Case presentation

An 80-year-old woman, with a medical history of hypertension and dyslipidemia, was diagnosed incidentally with a left renal mass on an abdominal computed tomography (CT) scan performed mainly to investigate acute abdominal pain. The CT scan showed a heterogeneous renal cyst with regular contours, in the renal medulla and it was classified Bosniak 4. Then, the patient underwent an enlarged left nephrectomy. Macroscopically, it was a fairly well-defined nodular formation, grayish-white with ocher-yellow foci. It measured 3 cm and it was located in the renal medulla (Figure 1). Histological examination found tubular formations merging with bland spindle cells and a mucinous stroma (Figure 2). Tumour cells express CK7 and AMACR (Figure 3, 4). The tumour was classified pT1N0M0. The outcome was favourable, free of recurrence or complications after eight months of follow-up.