Mixed adenoneuroendocrine carcinoma (MANEC) as a rare case of the rectum

Abstract

Introduction: Mixed adenoneuroendocrine carcinoma (MANEC) is a rare tumor consist of two components, adenocarcinoma and neuroendocrine differentiation. Every each have to represents at least 30% of the tumor. Diagnosis is based on cytology, architecture and immunostaining. Specific neuroendocrine markers for MANEC are chromogranin A and synaptophysin. Purpose: In this paper, we aimed to present a case of MANEC arising from rectum. Case presentation: 67-years-old man was admitted to the hospital due to abdominal pain, obstruction and blood in the stool. From the colonoscopy simple, the histopathological examination exposed microfoci of adenocarcinoma. Small pelvis MRI disclosed clinically known circular, solid infiltrate in the middle and upper part of the rectum. Local advancement in MRI was T4b N2 EMVI + CRM +. Patient underwent the neoadjuvant radiochemo-therapy. The control MRI revealed tumor reduction. Local advancement in MRI was yT3d yN0 EMVI + CRM + RG3. The histopathological examination of the surgical material revealed MANEC tissue consisting of Adenocarcinoma G2 (60%) and Large cell neuroendocrinal carcinoma (40%) pT3 pN0 pMx. Immunohistochemical staining revealed a positive expression of chromogranin A, synaptophysin and Ki67 - 80% in the neuro-endocrine component. Lymphonodulitis reactiva 19/19. Seminal vesicles without neoplastic infiltration. The patient was discharged in good general condition, with a recommendation of a follow-up visit at a surgical clinic. Conclusions: MANEC is rare as a rectal neoplasm. Has no specific clinical symptoms. The most important in the diagnostic process is histopatho-logical analysis. Updating the knowledge about MANEC by new reports may optimize the diagnostic process, classification and treatment of this cancer.