Atypical intermediate-grade mediastinal carcinoid. Case presentation.

Background: Approximately 25% of carcinoid tumors develop in the respiratory system. Neuroendocrine carcinoids represent ~5% of all mediastinal tumors and 1-5% of all intrathoracic neoplasms. They contain numerous neurosecretory granules that synthesize, store and release neurohumoral substances that can induce the carcinoid syndrome.