We herein report an unusual case of Erdheim-Chester disease (ECD), a rare non-Langerhans cell histiocytosis, and emphasize its unique presentation and diagnostic challenges. Our patient exhibited uncommon symptoms and significant organ involvement, particularly pancreatic enlargement that is not typically associated with ECD. Contrast-enhanced harmonic endoscopic ultrasonography (CEH-EUS) and EUS-fine needle aspiration (EUS-FNA) play crucial roles in the comprehensive assessment of the disease, demonstrating their superiority in identifying and characterizing elusive ECD lesions. This is the first report to document pancreatic lesions in patients with ECD evaluated using CEH-EUS. EUS-FNA is valuable for diagnosing rare diseases, including ECD, with diffuse pancreatic enlargement.

Insulin autoimmune syndrome (IAS) is a rare disorder characterised by autoantibodies against endogenous insulin that cause spontaneous hypoglycemic episodes. Here, we present the case of a 66-year-old male with polyarticular pain and dizziness that was initially suspected to be an insulinoma. However, further testing confirmed the presence of IAS. The patient\'s joint pain fluctuated but improved with the control of blood glucose levels. Although the direct relationship between IAS and joint pain is not well established, individuals with a single autoimmune disorder may develop concurrent autoimmune conditions. Joint pain is prevalent in patients with autoimmune diseases. Although hypoglycemia may cause muscle cramps due to stress responses, direct musculoskeletal damage is uncommon. This case underscores the importance of differential diagnosis, particularly in differentiating between pancreatic cancer and the benign proliferation of pancreatic B cells. Elevated levels of insulin autoantibodies confirm IAS, whereas pancreatic cancer may manifest various symptoms and elevated cancer antigens (CA) 19-9. General physicians should comprehensively investigate hypoglycemia cases, particularly those associated with pancreatic enlargement, and continually monitor for potential malignancies.

Epoprostenol is a prostacyclin (prostaglandin I2) analog that causes vasodilation and inhibits platelet aggregation and is used in the management of severe pulmonary arterial hypertension (PAH). We herein report a patient with PAH who developed pancreatic enlargement after the initiation of therapy including epoprostenol. Although it is well known that thyroid enlargement occurs in patients with PAH receiving epoprostenol therapy, the pancreatic findings associated with epoprostenol therapy have not been well described. Although the size of the pancreas was clearly increased, there was no blood data or symptoms suggestive of abnormal pancreatic function and pancreatitis, and the patient\'s abdominal complaints improved quickly, despite the continuation of epoprostenol therapy. Eleven months after the start of continuous intravenous epoprostenol infusion therapy, the pancreatic enlargement was still evident on imaging, but there were no abdominal symptoms or elevated pancreatic enzymes. This case highlights the fact that epoprostenol therapy may cause pancreatic changes that mimic acute or autoimmune pancreatitis.