A Leydig cell tumor is an uncommon type of growth that most often develops in the testicles, or testes. It gets its name because it develops from cells known as Leydig cells, which normally produce testosterone inside the testes. Most Leydig cell tumors are benign, or non-cancerous, but in around ten percent of cases they are malignant, or cancerous. A Leydig cell tumor often produces hormones which can cause the development of feminine or masculine characteristics, depending on the specific hormone secreted. Occasionally, Leydig cell tumors may develop in women, from Leydig cells inside the ovaries.
Most tumors in the testes arise from what are called germ cells, the cells from which sperm develop. Tumors originate in non-germ cells in only around five percent of cases. A Leydig cell tumor is an example of a non-germ cell tumor. It is also an interstitial cell tumor, because the Leydig cells make up what is known as the interstitial tissue which lies between the seminiferous tubules, the tubes where sperm are created.
Other tumors from non-germ cells found in the testes include the Sertoli cell tumor, which develops from Sertoli cells in the seminiferous tubules, and the Sertoli-Leydig cell tumor, which contains a mixture of the two cell types. Leydig and Sertoli cells are also found in women. Here they may give rise to gynecological cancer of the ovaries.
Leydig cell tumors are usually discovered in men, and the cause is unknown. There may be no symptoms, but sometimes a Leydig cell tumor may cause a painless lump which is large enough to feel. If tumors secrete excessive amounts of male hormones, this can give rise to what are known as androgen-dependent syndromes, causing early puberty in boys and masculinization in women. Sometimes, female hormones may be produced by a Leydig cell tumor, leading to physical changes such as breast enlargement in males. Occasionally, the testis may feel painful or uncomfortable.
The treatment of a Leydig cell tumor will vary depending on whether it is malignant or not. A benign tumor may sometimes be surgically extracted without removing the testis. Malignant tumors are testicular cancer and, as is the case with other types of cancer, the treatment and outlook depends on how far the disease has spread. Surgery and chemotherapy are the main treatment options and the testis and nearby lymph nodes may have to be removed. For people with benign tumors the outlook is typically positive.