Onset of the disorder is important information in the clinical history of the pigmentation disorder, because disease onset indicates whether the disorder is likely to be developmentally programmed (congenital) or acquired.
"Epidermal pigmentation disorders respond very well to lasers and intense pulsed light-based technologies. However, dermal pigmentation disorders are completely different," Dr. Zhou tells Dermatology Times. "They do not respond to such therapies. Topical preparations are used for depigmentation."
In diagnosing melanin pigmentation disorders, dermatologists should perform a comprehensive assessment to rule out malignancies and precursors to malignancies, as well as systemic diseases that require intervention. Onset of the disorder is important information in the clinical history of the pigmentation disorder, because disease onset indicates whether the disorder is likely to be developmentally programmed (congenital) or acquired.
Also, did the patient receive any previous treatments for the pigmentation disorder, and if so, what was the response to treatment?
In assessing the condition, physicians should consider the distribution of lesions, whether they are generalized or localized, and the appearance of the individual lesions, Dr. Zhou says.
"It is crucial to focus on the borders of individual lesions," he says. "Are the lesions clearly defined or poorly defined?"
Localized lesions that are poorly demarcated are likely to be dermal in origin.
"The most common pigmentation disorders that can be treated easily in a clinic are sun exposure and aging-related pigmentation disorders such as ephelides and solar lentigos," Dr. Zhou says. "Another common pigmentation disorder that is easily treated is melasma."
Patients also seek treatment for flat seborrheic keratoses (SK) or deep-penetrating nevi (DPN) in the early stages, for mucosal melanosis, and for café-au-lait macules (CALM).
"Epidermal pigmentation disorders generally respond to destructive therapies, especially QS laser therapies," Dr. Zhou notes. "Intense-pulsed laser is less effective, but there is less downtime."
The most common localized pigmentation disorders affecting the epidermis are ephelides, or freckles. Ephelides appear as macular brown pigmentation in sun-exposed areas, usually on the face. They are more common in light-skinned individuals, and the tendency to have freckles is a heritable condition. The degree of pigmentation changes according to UV exposure, with freckles usually darkening in the summer and lightening in the winter.
QS lasers and intense-pulsed laser treatments are effective for depigmentation, and ephelides occasionally respond to topical depigmentation preparations. Whether treatment is considered is a culturally based decision.
"In general, east Asians are more likely to seek treatment for this condition," Dr. Zhou says.
Other common epidermal lesions, larger and darker than ephelides, are solar lentigos, also known as actinic or senile lentigo. These lesions range in size and shape from macules to thin papules or plaques. Solar lentigos are induced by chronic sun exposure.
"Patients usually develop solar lentigos starting in the 20s, and the lesions increase with advancing age," Dr. Zhou says. "They are more common in East Asians than Caucasians."
"In my practice the most effective treatment for solar lentigo is Q-switched laser therapy," Dr. Zhou remarks. "Cryotherapy in dark-skinned individuals may cause permanent hypopigmentation and should be avoided."
Mucosal melanosis arises from increased melanin in the mucosal squamous cells. There is no significant increase in the number of melanocytes.