A unifying concept of chorionic gonadotrophin production in malignancy

Elevated blood levels of immunoreactive human chorionic gonadotrophin (HCG) have been reported in many patients with non-trophoblastic tumours, but also in various non-malignant conditions. Even normal tissues other than placenta have been shown to produce HCG, such as gonads, gastrointestinal tract, liver, and pituitary. Since HCG is produced, albeit at a low level, by a variety of normal tissues, there is no need to invoke the gene derepression theory to account for 'ectopic' HCG production. However, tumours associated with excess of biologically active HCG as evidenced by endocrinological abnormalities, such as precocious puberty or gynaecomastia, are very rare. We have reviewed the world literature and found 44 such tumours in the lung, adrenal gland, liver, gastrointestinal tract, and genitourinary tract (excluding the gonads). The analysis of their histological pattern shows that they typically contain syncytial giant cells or frankly choriocarcinomatous elements. In this respect they are like germ-cell tumours associated with excess HCG production. The precursor of the HCG-containing cells in 'somatic' tumours is unknown but their functional and morphological similarity to the trophoblast revives the old concept of pathophysiological correspondence between some malignant tumours and invasive trophoblast.