[Enkephalin-like immunoreactivity in Leydig cell tumor].

So far, the presence of an enkephalin-like immunoreactivity has never been reported in Leydig cell tumors at our knowledge. A 39 years old man having a painful gynecomastia and an impotency changing in time has been studied. At clinical examination, he was normal, without palpable testis tumor. The sperm count analysis showed an oligoastheno-spermia. Plasma testosterone (T) was low and plasma estradiol (E2) was high, varying from day to day. T/E2 ratio was always low (20 to 72 - N:220-240) and fell after HCG administration. Plasma LH was normal and plasma FSH was low. 17 hydroxyprogesterone (17 OH-P)/T ratio was increased (0.7 - N:0.23). A small tumor was localized in the left testis by ultrasonography. The spermatic vein catheterization, which was only possible on the left side, showed a decreased T, a high E2 and a low T/E2 ratio (19 - N:304). After unilateral orchidectomy, the histological study confirmed the diagnosis of Leydig cell tumor. With antibodies raised against synthetic Met-en-kephalin, it has been possible to detect an enkephalin-like immunoreactivity in the tumoral cells as well as in the surrounding normal cells.