Investigating the Link Between Abdominal Pain, Weight Loss, and IgG4-Related Pancreatitis: A Case Report.

This case report describes a 55-year-old male who presented with a two-year history of abdominal pain and weight loss, along with recent onset nausea, vomiting, and anorexia. Laboratory tests revealed elevated serum IgG4 levels and anemia, and abdominal CT showed diffuse pancreatic enlargement and multiple retroperitoneal lymphadenopathy. Endoscopic ultrasound-guided fine-needle aspiration of the pancreatic mass revealed dense lymphoplasmacytic infiltration with fibrosis and increased numbers of IgG4-positive plasma cells, consistent with the diagnosis of IgG4-related pancreatitis. Treatment with prednisone led to a significant improvement in the patient's symptoms and laboratory values, with subsequent reduction in the size of the pancreatic mass and retroperitoneal lymphadenopathy. The patient remained asymptomatic at the six-month follow-up visit, and serum IgG4 levels remained within the normal range. This case highlights the importance of considering IgG4-related disease (IgG4-RD) in patients presenting with abdominal pain and weight loss and the potential effectiveness of corticosteroid therapy in managing this condition.