Introduction: Increasing availability and sensitivity of ultrasound has led to burgeoning identification of small, non-palpable, intratesticular lesions. While the overall rate of malignancy of testicular lesions is high at 80–90%, for non-palpable lesions, the rate is much lower at 20%. Limited data exist regarding the natural history and malignant potential of small testicular masses.

Methods: We retrospectively reviewed all scrotal ultrasounds performed at the University Health Network in Toronto, Canada, between July 1996 and July 2015. In total, 2978 ultrasound reports met criteria and were reviewed manually. Patients were included in the final cohort if they had a non-cystic single or multifocal mass-like lesion(s) no larger than 1 cm. Long-term followup was conducted by cross-referencing with provincial health information system Cancer Care Ontario data of all orchiectomies with a diagnosis of testis cancer with a minimum two-year followup period.

Results: In total, 116 met inclusion criteria, of whom only 15 (12.9%) were found to have testis cancer. Twenty-five (21.6%) underwent orchiectomy for clinical concern of testis cancer. Of those undergoing orchiectomy, 11 (42%) were benign and 14 (58%) were malignant. One patient was diagnosed on retroperitoneal biopsy. Several factors were associated with finding testis cancer at orchiectomy, including younger median age (29.98 vs. 50.83 years, p=0.0001), prior history of contralateral testis cancer (87% vs. 2%, p<0.001), larger lesion size (6 mm vs. 4 mm, p=0.0015), multifocality (47% vs. 17%, p=0.0144), calcifications within the lesion (33.3% vs. 3.96%, p=0.0017), and calcifications in the testicle in general (46.7% vs. 11.9%, p=0.003).

Conclusions: Our findings underscore that most small lesions are benign and reflexive; immediate radical orchiectomy may be overtreatment. In select men, particularly in the absence of the above-noted risk factors, surveillance and/or partial orchiectomy is warranted.