neuroendocrine neoplasms are uncommon tumors of the kidney that may arise in various organs and tissues , including in those that do not normally contain neuroendocrine cells . these tumors are characterized by the presence of a neural and an epithelial component in conjunction with each other . the biological behavior of these tumors ranges over a spectrum , and can only be judged accurately by their metastatic tendency . there have been only a couple of series of such tumors of the kidney reported in literature . we report here a case of a large - cell neuroendocrine carcinoma ( lcnec ) of the kidney with appropriate immunohistochemistry . imaging of the abdomen revealed a renal tumor , abutting the undersurface of the right lobe of the liver with a thrombus in the renal vein . resection of a portion of the right diaphragmatic crus and of the renal vein thrombus was done . gross examination revealed a lobulated , firm , grey - white tumor along with necrosis and a renal vein thrombus . microscopy evidence indicated the composition of trabeculae , pseudorosettes , and strands of medium - to - large - sized tumor cells possessing moderate eosinophilic cytoplasm and vesicular nuclei in the tumor lobules . the nuclei had fine chromatin and prominent nucleoli and the cells were separated by a fibrovascular stroma . mitotic count was > 20 per 10 high - power fields [ figure 1 ] . ribbons and cords of tumor cells separated by stroma ( h and e , 10 ) immunohistochemistry revealed positive staining ( > 10 high - power fields ) for cytokeratin , neuron - specific enolase ( nse ) , chromogranin a , and synaptophysin , and negative staining for vimentin [ figure 2 ] . tumor cells positive for chromogranin ( ihc , 40 ) on the basis of these results , a diagnosis of lcnec was made . the patient has completed one year of follow - up and remains disease - free at the time of this report . these tumors can be admixed with other histological types such as adenocarcinoma or squamous cell carcinoma . there have been only a couple of series of renal lcnec reported in the english literature . the nomenclature and classification of nets at different sites ( lung , gi tract ) , remains controversial . the recent who classification of nets is as follows : well - differentiated net ( carcinoid ) , well - differentiated neuroendocrine carcinoma ( atypical carcinoid ) , and poorly differentiated neuroendocrine carcinomas ( small cell carcinoma ) and lcnec . the renal net patients present with hematuria and abdominal pain , and the tumors are typically advanced at the time of diagnosis . grossly , the tumor appears lobulated with a tan or grey cut surface . microscopically , lcnec is composed of tumor cells that are arranged in organoid nests , trabeculae , rosette - like , and palisading patterns . immunohistochemistry shows positivity for nse , chromogranin a , synaptophysin , and leu 7 ( cd57 ) . an lcnec can be mistaken for a high - grade renal cell carcinoma or urothelial carcinoma . immunohistochemistry comes to the rescue , with at least one of the neuroendocrine markers being positive . in summary , the lcnec entity 's awareness and its occurrence in the kidney along with the appropriate usage of immunohistochemical techniques would enable the establishment of its diagnosis .
neuroendocrine tumors are rare entities which can arise in various sites of the body . 
 the presence of both neural and endocrine elements in conjunction characterises these tumors pathologically . 
 most of these tumors are non secretory in nature , and arise in organs where there may not be any neuroendocrine elements . 
 carcinoid tumors are the most common entities reported in the kidney . 
 there have been only a couple of case series of non - carcinoid neuroendocrine tumors of the kidney reported in literature . 
 surgical resection appears to be the best available treatment modality . 
 chemotherapy has been attempted with dismal results . 
 the biological behaviour is determined by the occurrence of metastases to the liver or lung . 
 we report a patient with a large cell neuroendocrine carcinoma of the kidney , who underwent radical resection and is doing well on follow - up . 
 the diagnosis was confirmed by immune - histochemistry .