What the heck? Can't anything normal or expected happen to me? Does anyone else have this? Is it more common with other autoimmune diseases?
Emedicine said this:
Interestingly, the differential diagnosis includes:The pathophysiology of melasma is uncertain. In many cases, a direct relationship with female hormonal activity appears to be present because melasma occurs with pregnancy and with the use of oral contraceptive pills. Other factors implicated in the etiopathogenesis of melasma are photosensitizing medications, mild ovarian or thyroid dysfunction, and certain cosmetics.
The most important factor in the development of melasma is exposure to sunlight. Without the strict avoidance of sunlight, potentially successful treatments for melasma are doomed to fail...
Exactly which hormones and what mechanisms are involved in the development of melasma are yet to be determined. Genetic and hormonal influences in combination with ultraviolet radiation are the 2 most important causes of melasma, yet phototoxic and photoallergic medications and certain cosmetics have been reported to cause melasma in rare instances.
•Addison Disease
•Drug-Induced Photosensitivity
•Lupus Erythematosus, Discoid
•Mastocytosis
•Poikiloderma of Civatte
and
Pigmented Contact Dermatitis:
The hyperpigmentation in pigmented contact dermatitis is postulated to be caused by frequent and repeated contact with small amounts of sensitizing allergens primarily in cosmetic and textile materials. Nakayama hypothesized that allergens used in commercial products were too low in concentration to produce typical eczematous dermatitis, but rather accumulation of these allergens resulted allergic contact dermatitis, a type IV cytolytic reaction.[7, 8] This later reaction is characterized by vacuolar degeneration of the basal layer of the epidermis associated with pigment incontinence in the superficial dermis. The melanin pigment is slowly engulfed by macrophages; therefore, resolution of the hyperpigmentation is a prolonged process. Because most cases of pigmented contact dermatitis occur in patients with a darker completion, one hypothesis is that various pigment-genetic interactions contribute to the development of this condition.[4] Furthermore, Imokawa and Kawai have provided clinical evidence that various allergens implicated in allergic contact dermatitis can stimulate melanogenesis.[9]
So, I'm thinking I should suspect my various natural-ish shampoos, conditioners and hair spray. Crazy female hormones? (which wouldn't surprise me), thyroid dysfunction (also likely)?
Ugh, it never ends!!!!!!!!