E2546. The Empty Scrotum in Adults: Diagnosis and Imaging Features of Complications in Adult Cryptorchidism
  1. Hannah Fleming; University Health Network
  2. Ciara O'Brien; University Health Network
  3. Andrew Nanapragasam; University Health Network
Cryptorchidism, defined as undescended testis into the scrotum, affects 1–5% of term and 1- 45% of premature infants. Albeit rare, Cryptorchidism can also present in the adult population. This is often picked up incidentally on imaging. In the absence of a known provided history, the undescended testicle can often be mistaken for an alternate pathology such as an abnormal lymph node or neoplasm. Evaluation and management of undescended testes in adults is controversial with only a few case reports in the literature. Only 1% of infants with cryptorchidism reach adulthood without treatment. The most common location is the inguinal canal but rarely it is found intra-abdominally (IA). If left untreated, 10% of IA testes will grow and become a mass. Case reports have described cases of men in their 40's with unilateral cryptorchidism not noticeable until they felt a heavy, palpable abdominal mass. The purpose: review the epidemiology of Cryptorchidism in the adult population, discuss clinical examination findings and mode of presentation, summarise the various locations of an undescended testicle, outline how to confirm an undescended testicle through imaging localisation techniques, review imaging features of the undescended testes in adulthood on CT, MRI and US, review imaging features of various complications of undescended testes such as torsion and malignancy.

Educational Goals / Teaching Points
Most (80%) undescended testes are palpable in the inguinal canal. The remainder (20%) are non palpable; of which 50% have an intra- abdominal location and 50% are atrophic or absent. Complications (torsion), Malignancy (IA testes have the highest malignant potential [35-40 times higher], risk increases with more proximal location due to a higher temperature, seminomas are the most common neoplasms. Carcinoma in situ is also common, the risk of torsion is often due to increased testicular volume caused by the neoplastic process, atrophic testicles can be misinterpreted as peritoneal metastases or lymph nodes). Infertility. Trauma (especially if superficially located).

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Pertinent Imaging Features include CT (hypoattenuating and can be difficult to differentiate from lymph nodes or small cystic structures), MR (hyperintense on T2W, DWI - shows marked hyperintensity which helps differentiate from lymph nodes and surrounding structures, contrast - better for visualisation and testicular enhancement. Can also be indicative of testicular viability). Ultrasound (usually insensitive at localising an undescended IA testes in adulthood). Localisation tips (follow the course of the spermatic cord, following the testicular vein, MRI - higher sensitivity (90%) and specificity (100%) compared to US for localisation, pre- and postcontrast Coronal T1w is the most sensitive for differentiating the Gubernaculum, Testes and Spermatic cord).

Familiarity with MRI and CT features of adult undescended testes can guide management, diagnose complications, avoid misdiagnosis e.g. misinterpreted as a primary intra-abdominal mass, metastases or appendicitis in the setting of acute abdominal pain.