A Rare Case of Hypoplastic Pancreas Presenting as Normal Lipase Pancreatitis

Abstract

Partial agenesis of the dorsal pancreas is a rare condition resulting in varying degrees of pancreatic body and tail hypoplasia. This embryologic underdevelopment is usually associated with reduced endocrine function and diabetes mellitus; in this case, however, we examine how this anomaly impacts pancreatic exocrine function, known to be concentrated in the affected area. We discuss the case of a 47 year old woman with history of diabetes who was seen in the ED complaining of two days of epigastric pain radiating to her left back, nausea, and vomiting. She denied history of NSAID use, alcohol ingestion, or gallstones. Initial vitals were normal, and examination was remarkable for left upper quadrant tenderness without rebound. The patient's presentation was suspicious for acute pancreatitis (AP), yet amylase and lipase levels were normal at 40 U/L (25-150 U/L) and 251 U/L (73-393 U/L), respectively. Serum calcium was also normal, however triglycerides (TG) were elevated at 537 mg / dL. Clinical suspicion for AP remained, and while abdominopelvic computed tomography (CT) did confirm marked inflammatory changes in the peripancreatic mesentery consistent with the diagnosis, it was also noteworthy for congenital absence of the pancreatic tail. Gallbladder ultrasound demonstrated no evidence of cholelithiasis, and cholescintigraphy confirmed patency of the common bile duct and hepatopancreatic ampulla. The patient was managed in the usual fashion without issue, and lipase remained normal throughout her one-week admission. Repeat CT scan two months later revealed a pancreatic pseudocyst and resolution of the previously noted inflammation. This is a rare case of clinical and radiographic normal-lipase pancreatitis (NLP). The estimated negative predictive value of this enzyme in diagnosing AP is 94-100%; in fact, less than ten cases of NLP are described in the English literature, none of which occur in the setting of partial agenesis of the dorsal pancreas. We propose that reduction in exocrine pancreatic mass due to this defect decreases measurable serum lipase. In fact, this abnormality may even predispose the patient to hypertriglyceride-associated pancreatitis (HTGP); while HTGP is generally involves TG levels over 1000 mg / dL, we theorize that TG levels in this case were sufficient to induce AP because of decreased available enzymatic activity. Thus, we believe this case establishes a link between total exocrine mass and the somewhat uncertain mechanism of HTGP.Figure 1