Human monorchism: a clinicopathological study of unilateral absent testes in 65 boys.

We reviewed the medical records of 65 boys with surgically and pathologically proved monorchism. A striking laterality to the left side was identified. In 83 per cent of the patients wolffian structures were present and in 20 per cent microscopic evidence of a terminal nubbin of hyalinized, calcified or hemosiderin-containing tissue was noted. These findings strongly suggest that in most instances of monorchism a testis had been present and had undergone subsequent in utero degeneration. Characterization of the hormonal changes associated with unilateral absent testes was done by determining fasting morning levels of luteinizing hormone and follicle-stimulating hormone. In a subgroup of monorchid boys and age-matched prepubertal unilateral cryptorchid boys luteinizing hormone release factor stimulation also was performed to determine if endocrine analysis could predict the absence of 1 testis.