Case Quiz (December 2024)
A previously healthy, immunized 6-year-old female presented to the pediatric emergency department with a 6-day history of fever reaching 39°C, sore throat, abdominal pain, vomiting, headache, and a 3-day history of bilateral eye puffiness. Her symptoms were also notable for strong-smelling urine. She had been evaluated by her primary care physician on day 2 of illness, with negative rapid and confirmatory strep tests.
Upon arrival at the emergency department, the patient was afebrile, and her vital signs were within normal limits. On examination, she appeared ill, with periorbital edema but was not in acute distress. The oropharyngeal exam revealed pharyngeal erythema, tonsillar exudate, and palatal petechiae. Bilateral anterior and posterior cervical adenopathy was noted. Abdominal exam revealed tenderness and involuntary guarding in the right upper and lower quadrants, as well as splenomegaly. Hepatomegaly could not be evaluated due to significant discomfort. The rest of the examination was otherwise unremarkable.
The complete blood count revealed neutropenia, atypical lymphocytosis, and thrombocytopenia. The complete metabolic panel showed mild hypoalbuminemia, elevated alkaline phosphatase levels, and transaminitis. The partial thromboplastin time was prolonged. Both ESR rate and CRP were elevated.
Urinalysis was positive for protein and leukocyte esterase, but the urine culture was negative.
A chest radiograph showed a trace right pleural effusion. Abdominal ultrasound findings included hepatosplenomegaly, moderate ascites, acalculous cholecystitis, possible cholangitis, edema and enlargement of the left kidney, and a distended appendix with surrounding fluid. Additionally, multiple enlarged lymph nodes were observed in the hepatic and splenic hila as well as throughout the mesentery.
Consultations with surgery and gastroenterology were requested. Toxicology tests and a comprehensive viral panel, including Epstein-Barr virus (EBV), cytomegalovirus, herpes viruses, and hepatitis serologies, were ordered. The patient was started on piperacillin/tazobactam and admitted under the care of the Gastroenterology Liver Team.
Case Answer (December 2024)
C1q nephropathy associated with Epstein-Barr virus (EBV) infection
EBV is very common with typical manifestations including fever, petechial or exudative pharyngitis, cervical lymphadenopathy, hepatosplenomegaly, and atypical lymphocytosis.Some degree of thrombocytopenia is a well-documented complication.
C1q nephropathy is a proliferative glomerulopathy with extensive mesangial deposition of C1q. Mostly acceptable diagnostic criteria of C1q nephropathy are mesangial immune deposits that stain dominantly or co-dominantly for C1q, corresponding mesangial electron dense deposits on electron microscopic examination, and the clinical setting of steroid-resistant proteinuria without evidence of systemic lupus erythematosus.
EBV infection may induce renal diseases, most frequently acute interstitial nephritis during the course of infectious mononucleosis. Occasional occurrences of glomerular diseases such as IgA nephropathy, steroid-dependent minimal change nephrotic syndrome, and HUS in patients with infectious mononucleosis have also been reported.
the causal relationship between EBV infection and C1q nephropathy cannot be completely excluded in our patient on the basis of coincidental onset of infectious mononucleosis and the foamy urine and the frequent negative result of in situ hybridization in EBV-induced nephritis
