Histological examination of the pancreas from a patient with long-standing type 2 diabetes mellitus shows amorphous pink hyaline material replacing many islets of Langerhans. Congo red stain is positive. The chemical nature of this deposit is:

• A Insulin aggregated into fibrils
• B Procalcitonin cleaved by beta cell proteases
• C Islet amyloid polypeptide (amylin) co-secreted with insulin by beta cells ✓
• D Amyloid A protein deposited from the circulation

Explanation

Islet amyloid polypeptide (amylin) is a 37 amino acid peptide co-secreted with insulin from beta cell granules and is the precursor of the islet amyloid seen in type 2 diabetes, where it contributes to progressive beta cell loss. Calcitonin-derived prohormone produces amyloid in medullary carcinoma of the thyroid, not the islets, and serum amyloid A is restricted to reactive systemic amyloidosis.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.