Introduction: Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors arising from cells that are part of the diffuse neuroendocrine system.
Patients, materials and methods: We conducted a retrospective study in which we included a number of 91 cases diagnosed with neuroendocrine tumors (NETs). Descriptive statistics was performed: number of cases based on location, distribution by gender (male∕female), distribution by age, and we also performed a morphological and immunohistochemical (IHC) study.
Results: The highest number of cases was found in lungs (60 cases). Tumors located on the skin, breast or bladder have been discovered, locations considered rare for this type of tumor. Of all cases diagnosed in the lungs, 59 were diagnosed as small cell carcinomas (SCCs) and only one case as NET. All surgical specimens were positive for chromogranin A (CgA), with a different expression for the other immunomarkers. For the lung biopsies, the most frequently IHC staining was CgA and cluster of differentiation 56 (CD56), with an increased positivity for the latter.
Conclusions: CgA remains the most sensitive immunomarker in the diagnosis of NETs. CD56 is the most widely used immunomarker for diagnosing small cell lung tumors. Positive expression of thyroid transcription factor 1 (TTF1) immunomarker does not confirm pulmonary origin of SCCs.