Unique Dystrophic Xanthomatous Reaction in Renal Parenchyma Due to T Cell Lymphoma

Introduction: While B-lymphocyte and plasma cell-associated kidney involvement have been described extensively in literature, kidney involvement by T-cell lymphoma remains a rare phenomenon. Rare case reports have described an interstitial nephritis-like picture in association with peripheral T cell lymphoma. We describe a unique dystrophic xanthomatous reaction in the kidney parenchyma in association with interstitial involvement with a CD8+ve T cell lymphoma. Case Description: A 23-year-old woman with autoimmune encephalitis, seizure disorder hypogammaglobulinemia due to Common Variable Immune Deficiency (CVID), and CD3+/CD8+ T cell lymphoproliferative involvement of the liver and bone marrow, was admitted for seizures, and found to have non-oliguric acute kidney injury (Creatinine (Cr) of 4.42 mg/dL (baseline 1) with severe metabolic acidosis (serum bicarbonate of 9 mmol/L). Urine showed hematuria and proteinuria of 1.6g/g. Kidney ultrasound showed bilateral enlarged kidneys measuring 14.8cm and 16cm with diffuse infiltrative process. Kidney biopsy showed unremarkable glomeruli and an abnormal-appearing tubulointerstitium in the form of diffuse interstitial sheets and intra-tubular collections of foam cells/histiocytes, along with a patchy infiltrate of atypical T-lymphoid cells of CD3/CD8-lineage. (image 1) She was started on methotrexate 5mg/m2 weekly and prednisone 1mg/kg by her oncologist. On follow up, kidney function had improved with most recent Cr of 1.98mg/dL. Discussion: We describe a unique histologic reaction (dystrophic xanthoma cells in the interstitium and within dilated kidney tubules) in association with interstitial involvement by a T-cell lymphoma, which has not been described before in the kidney, although such xanthomatous reaction has been described for cutaneous T-cell lymphomas. Awareness is vital in identifying such rare kidney histomorphology in association with T-cell lymphomas.