MRI findings of an atypical testicular epidermoid cyst: A case report.

Introduction: Typical testicular epidermoid cysts (TECs) manifestate as a target sign or onion skin sign on ultrasonography and magnetic resonance (MR) imaging. Clinicians are increasingly aware of the imaging characteristics of typical TECs, which allow accurate diagnosis and successful treatment while preserving the testicle, but atypical TECs are likely to be misdiagnosed as a malignant intratesticular neoplasm, leading to complete testicular resection. Patient concerns: A 26 year-old male patient complained of a painless enlargement of the left testicle that had been present for 1 month. The patient had no recent medical history of scrotal trauma or systemic infection. Diagnosis: A round 48 mm x 45 mm x 43 mm mass was seen inside the left testicle. T2-weighted images of the lesion showed a thin hypointense capsule. T1-weighted images of the lesion showed a hyperintense nodule on the cyst wall, which appeared hypointense on T2-weighted and SPAIR images. After Gd-DTPA injection, the lesion was not enhanced; however, the nodule was enhanced on THRIVE images. These manifestations were consistent with a benign intratesticular lesion, and MR imaging diagnosed atypical TEC, which was confirmed by pathology after surgery. Interventions: The patient was treated with organ-sparing surgery with testicular enucleation. Outcomes: The patient was re-examined with ultrasonography 3 months after surgery. The left residual testicular tissue appeared normal, and reproductive function was preserved. Conclusion: Urologists must be aware of the clinical and MR imaging characteristics of atypical TECs and the utility of preoperative MR imaging for the diagnosis of testicular lesions to ensure that organ-sparing surgery is performed rather than unnecessary orchiectomy.