What's lurking within: When retroperitoneal calciphylaxis goes off-skin.

We present a rare case of retroperitoneal calciphylaxis in a 63-year-old woman with end-stage renal disease secondary to hypertension. The disease involved bilateral retroperitoneum and was incidentally found on CT imaging performed for renal transplant evaluation. Imaging revealed diffuse soft tissue hyperattenuation, calcified nodules and cortical calcifications. Subsequent biopsy of the perinephric fat demonstrated fat necrosis and vascular wall calcification, consistent with calciphylaxis. The patient was medically cleared for renal transplantation and has shown improved kidney function on follow-up. While both cutaneous and visceral calciphylaxis typically carry poor prognoses, this case represents an indolent visceral variant discovered in the absence of cutaneous or systemic complications.