Amenorrhea and Abnormalities of Puberty

Chapter 128


Amenorrhea and Abnormalities of Puberty



Indications for evaluation of the adolescent pelvis usually are reports of abdominal pain, pelvic pain, or a mass. Many of the differential diagnoses for these complaints have been reviewed in Chapter 127. Other clinical symptoms resulting in imaging evaluation in female patients relate to abnormalities of development of secondary sexual characteristics of puberty. These changes may be seen earlier than normal (i.e., precocious puberty), may be delayed (i.e., delayed puberty), or may fail to develop (e.g., hypogonadism and sexual infantilism) in adolescents. The other key reason for adolescent gynecologic evaluation is amenorrhea (lack of menses), whether primary or secondary. Conditions causing pubertal delay also may cause primary or secondary amenorrhea.1,2



Puberty


Puberty among girls is the stage of development in between childhood and adulthood when activation of the hypothalamic-pituitary-ovarian-uterine axis produces maturation of the gonads, resulting in an increased production of sex hormones, development of secondary sex characteristics, a growth spurt, and development of reproductive capability. The earliest signs of puberty among girls are breast development (usually occurring between ages 8 and 13 years) and pubic hair growth (at age 8 to 14 years). These signs are followed by a growth spurt (at age 9.5 to 14.5 years), axillary hair development, and menarche (at age 10 to 16 years). Puberty is usually completed within about 4 years.1,3,4


Puberty among boys begins between 9 and 14 years of age and is completed in 3.5 to 4 years. It begins with testicular enlargement (usually occurring between age 9 and 13.5 years), followed by the appearance of pubic hair (at age 10 to 15 years), enlargement of the penis (at age 11 to 12.5 years), and development of axillary and facial hair, as well as a growth spurt (at age 10.5 to 16 years).1,3



Physiologic Changes at Puberty and the Normal Ovulatory Menstrual Cycle


Ordinarily, until the age of at least 8 years, an unknown “central restraining mechanism” prevents the pulsatile release of gonadotropin-releasing hormone (GnRH) from the arcuate nucleus of the hypothalamus. Pulsatile release of GnRH appears necessary for ovulation and development of the corpus luteum. In early puberty the pulsatile GnRH release is maximal only at night, but with time the typical adult pattern of continuous pulsatile GnRH secretion develops.1,4,5


With the earliest activation of GnRH, most girls undergo ovarian folliculogenesis without ovulation. Unopposed estrogen production leads to progressive uterine growth and endometrial proliferation. Breast budding, physiologic leukorrhea, and accelerated linear growth occur. As the hypothalamic-pituitary-ovarian-uterine axis matures over approximately a 2-year span, cycles with subnormal progesterone production and shortened intermenstrual intervals are replaced by normal corpus luteum function and fertile cycles.1,4,5


The typical ovulatory cycle has a 24- to 35-day intermenstrual interval and usually a premenstrual molimina. Longer intervals often are associated with anovulation. Improved nutrition and living conditions are thought to be responsible for the gradual decrease in mean menarchal age during the past century. In North America, the mean menarchal age currently is 12.4 years with a range of 9 to 17 years. Menarche usually occurs 2 to 5 years after breast bud development.1,5



Premature Thelarche and Adrenarche





Overview and Clinical Presentation: Premature thelarche and adrenarche are relatively common, self-limited variants of normal pubertal development in girls. Premature thelarche refers to premature breast development without other signs of precocious sexual maturation in girls younger than 8 years of age. It usually is seen between 1 and 4 years of age. A third of the cases resolve spontaneously. Premature adrenarche refers to the appearance of pubic and axillary hair without other signs of precocious sexual maturity. In both premature thelarche and premature adrenarche, bone age and patient height are normal to only slightly increased. The cause of premature thelarche or adrenarche is not certain. The levels of circulating sex hormones usually are normal. Increased end-organ sensitivity to normal levels of estrogen or androgen has been suggested as a possible cause.1,6,7


In boys, premature appearance of pubic and axillary hair without other signs or only minor signs of precocious puberty is a relatively common variant of normal development that may be due to an increase in circulating androgens from premature maturation of the adrenal glands of unknown cause. No penile enlargement is present, presumably because the levels of circulating androgens are not sufficiently elevated. The bone age and growth rate are slightly increased. The remainder of pubertal development occurs at a normal age.1,7



