Abstract: TH-PO1101
Butterfly Effect: Complement-Mediated Thrombotic Microangiopathy Masquerading as Lupus Nephritis
Session Information
- Pathology and Lab Medicine
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1700 Pathology and Lab Medicine
Authors
- Asghar, Faiza B., McLaren Flint Hospital, Flint, Michigan, United States
- Ghumman, Harneet Kaur, McLaren Flint Hospital, Flint, Michigan, United States
- Shrestha, Anjela, McLaren Flint Hospital, Flint, Michigan, United States
- Mokhtari, Mohsen, McLaren Flint Hospital, Flint, Michigan, United States
- Abdalla, Mohamed, McLaren Flint Hospital, Flint, Michigan, United States
Introduction
Thrombotic microangiopathy (TMA) is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and end-organ injury, most commonly involving the kidneys. The differential diagnosis includes thrombotic thrombocytopenic purpura (TTP), lupus-associated TMA, malignant hypertension, and atypical hemolytic uremic syndrome (aHUS). Distinguishing these entities is critical, as treatment and outcomes differ significantly.
Case Description
A 31-year-old female with Hashimoto thyroiditis presented with fatigue, weakness, arthralgias, and a malar-like facial rash after outdoor exposure. Outpatient workup revealed ANA positivity at 1:640, raising concern for autoimmune disease. She later presented with severe acute renal failure (creatinine 17 mg/dL), hypertensive emergency. Laboratory evaluation demonstrated anemia, leukocytosis, and mild thrombocytopenia, prompting emergent hemodialysis. Differential diagnoses included lupus nephritis with TMA, TTP, malignant hypertension, and other autoimmune etiologies. Lupus serologies and scleroderma workup were negative, and ADAMTS13 activity was not consistent with TTP. There was no preceding diarrheal illness suggestive of Shiga toxin-associated disease. Renal biopsy demonstrated TMA without immune complex deposition. In the absence of secondary causes, complement-mediated TMA, specifically aHUS, became strongly suspected. She was transferred to a tertiary center for initiation of eculizumab. She is currently improving clinically with recovering renal function and urine output. Hemodialysis has been discontinued, and she remains on eculizumab with ongoing nephrology and hematology follow-up. Genetic testing remains pending.
Discussion
This case highlights the diagnostic complexity of TMA in patients with overlapping autoimmune features. Positive ANA and malar-like rash initially suggested lupus-associated disease. Negative confirmatory serologies, preserved ADAMTS13 activity, and absence of immune complex deposition supported complement-mediated TMA. Early recognition of aHUS is essential, as prompt complement inhibition therapy may improve renal recovery and reduce long-term dialysis dependence.
Teaching Points:
1. Consider aHUS in severe renal dysfunction with unexplained TMA after exclusion of secondary causes.
2. Autoimmune features may obscure complement-mediated TMA.
3. Early complement inhibition therapy may improve renal outcomes.