There are a wide range of skin pigmentations caused by drugs; indeed it is thought that 10–20% of all cases of acquired skin pigmentation are related to drugs (New Zealand Dermatological Society Incorporated, 2009). Although the pigmentation is usually benign, it can become socially unacceptable and may have a significant psychological impact on the patient. In most instances, stopping the drug will mean that the skin colour returns to normal; however, this may take some time and in some instances becomes permanent.
Pigmentation in the skin may occur for a number of reasons. These include:
- Accumulation of certain heavy metals in the dermis following dermal vessel damage.
- Sufficient accumulation of the heavy metal will cause pigment change without any associated increase in the level of melanin.
- Drug–pigment complexes might be formed with melanin in the skin, exposure to sunlight can trigger this reaction.
- Other drugs will trigger the accumulation of melanin as a non-specific post-inflammatory change. This may be worsened by exposure to sunlight.
- Some drugs can cause pigmentation by directly accumulating and/or reacting with substances in the skin.
Table 13.2 taken from www.dermnetnz.org outlines the clinical features associated with the drugs that are most likely to cause pigmentation.
Treatment involves stopping the drug involved if the pigmentation is causing distress. However, as can be seen from Table 13.2, most pigmentary changes are aggravated (and often triggered) by exposure to the sun. Therefore advice about sun protection is critical to reducing the problems associated with pigmentary changes.
| | | | | | Table 13.2 Drugs that can cause pigmentary changes. | | Drug/drug group | | Clinical features | | | Antipsychotics (chlorpromazine and related phenothiazines) | | - Bluish-grey pigmentation, especially in sun-exposed areas.
- Pigmentation is cumulative and some areas may develop a purplish tint.
- Pigmentation of the conjunctiva in the eye may also occur, along with cataracts and corneal opacities.
| | | Phenytoin | | - 10% of patients develop pigmentation of the face and neck resembling chloasma (clearly defined, roughly symmetrical dark brown patches).
- Fades after a few months when drug has been stopped.
| | | Antimalarials | | - About 25% of patients receiving chloroquine or hydroxychloroquine for several years develop bluish-grey pigmentation on face, neck and sometimes lower legs and forearms.
- Continuous long-term use may lead to blue-black patches, especially in sun-exposed areas.
- Nail beds and corneal and retinal changes may also develop.
| | | Cytotoxic drugs | | - Busulfan, cyclophosphamide, bleomycin and adriamycin have all produced hyperpigmentation to some degree.
- Banded or diffuse pigmentation of nails often occurs.
| | | Amiodarone | | - Blue-grey pigmentation in sun-exposed areas (face and hands).
- Photosensitivity occurs in 30–57% of patients whilst 1–10% show skin pigmentation.
- Skin pigmentation is reversible but may take up to 1 year for complete resolution after the drug has been stopped.
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Source: New Zealand Dermatological Society Incorporated (2009). | |
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