CHRONIC INCREASED SERUM LIPASE WITHOUT EVIDENCE OF PANCREATITIS - TUMOR-DERIVED LIPASE

A 51-year-old man developed a large retroperitoneal tumor with liver a nd lymph node metastases; there was no radiological evidence of pancre atic involvement. Despite the progression of disease, results of labor atory tests, notably serum amylase, were normal except for minor incre ases in aspartate aminotransferase and gamma-glutamyltransferase and a marked increase in lipase, The increased lipase was not attributable to formation of macroenzyme. To determine the source of the lipase, we fractionated serum and a tumor biopsy homogenate, using electrophores is. The lipase pattern obtained from the patient's serum differed from that seen in serum from a patient with acute pancreatitis. Additional ly, the lipase pattern obtained from a homogenate of biopsy sample fro m the retroperitoneal tumor did not match the pattern observed for nor mal pancreas. Apparently, the source of this increased serum lipase ac tivity was the nonpancreatic tumor.