In all its forms, congenital adrenal hyperplasia due to 21-hydroxylase deficiency accounts for about 95% of diagnosed cases of CAH. Unless another specific enzyme is mentioned, "CAH" in nearly all contexts refers to 21-hydroxylase deficiency. (The terms "salt-wasting CAH", and "simple virilizing CAH" usually refer to subtypes of this condition.) CAH due to deficiencies of enzymes other than 21-hydroxylase present many of the same management challenges, as 21-hydroxylase deficiency, but some involve mineralocorticoid excess or sex steroid deficiency. Screening
Currently, in the United States and over 40 other countries, every child born is screened for 21-hydroxylase CAH at birth. This test  detects elevated levels of 17α-hydroxyprogesterone (17-OHP). Detecting high levels of 17-OHP enables early detection of CAH. Newborns detected early enough can be placed on medication and live  relatively normal lives.The screening process, however, is characterized by a high false-positive rate. In one study, CAH screening had the lowest positive predictive value (111 true-positive cases among 20,647 abnormal screening results in a 2-year period, or 0.53%, compared with 6.36% for biotinidase deficiency, 1.84% for congenital hypo-thyroidism, 0.56% for classic galactosemia, and 2.9% for phenylketonuria). According to this estimate, 200 unaffected newborns required clinical and laboratory follow-up for every true case of CAH.In 2020, Wael AbdAlmageed from USC Information Sciences Institute and Mimi Kim from USC Keck School Of Medicine led a joint study in which they used deep learning technology to analyze the facial morphology and features of CAH patients compared to control.
This categorization is important because large congenital melanocytic nevi are associated with an increased risk of melanoma, a serious type of skin cancer.Small: <1.5 cm
Medium: 1.5–19.9 cm
Large: ≥ 20 cm
Nevus of Ito
Nevus of Ota

Decreased melanin
Acquired
Nevus anemicus

Congenital
Nevus depigmentosus
		
Additional types of nevi do not involve disorders of pigmentation or melanocytes. These additional nevi represent hamartomatous proliferations of the epithelium, connective tissue, and vascular malformations. Epidermal nevi
These nevi represent excess growth of specific cells types found in the skin, including those that make up oil and sweat glands. Verrucous epidermal nevus
Nevus sebaceous
Nevus comedonicus
Eccrine nevus
Apocrine nevus

Connective tissue nevi
Connective tissue nevi represent abnormalities of collagen in the dermis, the deep layer of the skin. Collagenoma
Elastoma

Vascular nevi
These nevi represent excess growth of blood vessels, including capillaries. Nevus simplex (nevus flammeus nuchae), also known as a stork bite or salmon patch. Intramucosal nevi
An intramucosal nevus is a nevus within the mucosa as found in for example the mouth and genital areas. In the mouth, they are found most frequently on the hard palate. They are typically light brown and dome-shaped. Intramucosal nevi account for 64% of all reported case of oral nevi. Diagnosis
Nevi are typically diagnosed clinically with the naked eye or using dermatoscopy. More advanced imaging tests are available for distinguishing melanocytic nevi from melanoma, including computerized dermoscopy and image analysis. The management of nevi depends on the type of nevus and the degree of diagnostic uncertainty. Some nevi are known to be benign, and may simply be monitored over time.