Brain Metastasis as the Initial Presentation of Carcinoid Tumor: Case Report and Literature Review

Neuroendocrine neoplasms of the lung include neuroendocrine carcinomas and neuroendocrine tumors (NETs). NETs are also known as carcinoid tumors (CaTs), which are categorized as typical carcinoid and atypical carcinoid (AC). Pulmonary CaTs often metastasize to various sites, including regional lymph nodes, lungs, liver, and bone; however, metastasis to the brain is relatively rare. It is even rarer for patients with CaTs to present with signs of brain metastasis initially. We report the case of a 50-year-old female patient who initially presented with neurological symptoms and magnetic resonance imaging findings suggestive of multiple sclerosis. Despite initial treatment for multiple sclerosis, further evaluation uncovered a rare case of bronchopulmonary AC tumor metastasis to the brain. This case highlights the importance of considering metastatic disease in patients presenting with atypical neurological symptoms, especially when initial management fails to yield expected outcomes. Our literature review revealed 7 cases of CaTs initially presenting with brain metastases, with our patient being the youngest among all published cases.