Gastrointestinal pathology in Good's syndrome, thinking beyond common variable immunodeficiency: a clinicopathological observation.

Good's syndrome (GS) is a rare immunodeficiency associated with thymoma, characterized by increased susceptibility to bacterial, viral, and fungal infections, along with autoimmune manifestations. Gastrointestinal symptoms are common in GS, yet its clinical and histopathological features remain underrecognized. Due to significant overlap in clinical presentation and immunological profiles, GS is frequently misdiagnosed as common variable immunodeficiency (CVID). While gastrointestinal pathology in CVID has been well-documented, data on gastrointestinal manifestations in GS are limited. In this study, we analyzed two cases of GS, both demonstrating marked reduction of plasma cells across multiple gastrointestinal sites, with variable intraepithelial lymphocytosis and mild to moderate villous blunting in the duodenum and features secondary to chronic norovirus infection in one case, and an invasive adenocarcinoma with notable depletion of lamina propria plasma cells in the other. Accurate recognition of GS is essential for pathologists and clinicians, given its poorer prognosis compared to CVID.