Sex differences in immunohistochemical expression and capillary density in pancreatic solid pseudopapillary neoplasm

Solid pseudopapillary neoplasm (SPN) is a rare and low-grade malignant pancreatic neoplasm. Solid pseudopapillary neoplasm is rare in men, and most SPN cases are in young women. This study aimed to investigate sex differences in SPN clinical histopathology including capillary density and expression of immunochemical markers, including glypican 3. A total of 22 resected tumors from pancreatic SPN patients, including 16 women (73%) and 6 men (27%), were analyzed histopathologically and immunohistochemically for synaptophysin, β-catenin, estrogen receptor, progesterone receptor, Ki-67, CD10, CD31, and glypican 3. The median age was 52.5 years in men and 24 years in women (P = .046). The median tumor size was 22.5 mm in men and 40 mm in women (P = .337). In 11 of the 16 women (69%), but in none of the men, tumors showed complete or incomplete fibrous cap`sules (P = .006). Cholesterol clefts were observed in tumors from 10 women (63%) but in none from the men (P = .012). No significant sex differences were noted in tumor characteristics, including size, macroscopic cystic degeneration, necrosis, lymphovascular involvement, and perineural invasion. The SPNs were weakly positive for glypican 3, although there was no significant difference between sexes. Capillary density tended to be lower in tumors from men than in those from women, but not significantly. Thus, except for the fibrous capsule and cholesterol clefts often found in tumors and the younger age of the women, there were no significant sex differences in histopathologic or immunohistochemical features of SPN, despite its markedly higher occurrence in women.