Thymomas are slow-growing neoplasia arising from the epithelial cells of the thymus that usually present with respiratory symptoms, superior vena cava syndrome, or parathymic syndromes. Approximately 30% of thymomas develop myasthenia gravis. An additional 5% of patients with thymomas have other systemic syndromes, including rheumatoid arthritis, thyroiditis, red cell aplasia, systemic lupus erythematosus, and Cushing syndrome. Rarely, patients can present with diarrhea due to thymoma-associated autoimmune gastrointestinal pathologies that include Good syndrome (acquired hypogammaglobulinemia), thymoma- associated multiorgan autoimmunity, and autoimmune enteropathy. We present an uncommon and interesting case of an invasive metastatic thymoma with right upper lobe endobronchial lesion and autoimmune enteropathy in a 27-year-old female. The novelty of this case lay in the findings of extensive metastatic thymoma with right upper lobe endobronchial disease and autoimmune diarrhea.