Introduction:
Choledochoduodenal fistulas (CDF) are an uncommon and complex clinical entity, characterised by an abnormal communication between the common bile duct and duodenum. These fistulas may arise from a number of underlying conditions, including chronic inflammatory pathologies, peptic ulcer disease, malignancies, and trauma (1). Whilst there are documented cases of CDF arising from diffuse large B-cell lymphoma (DLBCL) of the duodenum following initiation of systemic chemotherapy, their occurrence secondary to non-Hodgkin’s lymphoma of the pancreas is an exceedingly rare phenomenon, with no previously documented cases in the literature (2).
Despite the myriad of causes of CDF, their occurrence secondary to non-Hodgkin’s lymphoma of the pancreas is exceptionally rare. Non-Hodgkin’s lymphomas encompass a diverse group of haematological malignancies characterised by the histological absence of Reed-Sternberg cells. Most originate from B-cell lines, with DLBCL being the most prevalent subtype (3). Since the 1970s, the incidence of non-Hodgkin’s lymphoma has doubled, affecting one in ten-thousand individuals. While 75% of patients present with nodal disease, 25% may exhibit extra-nodal disease, involving the skin, oropharynx, gastrointestinal tract, bone, central nervous system and lungs. The pancreas, however, remains an exceptionally uncommon site of primary lymphoma formation, accounting for only 1% of extranodal lymphomas and 0.5% of all pancreatic tumours (4).
High grade lymphomas such as DLBCL are typically more aggressive than their low grade counterparts, but are often more amenable to curative treatment. They are characterised by rapidly enlarging lymphadenopathy and systemic symptoms such as fever, nocturnal diaphoresis and weight loss. Conversely, pancreatic lymphomas tend to display a more insidious onset with non-specific symptoms, hence complicating the diagnostic process (3). The formation of CDF in this context represents an extremely rare and late-stage manifestation, underscoring the intricate interplay between lymphomatous infiltration, local tissue destruction and subsequent fistula formation. These fistulas demonstrate the potential for serious complications, including biliary obstruction, cholangitis and sepsis.
This case report elucidates the clinical course of a patient with CDF arising secondary to pancreatic DLBCL, as well as the diagnostic and managemental challenges encountered. The rarity of this complication of pancreatic DLBCL is underscored by the apparent absence of documented cases in the existing literature. Moreover, this report seeks to contribute to the growing body of knowledge surrounding the complex interplay between lymphoproliferative disorders and gastrointestinal complications, emphasising the importance of clinical vigilance in patients presenting with atypical symptoms.