Atypical carcinoid of the primary kidney with retroperitoneal metastasis 15 years later: A case report and literature review

Abstract

Primary renal neuroendocrine tumors (NETs) are extremely rare among renal malignancies. According to pathological manifestations, carcinoid can be divided into four types: typical carcinoid, atypical carcinoid, large cell and small cell neuroendocrine carcinoma. Primary or secondary retroperitoneal carcinoid is even rarer than renal carcinoid. This article reports a patient with renal carcinoid complicated with retroperitoneal metastasis, who developed retroperitoneal metastasis 15 years after radical nephrectomy. Through the analysis of this case and the combination of the existing published literature, it is aimed to provide valuable references for clinicians in treating patients with renal carcinoid or with metastasis.

1 Background

Neuroendocrine tumors originate from neuroendocrine cells, which are distributed throughout the body. Therefore, neuroendocrine tumors can occur in any part of the body. The gastrointestinal and other digestive systems are the most common sites of occurrence, accounting for about 2/3 of all neuroendocrine tumors. Neuroendocrine tumors originating from the kidney are very rare, accounting for less than 1 % of renal epithelial malignancies. And there is currently no case record of renal carcinoid metastasis to the retroperitoneum. Here, we report a case of a 39-year-old female with primary renal carcinoid with retroperitoneal metastasis, who developed metastasis 15 years after radical nephrectomy. Based on the induction and analysis of the literature review, this article discusses the clinical features, differential diagnosis, imaging features, pathological manifestations, treatment options and prognosis of this case.

2 Case presentation

Initial Presentation: A 39-year-old female presented to the outpatient department due to left lumbar pain for 4 days. Physical examination showed no tenderness or percussion pain in the bilateral kidney areas, no tenderness or masses in the bilateral ureters, and no tenderness or percussion pain in the bladder area. She was admitted to the hospital after a left renal mass was detected by CT examination. There was no macroscopic hematuria, no frequency, urgency, or dysuria. There were no clinical manifestations such as fever, chills, night sweats, or fatigue since the onset of the disease. The general condition was acceptable, and no abnormalities were found on physical examination.

CT examination: A round slightly low-density mass was seen in the left renal parenchyma. The lesion locally protruded from the renal contour, with a maximum diameter of about 4.7cm × 4.3cm. The mass had a clear boundary with the renal parenchyma, and the internal density was relatively uniform. After enhancement, it showed enhancement, and the density was relatively uniform. The adjacent renal parenchyma was compressed, and the renal pelvis was slightly narrowed. It was considered a tumor, and renal cancer was more likely.

Initial Treatment and Pathology: After completing the preoperative related examinations and having no obvious surgical contraindications, left radical nephrectomy was performed under general anesthesia. After the operation, the left kidney, perirenal fat, and two renal hilar lymph nodes were sent for pathology. The pathological diagnosis was (left) papillary renal cell carcinoma of the kidney. The tumor volume was 5cm × 5cm × 4cm; the cancer tissue invaded the perirenal fat capsule; 1 out of 1 (1+/1) lymph node beside the left renal hilum showed cancer metastasis. At that time, immunohistochemistry was not done, and it was only regarded as an ordinary papillary renal cell carcinoma according to the pathology.

15 Years Later: She was admitted to the hospital due to the discovery of a left renal area mass for 1 month during a physical examination. There was no frequency, urgency, or dysuria, no macroscopic hematuria, no fever, fatigue, lumbosacral discomfort, no headache, dizziness, nausea, or vomiting, and the physical examination showed no abnormalities. The left renal tumer resection was performed 15 years ago. After the review, a whole abdomen (hepatobiliary pancreas spleen + retroperitoneum + pelvic cavity) CT plain scan + enhanced examination was performed due to the discovery of a mass in the left renal area: changes after left nephrectomy, and multiple nodular and mass-like soft tissue density shadows were locally seen in the left retroperitoneum, with some fusion. The larger cross-sectional size was about 40mm × 29mm × 39mm, with cystic changes inside. The local boundary with the left adrenal gland body and the left psoas major muscle was not clear. The right edge was connected with the residual left renal vein. The local abdominal aorta and lumbar artery on the left side seemed to participate in the blood supply. The plain scan CT value was about 54HU, and after enhancement, it showed mild enhancement, and there was no enhancement in the central cystic change area. The CT values in the three phases were about 70HU, 71HU, and 75HU. In addition, there were multiple soft tissue masses of different sizes at the lower edge, with no obvious cystic change area. The plain scan CT value was about 54HU, and after enhancement, it showed obvious uniform enhancement. The CT values in the three phases were 79HU, 84HU, and 75HU (as shown in Fig. 1 ).

Treatment and Pathology 15 Years Later: After completing the preoperative related examinations and having no obvious surgical contraindications, left laparoscopic retroperitoneal mass resection was performed under general anesthesia. The postoperative pathological section was considered recurrent or metastatic (left retroperitoneum) atypical carcinoid. There was no cancer tissue invasion in the nerves and blood vessels. Adrenal tissue was seen around, and there was no tumor involvement. Immunohistochemical results: Cancer cells Syn(+), CgA(−), CD56(+), P504S (weak+), SSTR2 (strong+), Vim(+), AE1/AE3 (weak+), CD10 (focal+), EMA (focal+), CK7(−), Pax-2(−), WT1(−), Pax-8(−), ER(−), Inhibina(−), p53 (unequal intensity +, wild type), Ki-67 (+, about 5 %)(as shown in Figs. 2–3 ).

Considering that the retroperitoneal atypical carcinoid may be recurrent or metastatic, immunohistochemistry was performed again on the pathological sections 15 years ago(as shown in Figs. 4–5 ).