Nephropathic cystinosis in a kidney transplant recipient: A mesenteric lymph node demonstrates positive birefringent crystals

We report a kidney transplant recipient in their early twenties with infantile nephropathic cystinosis and EBV viremia who presented with right flank pain, night sweats, and right lower quadrant abdominal tenderness. A CT scan of the abdomen demonstrated mesenteric adenopathy. A laparoscopic mesenteric lymph node biopsy was performed with a concern for post-transplant lymphoproliferative disorder (PTLD). Positive birefringent crystals were identified within the tissue macrophages of benign reactive lymph nodes. Immunohistochemical staining and flow cytometry confirmed polyclonal B-cells without evidence of a clonal B-cell population supportive of PTLD. We report intracellular birefringent crystals within lymph nodes in a patient with infantile cystinosis. We review the clinical history of the patient and the pathologic analysis to evaluate for possible PTLD.