Primary Renal Carcinoid Tumor

Abstract

Primary carcinoid tumors originating in a normal kidney are exceptionally rare. We describe a case of a 52-year-old woman who presented with vague back pain and was found to have a 4-cm mass in the medial aspect of the left kidney. Radical nephrectomy and retroperitoneal lymphadenectomy were performed. Histopathology revealed a typical carcinoid tumor with 1 out of 17 lymph nodes involved. She has no evidence of recurrence or metastasis on 7-month follow-up. KEYWORDS: kidney, carcinoid, renal DOMAIN: urology CASE PRESENTATIONA 52-year-old woman presented to her primary medical doctor with a 3-year history of lower back pain and right-sided posterior rib pain. A CT scan of the abdomen and pelvis revealed a 4-cm focally calcified mass arising from the medial aspect of the left kidney. The chest X-ray was normal. The patient was referred to urology for evaluation of a presumed left-sided renal cell carcinoma. There was no elevation of serum or urine catecholamines. She underwent a left radical nephrectomy with a retroperitoneal lymph node dissection. Grossly, there was a well-circumscribed, homogenously yellow mass measuring 3.2 cm in its greatest diameter projecting into the renal hilum (Fig. 1). The adrenal gland was normal. Histopathological sections of the mass showed a typical carcinoid tumor consisting of nests of small uniform cells with scanty cytoplasm and round nuclei that showed finely granular chromatin distribution (Fig. 2). Vascular invasion was identified, as was invasion into the renal capsule and perirenal fat; no invasion of Gerota's fascia was seen. One out of 17 lymph nodes showed metastatic carcinoid tumor. Immunoperoxidase staining showed positivity for cytokeratin and synaptophysin, confirming the diagnosis of carcinoid tumor. The postoperative course was uneventful. Seven months after surgery, her serum 5-hydroxy indole acetic acid levels (5-HIAA) were normal and indium-111 octeotride scintigraphy was negative. She has no evidence of recurrence on CT or bone scan done at 6 months postoperatively.

Carcinoid tumor arising in a horseshoe kidney

“…It has been suggested that they might originate from neuroendocrine cells associated with intestinal metaplasia of the renal collecting system or neuroendocrine cells found within teratomatous intestinal or respiratory epithelium within the kidney [1,5]. These theories could explain that renal carcinoid tumor is more frequent in HSK, possibly because abnormalities or teratomatous elements in epithelium are more common in these kidneys [6].…”

Primary renal well‐differentiated neuroendocrine tumour (carcinoid): next‐generation sequencing study of 11 cases

“…Primary well‐differentiated renal NET (hereafter referred to as renal NET) is rare, with ~100 cases reported in the literature, mainly as case reports or small series (the largest original study described 21 tumours) …”

Primary renal carcinoid tumor: A radiologic review

“…The fourth suggests concurrent congenital renal abnormalities ( 17 , 18 ). And the last hypothesis suggests activation of gene sequences in multipotent primitive stem cells ( 5 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ).…”