Acquired hypertrichosis is most commonly iatrogenic. Offending agents include streptomycin, especially in children, diazoxide, penicillamine, psoralens and minoxidil. The condition usually resolves following withdrawal of the drug.
Other causes include:
- as a manifestation of systemic disease, for example:
- hepatoerythropoietic porphyria
- endocrine dysfunction - in children with hypothyroidism, a profuse growth of hair may occasionally be seen on the back and extensor surfaces of the limbs. Localised hypertrichosis may be seen over the plaques of myxoedema in some patients with hyperthyroidism. In anorexia nervosa, hypothalamic effects are thought to be responsible for the hypertrichosis occasionally seen on the face, trunk and arms
- gross malnutrition - for example, a generalised hypertrichosis was seen in children during the potato famine in the 19th century
- following mercury poisoning - acrodynia or pink disease
- during the second month of pregnancy - often, affecting the eyebrows
- acquired Immunodeficiency syndrome
- brain injury
- polymyositis
- primary biliary cirrhosis
- shock
- SLE (1)
- as a result of repeated irritation, friction or chronic inflammation, for example:
- following occlusion of a limb by a plaster of Paris cast
- after prolonged application of mercurial ointment and iodine
- occupational - for example, on the shoulders of sack bearers
- following excision of warts on the dorsum of the hands and fingers
- overlying chronic osteomyelitis of the tibia
Acquired localized hypertrichosis has also been reported to occur in response to local trauma, cutaneous hyperaemia and peripheral neuropathy (2)
Rarely, acquired hypertrichosis lanuginosa can occur as a cutaneous paraneoplastic syndrome, most commonly associated with adenocarcinoma of the lung and colon, but also with many other malignancies (1,3)
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