruli, with prominent subendothelial deposits in the capillary walls, some of which formed wire loops. Mild subepithelial deposits were also observed in an irregular distribution. Organized fingerprint structures were observed within the deposits. Swelling and loss of fenestra were observed in the glomerular endothelial cells, and tubuloreticular inclusions were observed in the cytoplasm. Effacement of foot processes of the podocytes was also observed. Mesangial proliferative lesions were observed, corresponding to lupus nephritis.
Pathological diagnosis:Diffuse wire loop lesions were observed in almost all glomeruli, corresponding to active lupus nephritis Class IV (A). In addition, focal tubulointerstitial nephritis with intense inflammatory cell infiltration was also observed in approximately 30-40% of the cortex. Electron microscopy findings revealed mesangial and subendothelial electron dense deposits. Scattered subepithelial electron dense deposits were also seen, but no Class V membranous lupus nephritis was evident. Pathological diagnosis is lupus nephritis, Class IV(A) (ISN/RPS 2004).