[A cyst arising from tunica vaginalis testis : report of a case].

A 38-year-old man presented with left intrascrotal painless mass. Ultrasound and magnetic resonance imaging (MRI) examinations demonstrated a cystic lesion at the upper side of left testis without enhancement. This mass gradually enlarged in size, and left high orchiectomy was planned. Because intraoperative finding showed a cyst arising from tunica vaginalis testis, excision of the cyst was performed. Histopathological examination showed a cyst with a fibrous wall lined with cuboidal endothelial cells without malignancy. To our knowledge, this is the 15th reported case of a benign cystic lesion in tunica vaginalis testis in Japan. The age distribution of patients showed two peaks ; one from 5 to 8 years old and the other from 30 to 69 years old. Most of the pediatric patients showed acute scrotal swelling with pain. On the other hand, most adult patients demonstrated painless scrotal swelling with slow growth. Operative investigation should be performed in cases with suspicion of malignancy.