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40. What are the unique features of precocious puberty associated with primary
    hypothyroidism?
    The unique features of precocious puberty associated with primary hypothy-
    roidism include decreased growth velocity, absent/sparse pubic hair, and
    delayed bone age. Boys with precocious puberty associated with primary
    hypothyroidism have testicular enlargement without reactivation of HPG-axis,
    while the girls usually present with menarche and inappropriate progression of
    secondary sexual characteristics, e.g., menarche at Tanner breast stage 2. In
    addition, girls may also have galactorrhoea and multicystic ovaries. Absent/
    sparse pubic hair despite testicular enlargement is due to prepubertal levels of
    testosterone in boys and deleterious effect of decreased levels of thyroxine on
    pilosebaceous unit. Despite raised levels of gonadotropins (FSH), LH response
    to GnRH is prepubertal (GIPP) (Fig. 6.9).


41. A 2-year-old girl presented with breast development (B2) and one episode of
    vaginal bleed. Her MR imaging showed a sellar mass. What is the likely
    diagnosis?
    Precocious puberty in a child with a sellar mass is almost always due to primary
    hypothyroidism, as patients with sellar mass usually have delayed puberty,

ab

Fig. 6.9 (a) A 12-year-old boy with overt features of primary hypothyroidism. (b) Bilateral tes-
ticular enlargement without pubic hair

6 Precocious Puberty