Spermatic Cord Walthard Cyst as Inguinal Mass: CT/MRI and Immunohistochemical Correlation

Walthard cell nests are benign urothelial-like rests whose cystic transformation results in Walthard cysts. Their occurrence in male paratesticular structures is rare and can mimic urothelial or mesothelial disease.

An 85-year-old male with a history of left inguinal hernia repair presented with a 33-mm whitish cyst adherent to the hernia sac. Ultrasonography revealed a well-defined, hypoechoic mass without internal vascular flow. Non-contrast CT revealed a lobulated, hyperattenuating lesion (~196 HU); in contrast, MRI showed intermediate-to-slightly high T1 and low T2 signals without diffusion restriction, consistent with a protein-rich cyst. Intraoperatively, the cyst ruptured, releasing whitish turbid fluid, and was excised en bloc during mesh plug repair. Cytology revealed crystalline material without cells, and cultures were negative. Histologic examination showed a thin-walled fibrous cyst lined by multilayered transitional-type epithelium without atypia. Immunohistochemistry demonstrated positivity for CK5/6, CK7, GATA3, p63, and WT1; negativity for CK20, uroplakin III, PAX8, calretinin, and OCT3/4; and a Ki-67 index of <1%.

This case represents the 2nd full-length, peer-reviewed report of a spermatic cord/inguinal canal Walthard cyst of this size. Compared with previous reports, our case uniquely offers comprehensive CT/MRI correlation, a complete immunophenotypic profile-including WT1 positivity with CK20 and uroplakin III negativity-and precise size documentation, thereby aiding in the prevention of misdiagnosis and overtreatment of cystic lesions in the inguinal canal of males.