The differential diagnosis of melasma should be made with post-inflammatory pigmentation, pigmented cosmetic dermatitis, hyperthyroidism, actinic lichen planus, HIV-associated pigmentation, drug-induced facial pigmentation, and poikiloderma of Civatte
. The histories (for post-inflammatory pigmentation, cosmetic dermatitis, and drug-induced pigmentation), clinical findings (for cosmetic dermatitis, actinic lichen planus, drug-induced pigmentation, and poikiloderma of Civatte
), laboratory tests (for thyroid function tests, HIV serology, hyperthyroidism, and HIV-associated pigmentation), patch tests (for cosmetic dermatitis), and histopathology are useful for diagnosis (2).
A This sounds like it may be a condition called "poikiloderma of Civatte
," a term used to describe a change in the color and/or texture of the skin due to sun-related aging.
Physic hyperpigmentations: due to cumulative effect, solar radiation exposure causes senile lentigo, actinic keratosis or photosensitivity caused by perfumes and cosmetic compounds (Riehl's melanosis, poikiloderma of Civatte
) or furocoumarins from certain plants (phytophotodermatitis).
Hyperpigmentation, as in Berloque dermatitis, Riehl's melanosis, poikiloderma of Civatte
, and erythrosis pigmentata faciei of Brocq, has been attributed to bergamot oil in eau-de-Cologne or from tars in cosmetics.
(22) Differential Diagnoses (29): Acquired bilateral nevus of Ota-like macules, Argyria, Addison's disease, Atopic dermatitis, Berloque dermatitis, Chronic actinic dermatitis, Chrysiasis, Contact dermatitis, Cutaneous lupus erythematosus, Drug-induced hyperpigmentation, Erythema dyschromicumperstans, Erythromelanosisfollicularisfaciei et colli, Exogenous ochronosis, Facial erythema abigne, Lentigo, Lichen planus, actinic type, Mastocytosis, Minocycline pigmentation, Photosensitivity reactions, Polymorphous light eruption, Poikiloderma of Civatte
, Postinflammatory hyperpigmentation, Riehl'smelanosis, Skin infections
Further, poikiloderma of Civatte
 is a different condition again.
Berson, the problem sounds like Poikiloderma of Civatte
, a condition that usually affects the skin on the sides of the neck and is related to accumulated sun exposure over the years.