Müllerian-type serous cystadenomas of the testis/paratestis are rare benign epithelial neoplasms that resemble ovarian serous cystadenomas. We present a case of a 59-year-old man who presented with a 15-kilogram weight loss and a right groin lump with history of undescended testis. He underwent a right orchidectomy. Histology showed multilocular cystic lesion with fibrous septa and lined with ciliated epithelium with bland nuclei. There was no evidence of atypia or mitotic figures. Epithelial lining was diffusely positive for PAX8 and WT1 suggesting Müllerian origin. There were also marked testicular atrophy and complete loss of spermatogenesis. To our knowledge, there are no reported cases of Müllerian-type serous cystadenomas associated with cryptorchidism. The origin of these tumours and their distinction from clinically aggressive neoplasms are discussed. Presumed origins include Müllerian remnants or Müllerian metaplasia of tunica vaginalis.
Banal et al. (Sun,) studied this question.