Composite epithelial kidney tumor comprising of adeno and neuroendocrine carcinomatous components: an unusual variant of renal cell carcinoma

Mixed Neuroendocrine-Nonneuroendocrine Neoplasms (MiNENs): Unifying the Concept of a Heterogeneous Group of Neoplasms

The wide application of immunohistochemistry to the study of tumors has led to the recognition that epithelial neoplasms composed of both a neuroendocrine and nonneuroendocrine component are not as rare as traditionally believed. It has been recommended that mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are classified as only those in which either component represents at least 30 % of the lesion but this cutoff has not been universally accepted. Moreover, since their pathogenetic and clinical features are still unclear, mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are not included as a separate clinicopathological entity in most WHO classifications, although they have been observed in virtually all organs. In the WHO classification of digestive tumors, mixed neuroendocrine-nonneuroendocrine neoplasm is considered a specific type and is defined as mixed adenoneuroendocrine carcinoma, a definition that has not been accepted for other organs. In fact, this term does not adequately convey the morphological and biological heterogeneity of digestive mixed neoplasms and has created some misunderstanding among both pathologists and clinicians. In the present study, we have reviewed the literature on mixed neuroendocrine-nonneuroendocrine epithelial neoplasms reported in the pituitary, thyroid, nasal cavity, larynx, lung, digestive system, urinary system, male and female genital organs, and skin to give the reader an overview of the most important clinicopathological features and morphological criteria for diagnosing each entity. We also propose to use the term "mixed neuroendocrine-nonneuroendocrine neoplasm (MiNEN)" to define and to unify the concept of this heterogeneous group of neoplasms, which show different characteristics mainly depending on the type of neuroendocrine and nonneuroendocrine components.

NEUROENDOCRINE RENAL CARCINOMA - THERAPEUTIC AND DIAGNOSTIC ISSUES

Introduction

Neuroendocrine renal carcinoma represents less than 1% of all primary neoplasia of the kidney. Most frequently poorly differentiated carcinoma is diagnosed in advanced stages and they have an aggressive evolution and limited survival rate. Neuroendocrine carcinomas that arise from the renal pelvis are frequently associated with squamous cell carcinoma or adenocarcinoma.

Material and method

We present the case of a female patient, known for 3 years before with an undefined retroperitoneal lymph node metastasis, being diagnosed at present with a left large cell neuroendocrine renal carcinoma, who initially had lymph node metastasis.

Results

Until now, 118 cases of primary neuroendocrine renal carcinomas have been reported. A limited number of poorly differentiated neuroendocrine carcinomas have been reported.

Discussion

Due to the clinical and biological findings, the aggressive evolution with early metastasis of lung and bone, the patient is included in the group of poorly differentiated carcinomas. In these cases, multimodal treatment is a gold standard. After surgical treatment and palliative chemotherapy with platinum salts, we obtained a partial remission of the disease and the control of symptoms.

Conclusions

Regarding large cell neuroendocrine carcinoma, the surgical treatment remains the treatment of choice. Chemotherapy can determine limited results, improve the quality of life and enhance the overall survival rate.