[citation needed] Due to excess testosterone secreted by the tumour, one-third of female patients present with a recent history of progressive masculinization.

Additional signs include acne and hirsutism, voice deepening, clitoromegaly, temporal hair recession, and an increase in musculature.

In adults, this causes a number of problems including gynaecomastia, erectile dysfunction, infertility, feminine hair distribution, gonadogenital atrophy, and a loss of libido.

Testicular Leydig cell tumours can be detected sonographically, ultrasound examinations may be ordered in the event of a palpable scrotal lump, however incidental identification of these lesions is also possible.

Immunohistochemical markers of Leydig cell tumours include inhibin-alpha, calretinin, and melan-A.

[6] The usual chemotherapy regimen has limited efficacy in tumours of this type, although imatinib has shown some promise.

[10] The prognosis is generally good as the tumour tends to grow slowly and usually is benign: 10% are malignant.