Gender difference in the transabdominal ultrasound findings of solid-pseudopapillary neoplasm

Background: Solid-pseudopapillary neoplasm (SPN) is a rare tumour that is mostly observed in young females. However, onset in males is also observed, and they do not necessarily present with typical findings. A comparison between male and female SPN patients focusing on the ultrasound findings was performed. Methods: Sixteen patients including 5 males who received transabdominal ultrasounds and were diagnosed with SPN based on their resected specimens were compared by sex in terms of the following: 1) age, 2) symptoms, 3) ultrasound findings, 4) preoperative ultrasound diagnoses, and 5) histology. Results: 1) The age was significantly higher in males (43 vs. 31, P = 0.004). 2) Symptoms were not observed in any of the males while 4/11 females were symptomatic (P = 0.245). 3) Tumour size was significantly smaller in males (20 mm vs. 33 mm, P = 0.014), and there was a higher percentage of cystic components in females (0% vs. 73%, P = 0.026). 4) SPN was listed as the first differential diagnosis in 9/11 females as opposed to 2/5 males (P = 0.139). 5) Cystic areas on the ultrasound corresponded to necrosis and hemorrhage. All cases showed expression of progesterone and androgen receptors regardless of sex. Conclusions: There were significant differences between male and female SPN patients in terms of age, tumour size, and presence of cystic components. Attention should be paid to the finding that onset in males was more common from middle age onwards in comparison to females and that a cystic component was not observed.