Novel insight for midline cyst formation in prostate: The involvement of decreased prenatal testosterone suggested by second-to-fourth digit ratio study.

ABSTRACT

OBJECTIVES: To clarify the relationship between midline cyst formation and second to fourth finger length ratio. METHODS: The present study included 95 benign prostatic hyperplasia patients and 61 healthy male college students. All midline cysts were identified by transrectal ultrasonography. In the benign prostatic hyperplasia group, 45 midline cyst (+) men (M(age) = 67.2 years) and age-matched 50 midline cyst (-) men (M(age) = 67.1 years) were included. In the university student group, 12 midline cyst (+) men (M(age) = 21.7 years) and age-matched 49 midline cyst (-) men (Mage = 21.1 years) were included. We took photocopies of the participants' bilateral hands, and measured the second and fourth finger length was measured by one examiner in a blind manner. RESULTS: Second to fourth finger length ratios in the benign prostatic hyperplasia group (right/left mean ± SD) were higher bilaterally in midline cyst (+) (0.95 ± 0.03/0.95 ± 0.03) than those in midline cyst (-) (0.92 ± 0.03/0.92 ± 0.03; P < 0.0001/P = 0.0010). Second to fourth finger length ratios in students were higher only in the right hand in midline cyst (+) (0.96 ± 0.03/0.94 ± 0.03) than those in midline cyst (-) (0.93 ± 0.03/0.94 ± 0.03; P = 0.0018/P = 0.9968). The second to fourth finger length ratio of midline cyst (+) men was significantly higher than that in midline cyst (-) men. CONCLUSIONS: The second to fourth finger length ratio is higher in subjects with midline cyst of the prostate. It can be speculated that the prostatic utricle dilates in cases less exposed to male hormones during fetal development.