Melanodermatitis toxica L81.4

Exogenously triggered, chronic phototoxic, partly also photoallergic reaction with post-inflammatory pigment incontinence.

Probably identical with the clinical picture described by Riehl(Riehl melanosis). S.a.u. Melanosis perioralis et peribuccalis.

Caused by contact with lubricating oil and its derivatives, tar vapour, uncleaned Vaseline (see alsoVaselinoderm), phototoxic and photosensitizing substances.

Melanodermatitis toxica as well as melanosis and Riehl melanosis are an expression of a mostly subclinical, chronically persistent, photosensitive reaction. The discrete superficial dermatitis leads to melanocytic hypertrophy and hyperplasia. These processes are followed by increased epidermal pigmentation and a vivid pigment incontinence. The dermal pigmentation essentially determines the dark shade (brown to slate gray) of the lesion.

The disease either begins with an acute, itchy dermatitis, which can also be vesicular in cases of high sensitivity. In most cases, the disease presents as subacute or chronic dermatitis. Over time, dirty-brown hyperpigmentation with follicular keratoses, delicate atrophy and telangiectasia appear. Recurrent activity is observed after UV exposure.

The discolorations are dirty grey, brown-red to blackish. They are usually not diffuse but rather reticular. Hyperkeratosis, which is difficult to remove, forms over longer periods. Comedones can also be found.

Strict avoidance of the causative substances (mostly fragrances, perfumes, cosmetics, medicines). Slow regression is possible if the cause is avoided.

As a rule, over-painting of disturbing hyper pigmentations (e.g. Dermacolor) and light protection agents (e.g. Contralum ultra, Anthelios) are the most sensible solutions. Depigmenting external agents like hydroquinone cream(e.g. Pigmanorm) and the more effective combination of hydroquinone-hydrocortisone-Vit. A-acid (e.g. Pigmanorm) are not very useful as it is not only an epidermal pigment but also a dermal pigment which has "dripped off" there in the course of the chronic inflammatory reaction.

1. Hoffmann E, Habermann R (1918) Medicinal and industrial dermatoses caused by war substitutes (Vaseline lubricating oil) and peculiar melanodermatitis. Dtsch Med Wochenschr 4: 261-264
2. Kang HY (2012) Melasma and aspects of pigmentary disorders in Asia. Ann Dermatol Venereol 139 Suppl 3: 92-55
3. Khanna N et al (2011) Facial melanoses: Indian perspective. Indian J Dermatol Venereol Leprol 77:552-563