Ectopic epididymal tissue in appendix testis.

Aberrant epididymal tissue is uncommon and may be associated with an undescended testis. To the best of our knowledge, aberrant epididymal tissue has not been described in a testicular appendix. We report the case of a 7-year-old boy with left cryptorchidism who underwent a homolateral orchidopexy. At operation, the surgeon removed a pedunculated appendix testis containing an epididymal heterotopia. This Wolffian-derivative tissue was confirmed by the diffuse strong CD10 reactivity of the luminal border of the epithelial cells. Awareness of this aberrant tissue avoids misinterpretation as a transected functional reproductive structure.