Primary renal carcinoid tumors: Three case reports

Rationale: Primary renal carcinoid tumors are very rare and only about 100 cases have been reported in the medical literature. There are even fewer articles on the imaging manifestations of primary renal carcinoid tumors.

Patient concerns: We present 3 cases of patients with lumbago and hematuria. These were cases of primary renal carcinoid tumors with initial suspicion of suprarenal epithelioma.

Diagnoses: Renal lesions were detected on abdomen computed tomography (CT) imaging. The 3 cases presented as solid/cystic solid renal mass with uniform or non-uniform density, calcification in the mass, and enhanced heterogeneity.

Interventions: The laparoscopic partial/radical nephrectomy were performed.

Outcomes: The postoperative histological diagnosis were primary renal carcinoid tumors. Case 2 been lost to follow-up in 3 patients, and the other 2 patients (Case 1 and 3) are still alive. Case 1 had intrahepatic metastases.

Lessons: Primary renal carcinoid tumors mostly present as solid mass/cystic solid mass with calcification and delayed enhancement of heterogeneity on CT imaging, but the diagnosis depends on pathological diagnosis. Hence, raising awareness of the CT features of the rare tumor in the kidney may broaden the knowledge base of radiologists.