HIGH GRADE NEUROENDOCRINE CARCINOMA
Renal neuroendocrine carcinoma accounts for less than 1% of all epithelial renal malignancies; the average age at diagnosis is 60 years; males and females are equally affected. According to case reports and small case series, pain and gross hematuria are the most frequent clinical symptoms; many patients present with widespread metastatic disease and related symptoms.
Macroscopically, most neuroendocrine carcinomas of the kidney are located close to the renal pelvis, often surrounding the pelvicaliceal cavities. The tumor presents as a soft, whitish, gritty and necrotic renal mass, often extending into renal sinus adipose tissue. The median tumor size at diagnosis is 8 cm (range 2.5 - 23 cm). Morphologically, the tumor is composed of sheets, nests and trabeculae of poorly-differentiated small, round to fusiform cells separated by sparse intervening stroma. These cells show characteristic hyperchromatic nuclei with stippled chromatin and inconspicuous nucleoli. Their cytoplasm is hardly visible on H&E sections. Mitoses are numerous, vascular tumour emboli common, and tumour necrosis often extensive and accompanied with perivascular DNA deposition (Azzopardi phenomenon). Immunohistochemically, tumour cells show dot-like cytoplasmic staining with cytokeratins and are variably positive for neuroendocrine markers including chromogranin A, synaptophysin, CD56, and NSE. The prognosis is poor and stage dependent. Most patients present with large and locally aggressive tumor, often extending into perirenal adipose tissue at diagnosis. Regional lymph nodes and distant metastases are common. At least, 75% of patients die of their disease within one year regardless of treatment.
The patient had received radiation therapy for his brain metastases and was subsequently started on combination chemotherapy regimen with cisplatin and VP-16 (etoposide). His chemotherapy course was complicated by pancytopenia, C. difficile colitis and further weight loss with malnutrition. Despite a significant reduction of both brain metastases and the left renal mass following chemotherapy, his prognosis remains poor.
Contributed by Marie Dvorakova, M.D. and Guoping Cai, M.D.