paratesticular lesions include hydroceles , spermatoceles , cystadenomas , varicoceles , hernias , and fibrous pseudotumors . intratesticular lesions include testicular simple cysts , tunica albuginea cysts , epidermoid cysts , cystic ectasia of rete testis , intratesticular varicocele , adrenal rests , and splenogonadal fusion . rk is a 58-year - old man who was referred by his general practitioner to the urology out patient clinic because of a left scrotal swelling and pain for one - year . however , his job involves carrying and loading cartons of tea in a warehouse . on examination , he was a fit looking middle - aged man . the report of the ultrasound scan stated that both testes were normal , with the presence of a left hydrocele about 8 cm x 6.5 cm x 4 cm . intraoperatively , on opening the tunica vaginalis , we found a cystic swelling arising from the anterior mid part of the left testis . it looked like a cyst of the epididymis , but it was not related to it or the testicular vessels . the cyst was dissected away from the visceral lining of tunica vaginalis and excised at the base , leaving a rim of tunica albuginea of about 3 mm . the base of the cyst was about 1.5 cm , uneven and with scanty veins . histology of the sac was reported as a thin walled cyst measuring 6.5 cm x 3 cm x 1 cm . further review of the ultrasound by the radiologist revealed that the site where the cyst was attached to the tunica albuginea had a pattern of hyperechogenicity unlike other parts of tunica albuginea ( fig . in addition , there was a crescentic shadow at the lower pole where the wall of the cyst with the attached visceral layer of tunica vaginalis separated away from the parietal lining of tunica vaginalis with a trivial amount of fluid noticed at that angle ( figs . ultrasound picture showing the hyperechoic area at the base of the cyst and a faint crescentic line depicting the wall of the cyst . ultrasound picture showing the cyst wall reflection near the lower pole of the left testis . most studies and case reports classify cyst of the tunica albuginea as intra - testicular , because they point towards the parenchyma of the testis . however , there are very few reported cases of tiny tunica albuginea cysts arising from the external surface of the tunica albuginea [ 24 ] . our patient had a large tunica albuginea cyst arising from the external surface of tunica albuginea and presenting as a paratesticular cyst , looking almost like a hydrocele . the etiology of tunica albuginea cysts is unknown , but they are thought to be associated with trauma , hemorrhage , and infection . our patient told us that the cartons of tea he carries at the warehouse where he works often knock his testes . even though the wall of the cyst and attached visceral layer of tunica vaginalis were apposed to the parietal layer of tunica vaginalis , the fact that the scrotum was incised in layers helped us to separate them , otherwise if it was treated like a hydrocele it would have been a sure recipe for recurrence . this underscores the importance of following surgical principles even in minor operations . the crescentic shadow on the lower pole of the ultrasound scan image , where the parietal layer of tunica vaginalis separated from the visceral layer and the attached wall of the cyst ( figs . 2a , 2b ) could be a subtle feature to differentiate vaginal hydrocele from large cyst of the tunic albuginea .
a 58-year - old man presented with a large left scrotal swelling suspected to be a large hydrocele , both , clinically and on initial ultrasound . 
 however , at operation , a large tunica albuginea cyst was found arising from the mid anterior wall of the tunica albuginea . 
 it was dissected , excised and edges under run . 
 further review of the ultrasound scan revealed a unique feature of large tunica albuginea cyst simulating a hydrocele .