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Leydig cell tumor of the testis

Last revised by Dr Joshua Yap on 25 Jul 2022

A Leydig cell tumor of the testis is an uncommon testicular neoplasm. Its imaging appearance on ultrasound and MRI is nonspecific, but clinically it is associated with serum hormonal imbalance.

1-3% of all testicular tumors, but the most common sex-cord stromal tumor. Tend to be bimodal, with one peak occurring in pediatric patients (5-10 years) and one in adults (20-30 years).  Malignancy occurs in ~10% of tumors.

Leydig cell tumors arise from the interstitial cells of Leydig adjacent to the seminiferous tubules. They are characterized by the presence of intracytoplasmic Reinke crystals 3.

Leydig cell tumors of the testis may present with serum hormonal imbalance (~30%). Virilization (including precocious puberty) may occur. Hyperestrogenism may also occur and patients may demonstrate gynecomastia.

Malignancy cannot be excluded on imaging.

  • small, hypoechoic, round intratesticular mass
  • may demonstrate cystic areas
  • most often unilateral
  • difficult to differentiate from other testicular tumors

On an imaging differential, consider:

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Cases and figures

  • Case 1: on ultrasound
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