Answer: Hamartoma

Histology: This well-demarcated nodule is composed of well-differentiated branching ductal epithelium without atypia. No islets of Langerhans are seen.

Discussion: Hamartomas of the pancreas are rare lesions. They can be solid or cystic, or both solid and cystic. This case was composed of well-demarcated focally cystic ductal structures embedded in hypocellular stroma. Islets of Langerhans are not seen. Hamartomas should be distinguished from adenocarcinomas; the latter would lack the well-defined architecture of a hamartoma.

Reference(s):
– Pauser U et al, Pancreatic solid and cystic hamartoma in adults: characterization of a new tumorous lesion. Am J Surg Pathol. 29:797-800, 2005.