Microphallus (micropenis) refers to a smaller than normal penile length.
Definition: The length of the stretched penile length more than 2.5 standard deviations below the mean (< - 2.5 SD).
Conditions associated with congenital microphallus:
(1) pituitary disorder
(1a) hypogonadotropic (low production of LH, FSH)
(1b) isolated growth hormone deficiency
(2) LH-receptor defect
(3) defect in testosterone biosynthesis (17-beta hydroxysteroid dehydrogenase deficiency)
(4) defect in peripheral androgen action
(4a) 5-alpha reductase deficiency
(4b) partial androgen insensitivity syndrome
(5) genetic syndrome (Prader-Willi, Klinefelter, Noonan, other)
(6) testicular dysgenesis or anorchia
(7) in utero exposure to estrogen-based fertility drugs
Conditions associated with acquired microphallus:
(1) trauma or surgery
(2) low levels of testosterone (castration, etc)
(3) drug blocking testosterone effect
Differential diagnosis:
(1) buried penis
(2) misperception
