Endometriosis can rarely occur in a male. It may arise from a Mullerian remnant or metaplasia of mesothelial tissue.
Risk factors:
(1) hyperestrogenic state (cirrhosis, therapy of prostate cancer)
Locations may include:
(1) urinary bladder
(2) inguinal canal
(3) paratesticular mass
Clinical features:
(1) pain
(2) cystic lesion with hemorrhage
(3) endometrial-like glands and stroma
(4) absence of malignant histologic features
Immunohistochemical pattern for epithelial cells: positive for CK7, CA125 vimentin, and estrogen receptor (ER) while negative for CK20.
Differential diagnosis:
(1) teratoma
(2) transgender patient
(3) intersex
