This singular case is one that will surely be regarded as exceptional. J.R. Harding writing in Journal of the Society of Medicine (89/101, 600) chronicles this unusual medical item of which a synopsis is to be found in The Psychologist Vol.28, No. 7.
The patient was male and aged 45. The procedure he underwent was to determine whether he had an undescended testicle. On computer investigation of the scrotum, the left testicle was found to be a simulacrum of an horrendous ghost screaming. Testicles with such Lovecraftian overtones are rare indeed. The formation, however, seems to have been entirely natural with no paranormal element: the shape into which the testicle had formed was quite coincidental.