TUNIC ALBUGINEA CYST

Ultrasonography is the modality of choice for characterization of palpable testicular lesions. Extratesticular lesions are more common than intratesticular ones and more than 95% of intratesticular lesions are malignant [­1].

At present, with the improvement in the resolution of sonography and of small-parts transducer, testicular cysts are reported more often, with an incidence between 4% and 10% of testicular sonographic explorations. [3, 4]

Nonneoplastic cystic lesions represent a subset of intratesticular lesions of which the majority are benign. It is important for the practicing radiologist and sonographer to recognize this benign subset to prevent unnecessary surgical exploration [2].

Relevant anatomic characteristics at US are important for understanding the origin and anatomic location of benign testicular cystic lesions. The tunica vaginalis, a fascial structure that envelopes the testicle, has a closely applied visceral layer and an outer parietal layer. The tunica albuginea, a fibrous layer deep to the tunica vaginalis, closely invests the testicle. The posterior surface of the tunica albuginea extends into the interior gland, forming an incomplete septum known as the mediastinum testis [2].The tunica albuginea can be seen as a thin echogenic line around the testis [5].

Cyst of the tunica albuginea are most commonly incidental findings but patients may present with pain, swelling and a firm pinhead sized mass [6].

The pathogenesis of tunica albuginea cyst is not known but believed to be mesothelial [2]. They are often associated with a history of trauma, hemorrhage and infection [8]. The cyst range from 2 to 5 mm in diameter and are brought to medical attention when a patient presents himself a palpable lump [2].The mean age at presentation is 40 years, and cyst can even be seen in the 5th and 6th decades [2].

At US, tunica albuginea cyst meet all the criteria of a simple cyst. They characteristically are located at the upper anterior or lateral aspect of the testicle. They can be uni – or multilocular. Sometimes the differentiation of a tunica albuginea cyst from a intratesticular simple cyst or a tunica vaginalis cyst is difficult [2].

Cyst may display low level echoes, a less common finding indicative of debris, or calcifications with acoustic shadowing [9].At microscopic analysis they are lined by nonciliated cuboidal cells, and they contain serous fluid and cellular debris [9].

Martinez – Berganza MT, et al [7]conclude that in patients with an extratesticular nodule smaller than 1 cm, with cystic echogenicity and a thin wall and situated in the upper anterior or lateral zone of the tunica albuginea the surgery can be avoided and follow up sonographic studies should be performed.