Late Diagnosis of E148Q Mutation-Positive Familial Mediterranean Fever in a Kidney Transplant Patient With Fever of Unknown Origin: A Case Report.

Fever of unknown origin is a rare condition after solid organ transplant and is generally associated with atypical infections (eg, tuberculosis, fungal infections) and/or lymphoproliferative disorders. Here, we present a kidney transplant patient with a late diagnosis of E148Q mutation-positive familial Mediterranean fever as the cause of fever of unknown origin. A 22-year-old female patient with a previous history of 4 years of hemodialysis and unknown primary renal disease received a deceased-donor kidney transplant at our center 5 years previously. She had an uneventful course in the first 3 years following transplant. After this period, she was hospitalized 3 times during a 4-month period with fever, nausea, vomiting, and atypical abdominal pain. At that time, hemogram results were unremarkable, except for mild leukocytosis and slightly elevated acute-phase reactants; blood, urine, and throat cultures were negative, and there were no remarkable findings on imaging tests. Fever was controlled within 48 hours by administering empiric ampicillin-sulbactam therapy and discontinuing immunosuppressive treatment except steroids. Three successive hospital admissions owing to similar complaints suggested periodic fever syndrome, and therapy with 1 g/day colchicine led to an excellent clinical response with no recurrence of fever or other symptoms. An FMF gene mutation analysis revealed heterozygous E148Q mutation positivity. Continuing the current treatment regimen, the patient did well during at approximately 1.5 years of follow-up. In the Mediterranean region population, familial Mediterranean fever should be considered in the diagnosis of fever of unknown origin in patients who have undergone renal transplant. E148Q mutation-positive familial Mediterranean fever has a subclinical course and renal manifestations that differ from AA amyloidosis during childhood and may be responsible for de novo familial Mediterranean fever after renal transplantation.