Fig. 4

Macroscopic and microscopic findings of the resected specimen of the pancreas. a The resected specimen showed a hemispheric mass protruding from the pancreas tail and measuring 5.6 × 5.4 cm in diameter. b Solid components occupied most of this cystic mass. c, d Findings of the H&E staining. Oval and spindle-shaped cells proliferated bluntly with a richly vascular stroma, resembling the structure of hemangiopericytoma. Scale bars, 50 μm. e Immunohistochemical staining was irregularly positive for CD34, a mesenchymal marker. Scale bar, 100 μm. f Nuclear expression of STAT6 was diffusely positive in the immunohistochemical staining. Scale bar, 100 μm