
Acne, also known as acne vulgaris, is a long-term skin disease that occurs when dead skin cells and oil from the skin clog hair follicles. Typical features of the condition include blackheads or whiteheads, pimples, oily skin, and possible scarring. It primarily affects skin with a relatively high number of oil glands, including the face, upper part of the chest, and back. The resulting appearance can lead to anxiety, reduced self-esteem, and, in extreme cases, depression or thoughts of suicide.

Adolescence is a transitional stage of physical and psychological development that generally occurs during the period from puberty to legal adulthood. Adolescence is usually associated with the teenage years, but its physical, psychological or cultural expressions may begin earlier and end later. For example, puberty now typically begins during preadolescence, particularly in females. Physical growth and cognitive development can extend into the early twenties. Thus, age provides only a rough marker of adolescence, and scholars have found it difficult to agree upon a precise definition of adolescence.

In Islamic legal terminology, bāligh or mukallaf of muhallaq or murahiq or muhtalim refers to someone who has reached maturity or puberty, and has full responsibility under Islamic law.

A comedo is a clogged hair follicle (pore) in the skin. Keratin combines with oil to block the follicle. A comedo can be open (blackhead) or closed by skin (whitehead) and occur with or without acne. The word comedo comes from the Latin comedere, meaning 'to eat up', and was historically used to describe parasitic worms; in modern medical terminology, it is used to suggest the worm-like appearance of the expressed material.

Estrogen, or oestrogen, is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane, is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy.

Pubic hair is terminal body hair that is found in the genital area of adolescent and adult humans. The hair is located on and around the sex organs and sometimes at the top of the inside of the thighs. In the pubic region around the pubis bone, it is known as a pubic patch. Pubic hair is found on the scrotum in the male and on the vulva in the female.

Teenage pregnancy, also known as adolescent pregnancy, is pregnancy in a female under the age of 20. Pregnancy can occur with sexual intercourse after the start of ovulation, which can be before the first menstrual period (menarche) but usually occurs after the onset of periods. In well-nourished girls, the first period usually takes place around the age of 12 or 13.

Tuber cinereum hamartoma is a benign tumor in which a disorganized collection of neurons and glia accumulate at the tuber cinereum of the hypothalamus on the floor of the third ventricle. It is a congenital malformation, included on the spectrum of gray matter heterotopias. Formation occurs during embryogenesis, typically between days 33 and 41 of gestation. Size of the tumor varies from one to three centimeters in diameter, with the mean being closer to the low end of this range. It is estimated to occur at a frequency of one in one million individuals.