Gout represents a disease caused by uric acid deposition and is characterized by acute gouty arthritis, tophi formation, and uric acid nephrolithiasis. Tophi, deposits of sodium urate monohydrate crystals that usually occur in and around the joints, are rarely observed in patients without a history of gouty arthritis (1). Ectopic uric acid deposition, with tophi occurring in tissue other than periarticular, subcutaneous, or renal tissue, is extremely rare and has been found in the heart, spine, eye, and larynx (2, 3). We now report the first case of inflammatory tophaceous deposits within a pancreatic pseudocyst.
The patient, a 39-year-old Hispanic man, was transferred to our medical center for surgical drainage of an infected pancreatic pseudocyst. Five months before admission, he developed acute alcoholic pancreatitis, and 2 large pancreatic pseudocysts were found 2 months later. The patient had previously been healthy and was taking no medications. He denied any history of arthritis, kidney stones, gall stones, or neurologic impairment but reported that his grandfather had a history of gout. At the time of transfer, the patient had nausea, abdominal pain, and daily low-grade fever. He had been taking broad-spectrum antibiotics for 4 weeks prior to admission to the hospital. A helical computed tomography scan performed at the previous facility revealed a large (5 × 5 cm) pseudocyst with pockets of air in the body of the pancreas. Another large pseudocyst (7 × 5 cm) was visualized in the tail of the pancreas.
On admission to our hospital, physical examination revealed a well-developed, well-nourished man with normal vital signs. The abdomen was soft and nondistended. There was mild tenderness in the epigastric area, without rebound or guarding. Musculoskeletal examination revealed no tophi or synovitis.
The patient underwent surgical drainage and debridement of the infected pancreatic pseudocyst. Intraoperatively, a copious amount of milky-colored fluid was drained from the pseudocyst. The cyst also contained dense, cheesy, necrotic material. Pathologic examination of the necrotic material revealed fat necrosis and saponification, with aggregates of crystals (Figure 1A). Examination of the cystic fluid under polarized microscopy revealed abundant negatively birefringent needle-shaped crystals consistent with gout (Figure 1B). Biochemical analysis of the cystic fluid confirmed that it was uric acid. Complete blood cell count, renal function, and electrolyte levels were within normal limits. The patient had normal findings on thyroid function tests and no monoclonal gammopathy. Multiple blood cultures were negative. Laboratory studies of blood and 24-hour urine specimens were obtained after he had received total parenteral nutrition (TPN) for more than 3 days. His serum uric acid level was very low at 2 mg/dl (normal 3.8–8.9), whereas the urinary uric acid level was in the low-normal range at 261 mmoles/24 hours (normal 250–750). The quantity of uric acid in the urine was higher than expected in conjunction with a serum uric acid level of <2 mg/dl.
The patient continued to have nausea and epigastric pain, and repeat drainage and examination revealed abundant uric acid crystals. Based on these findings, therapy with uricosuric agent, sulfinpyrazone 200 mg orally twice a day, was started to determine whether a defect in tubular reabsorption of urate was causing his serum uric acid level to be low while the urinary level was normal. TPN was discontinued, and he resumed oral food intake. Seven days after initiation of sulfinpyrazone therapy, 24-hour urinary uric acid secretion increased to 612 mmoles, suggesting that reabsorption of uric acid by renal tubules was probably normal. His serum uric acid level also increased, to 3.7 mg/dl, despite sulfinpyrazone treatment. He has had no recurrence of pancreatitis or symptoms of gout during a followup period of 3 months.
We hypothesize that the following factors contributed to the gouty pseudocyst: 1) increased systemic uric acid production secondary to ethanol abuse, 2) a probable defect in renal tubular secretion of uric acid, and 3) possible increased uric acid production by the pancreas or pancreatic pseudocyst due to tissue ischemia associated with pancreatitis. It is likely that the numerous crystals present in the pseudocysts contributed to inflammation in that tissue. Therefore, it would be interesting to know if urate crystals could be identified in pancreatic pseudocysts of other patients, because introduction of urate-lowering therapies might be useful in preventing subsequent attacks of pancreatitis in such individuals.