Lipase hypersecretion syndrome (LHS) is a
paraneoplastic syndrome seen exclusively as a result of pancreatic
acinar cell carcinoma (ACC). In LHS, acinar
enzymes (
lipase,
trypsin and
chymotrypsin) which are normally secreted to the duodenum for digestive purposes, are instead released to the blood by the
carcinoma cells. In a way, it is "endocrine-ization" of an "exocrine" function. These circulating
enzymes, especially
lipase, exerts its digestive action on other tissues, especially on the subcutaneous tissues in the pressure poins of legs, creating a picture often mistaken as
erythema nodosum or
rheumatic nodules. The bone and joints may also be effected, which mostly appears to be secondary to the complications and super-
infection of the skin lesions.
Eosinophilia also often accompanies this syndrome. The accurate diagnosis of LHS requires the identification of the pancreatic primary as well as its correct classification as acinar because a variety of pancreatic
tumors can be associated with skin lesions, ranging from rare
metastasis of
adenocarcinoma to the
necrolytic migratory erythema caused by
glucagon-producing
neuroendocrine tumors. Towards this differential, the diagnostic characteristics of
acinar cell carcinomas that have been better elucidated in the past decade often need to be employed in increasingly smaller specimens and the liver, especially since most LHS cases also have liver
metastasis (presumably due to the by-pass of the "first-pass" liver metabolism phenomenon). ACC (and LHS) occur in patients in their 60's. The pancreatic mass is often large, round, demarcated and closely resemble neuroendocrine and solid-pseudopapillary
neoplasms but are more atypical/proliferative, and commonly show single prominent nucleoli and a distinctive chromophilia. Immunostaining with
trypsin/
chymotrypsin, negativity of
beta-catenin help in the differential; as a caveat, neuroendocrine differentiation is common in ACCs. In conclusion, LHS is a rare type of
paraneoplastic syndrome specific to ACC. The accurate diagnosis requires attention to their subtle diagnostic characteristics.