Skin Hyperpigmentation: A Brief Summary
* by Lama Alkahtani
Hyperpigmentation occurs when there is darkening of an area of skin in the body; it is caused by an increase in dermal and epidermal melanin production and retention.
Hyperpigmentation takes on different forms and could affect an area of the face, arm, neck or back in a diffuse or localized manner. Hyperpigmentation is present in a number of different diseases and conditions. These include some of the following:
- Patchy Pigmentation also known as chloasma.
- Could be due to an increase in hormonal exposure as in the case of pregnancy, OCP use, hormonal therapy or an endocrine disease. Increased sun exposure and phototoxic drugs seem to play an important part in Melasma.
- Key diagnostic features include a characteristic brown to grey hyperpigmentation, typically affects the centrofacial, malar and mandibular areas.
- Investigations include skin biopsies and wood lamp examination.
- Skin biopsies from patients with melasma show an increase in the number of melanocytes and melanin-laden macrophages (melanophages). In addition, later-stage melanocytes may show greater numbers of melanocytes containing melanosomes. Solar elastosis is increased by 83% in patients with melasma, linking back to the important role of cumulative sun exposure in this disease.
- Management depends on the state of the patient. If the patient is pregnant, first-line therapy includes azelaic acid and sun protection. For non-pregnant patients, management includes azelaic acid, chemical peels, laser therapy cryotherapy, dermabrasion plus sun protection.
- Adrenal insufficiency causes an increase in the production of ACTH hormone due to the negative feedback on the pituitary gland resulting in an increase in the production of melanin as a result of an increase in the levels of melanocyte stimulating hormone (MSH).
- Hyperpigmentation is usually seen in high-pressure areas in the body like the elbows and knees. Mucocutaneous hyperpigmentation is noted particularly in the buccal mucosa. Some extent of hyperpigmentation does occur in the hands on the palmar creases and nail beds. In contrast, other skin findings may include vitiligo! (due to the autoimmune association).
Cutaneous drug reaction.
- Certain drugs like tetracycline, amiodarone along with other drugs can cause hyperpigmentation.
- Tetracycline an antibiotic can cause blue-grey discoloration of exposed skin, teeth discoloration and discoloration of previous scars.
- Amiodarone can cause blue-grey discoloration of exposed skin, it can also cause yellow discoloration of the eyes.
- Occurs when there is damage to the epidermal skin layer, which brings about the deposition of melanin within keratinocytes.
- Localized in the area of disease, so where the injury first occurred.
- It could be as a result of acne, previous scars, skin burns and any other dermatitis.
- Diagnosis is made through a careful history and examination, with dermal melanocytes giving off a grey-purple skin color. Skin biopsy may show patchy epidermal or dermal melanosis.
King Saud University
Riyadh, Saudi Arabia