Germ cells positive for PLAP and c-Kit in 11-16 year old normal boys with ongoing spermatogenesis

INTRODUCTION: Positive staining of testicular germ cells for PLAP and c-Kit beyond infancy may be associated with the presence of GCNIS (Germ Cell Neoplasia In Situ). We recently reported our findings of positive staining of normal, infantile germ cells for PLAP, and c-Kit up to 2 years of age, contrary to previous studies. The present study aims to elucidate whether otherwise normal testes of boys undergoing puberty express PLAP, c-Kit, Oct3/4, or D2-40.

MATERIALS AND METHODS: Biopsies were taken from 31 boys (11.5-16.5 years of age, mean and median of 13.5 years), who underwent surgery either for torsion of the testis (15) or a history suspicious of intermittent torsion of the testis (16). 21 were biopsied on both sides, making a total of 52 biopsies. Four testes were necrotic. The biopsies were fixed in Stieve's medium, cut into 2 μm sections, and mounted on coated slides. One slide was processed for H-E, and the others incubated with primary antibody for PLAP, c-Kit, D2-40, and Oct3/4.

RESULTS: 87% of the boys stained positive for both PLAP and c-Kit. None were positive for either D2-40 or Oct3/4. None had any histological features characteristic of GCNIS. Only two boys showed no signs of having initiated spermatogenesis. Those positive for PLAP were likewise for c-Kit, and vice versa, except 2; one boy, 13 years, was positive for PLAP, but negative for c-KIT, another, 16 years, was negative for PLAP and positive for c-Kit. Three boys stained positive for PLAP and c-Kit on the right side, and negative on the left. One boy was negative for c-Kit on the right side, positive on the left, and positive for PLAP bilaterally.

CONCLUSION: Positive staining of testicular germ cells for PLAP and c-Kit seems to be a normal finding in boys not having completed puberty. Rather than indicating pre-malignant transformation, the positivity is indicative of an ongoing maturational process of the germ cells.