Alopecia (overview) - Altmeyers Encyclopedia

Synonym(s)

Alopecia; Bald; Balding; Glabrification; Hairlessness

Definition
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Condition of visible hairlessness on parts of the body normally covered with terminal hair, especially the capillitium. The process of hair loss itself is called effluvium.
Alopecia can be localised (focal), diffuse or total.
A distinction is made between:
- scarring (irreversible) alopecia, which is accompanied by destruction of the hair follicle
- non-scarring alopecia (increased entry of follicles into the telogen stage or involution from terminal hair to vellus hair).

Classification
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For an overview of the various causes of alopecia, see table

Tables
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Important causes of alopecia

	Etiology/Cause	Clinical picture
Scarring alopecia	Congenital defects and genetic disorders	Aplasia cutis congenita, X-linked recessive ichthyosis, epidermal nevus, hemiatrophia progressiva faciei (Romberg), incontinentia pigmenti type Bloch-Sulzberger, porokeratosis mibelli, dyskeratosis follicularis, scarring types of the epidermolysis bullosa group, cutaneo-ossal syndrome, keratosis pilaris syndrome
	Infections by fungi, bacteria, protozoa, viruses	Tinea capitis, microspores, syphilis acquisita (Alopecia specifica), leprosy (Alopecia lepromatosa), folliculitis sclerotisans nuchae, cutaneous leishmaniasis, zoster
	Tumors	Basal cell carcinoma, spinocellular carcinoma, skin metastases (alopecia neoplastica), adnexal tumors, lymphoma of the skin; lipomas; alopecia lipoedematosa (rare)
	Physical or chemical noxae	Scarring after mechanical trauma, burns, chronic radiodermatitis, burns (alkalis and acids)
	Dermatoses	Acne conglobata, lupus erythematosus (CDLE), lichen planus, lichen planopilaris, postmenopausal fibrosing frontal alopecia, circumscribed scleroderma, sarcoidosis, perifolliculitis capitis abscedens et suffodiens, psoriasis capitis, pseudopelade (Brocq), dermatomyositis, necrobiosis lipoidica (rarely on the capillitium), Lichen sclerosus et atrophicus (rarely on the capillitium), scarring pemphigoid (rarely on the capillitium), Lassueur-Graham-Little syndrome, mucinosis follicularis, folliculitis decalvans, erosive pustular dermatitis of the capillitium (rarely), amyloidosis (rarely), alopecia lipoedematosa (rarely)

Non-cicatrizing alopecia	Alopecia androgenetica (male and female pattern)
	Alopecia areata (circumscribed, more rarely diffuse)
	Metabolic disorders of different genesis	Malnutrition, endocrine disorders (e.g. thyroid dysfunction, disorders of the NNR)
	Drug and chemical effects	Cytostatic and immunosuppressive drugs (e.g. cyclophosphamide, methotrexate, colchicine, azathioprine), anticoagulants (heparin, coumarins), thiouracil, carbamazole, vitamin A, levodopa, propranolol, butyrophenones, bromocriptine, bismuth preparations, thallium, mercury
	Hereditary syndromes	Alopecia congenita, hypotrichosis congenita hereditaria generalisata (Marie-Unna), anhidrotic ectodermal dysplasia, Moynahan syndrome
	Traumas	Trichotillomania, Alopecia marginalis
	Systemic diseases	Infectious diseases, collagenoses, lymphomas, tumours of different genesis