Precocious Puberty


Precocious puberty refers to the appearance of secondary sex characteristics before 8 years of age in girls and before 9 years of age in boys. Precocious puberty is divided into two main types: (1) complete, central, gonadotropin-dependent, or true precocious puberty and (2) incomplete, peripheral, gonadotropin-independent, pseudoprecocious puberty, or precocious pseudopuberty. Whereas the complete form is characteristically isosexual, with development of secondary sex characteristics that are appropriate for the patient’s gender, the incomplete form may be either isosexual or heterosexual. Incomplete heterosexual precocious puberty is manifested by signs of virilization in girls and by gynecomastia or other signs of feminization in boys.1,6,7



Complete or Central Isosexual Precocious Puberty






Etiology and Imaging: The cause of precocious puberty in girls is idiopathic in at least 80% of cases. About 20% of affected girls have a hypothalamic or pituitary lesion. Fewer than 10% of cases of true precocious puberty in boys have an idiopathic cause. A familial tendency to idiopathic early pubertal development is observed in some cases (i.e., constitutional or genetic precocious puberty).1,8,9


Possible causes of precocious puberty in either sex include intracranial tumors or cysts, hydrocephalus, sequelae of intracranial inflammatory processes or trauma, and other intracranial lesions that may activate the hypothalamus by pressure or invasion. Of the CNS neoplasms that may cause true precocious puberty, hamartoma of the tuber cinereum (Fig. 128-1) is the most common. This usually small CNS tumor is more common in boys than in girls, is generally benign, and is nonprogressive. The hypothalamic hamartoma secretes GnRH, and the resultant symptoms usually cannot be corrected surgically. The onset of puberty in patients with this lesion is usually at a younger age (2 years) than in patients with idiopathic precocious puberty. Other CNS neoplasms that may cause true precocious puberty in either sex usually are located in or near the hypothalamus and include hypothalamic or optic gliomas, astrocytoma, ependymoma, dysgerminoma, and prolactinoma. Suprasellar dysgerminoma (ectopic pinealoma) in boys also may cause incomplete precocious puberty through tumor secretion of human chorionic gonadotropin (hCG).1,9,10



True precocious puberty may be observed in some children with long-standing untreated hypothyroidism. The increased production of gonadotropic hormones and prolactin seen in these patients may be due to a hormonal overlap in the pituitary response to thyroid deficiency. Affected patients show little, if any, development of secondary sexual characteristics, especially pubic hair. All of these changes regress with treatment of the hypothyroidism.1,7



Incomplete (Pseudosexual) Precocious Puberty in Girls






Etiology and Imaging: Gonadotropin levels are low, and the gonads remain immature. The most common ovarian source is an autonomous estrogen-secreting follicular (granulosa-thecal) cyst (Fig. 128-2). Other causes are estrogen-producing ovarian neoplasms, particularly granulosa cell (or granulosa-theca cell) tumors (Fig. 128-3) and rare estrogen-secreting adrenal neoplasms (adenomas or carcinomas).1,6,11




McCune-Albright syndrome consists of polyostotic fibrous dysplasia, cutaneous café au lait spots, and precocious puberty. The syndrome is found predominantly in females. Autonomously functioning ovarian cysts are seen in some cases. In others, no anatomic cause is noted. McCune-Albright syndrome occasionally presents as complete or true precocious puberty. It has been suggested that the initially partial or incomplete precocious puberty in these patients becomes complete (gonadotropin dependent) as the result of an early maturation of the hypothalamic-pituitary-gonadal complex, which is caused by a long-standing exposure to estrogen.1,6



Virilizing Disorders (Heterosexual Precocious Puberty)




Congenital Adrenal Hyperplasia




Overview and Imaging: Congenital adrenal hyperplasia is the most common form of hyperandrogenism. The increased production of androgenic substance is due in most cases to a deficiency of 21-hydroxylase and far less commonly to deficiencies in 11β-hydroxylase, 3β-hydroxysteroid dehydrogenase, or other enzymes involved in cortisol and/or aldosterone synthesis. Imaging of the adrenal gland will show enlargement (Fig. 128-4) that is usually bilateral and diffuse. The normal adrenal shape is maintained.1,12


Dec 20, 2015 | Posted by in PEDIATRIC IMAGING | Comments Off on Amenorrhea and Abnormalities of Puberty
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