Renal Infiltration by Diffuse Large B-Cell Lymphoma as a Rare Cause of Fanconi's Syndrome: A Case Report

We report the case of a 16-year-old female patient with a known history of coeliac disease, who presented with the complaints of diarrhea, vomiting and generalized body weakness. On examination, she was found to have dehydration, decreased power in all her limbs, cervical lymphadenopathy and hepatosplenomegaly. Investigations showed severe hypokalemia, hyponatremia, hypomagnesemia, hypoglycemia and mildly enlarged kidneys on ultrasonography. Biopsy of the duodenum confirmed the flare up of coeliac disease, while cervical lymph node biopsy was positive for atypical lymphoid infiltrate and a morphology suggestive of non-Hodgkin's lymphoma. The immune profile performed on this sample confirmed the presence of activated/non-germinal center type of diffuse large B cell lymphoma (DLBCL), which was morphologically aggressive in type. The bone marrow biopsy was hypocellular and was negative for any infiltration. The patient was suspected to have developed infiltration of one or both kidneys leading to a rare presentation of Fanconi's syndrome. She was given first dose of rituximab on the 14th day of her admission. Unfortunately, she developed cardiopulmonary arrest and expired on the next day. We recommend screening for a possible renal involvement in patients with DLBCL and in patients with unusually deranged serum electrolytes as seen in Fanconi's syndrome. Renal biopsy is considered the gold standard modality for diagnosis and if possible, an earlier sample in a patient with newly developed acute kidney injury can save future complications.