Amyloidosis of the pancreas: histochemical differentiation between insular and extrainsular deposits.

The results of a study of eighty-two human pancreases affected by deposits of amyloid in the islets of Langerhans are presented. Two different types of amyloid deposits were observed, one affecting the exocrine tissue and the other affecting the islets. These deposits were found to be histochemically different and appeared to indicate two different aetiopathogenetic processes. The deposit found in the exocrine tissue is essentially perivascular and might be considered an extension to the pancreas of a systemic amyloidosis of the "senile type"; the islet deposits appear to be a completely different phenomenon that could become part of the biology and pathology peculiar to the so called APUD system. The coexistence of the two types of amyloid in the human pancreas would seem, therefore, to represent a casual event.