Chloracne

Chloracne is an acne-like eruption of blackheads, cysts, and pustules associated with exposure to certain halogenated aromatic compounds, such as chlorinated dioxins and dibenzofurans. The lesions are most frequently found on the cheeks, behind the ears, in the armpits and groin region.
The condition was first described in German industrial workers in 1897 by Siegfried Bettmann, and was initially believed to be caused by exposure to chlorine (hence the name "chloracne"). It was only in the mid-1950s that chloracne was associated with aromatic hydrocarbons. The substances that may cause chloracne are now collectively known as chloracnegens.
Chloracne is particularly linked to toxic exposure to dioxins (byproducts of many chemical processes, including the manufacture of herbicides such as Agent Orange)—so much so that it is considered a clinical sign of dioxin exposure. The severity and onset of chloracne may follow a typical asymptotic dose-response relationship curve.
Cause.
Chloracne normally results from direct skin contact with chloracnegens, although ingestion and inhalation are also possible causative routes.
Chloracnegens are fat-soluble, meaning they persist in the body fat for a very long period following exposure. Chloracne is a chronic inflammatory condition that results from this persistence, in combination with the toxin's chemical properties. It is believed, at least from rodent models, that the toxin activates a series of receptors promoting macrophage proliferation, inducing neutrophilia and leading to a generalised inflammatory response in the skin. This process may also be augmented by induction of excess tumor necrosis factor in the blood serum.
The inflammatory processes lead to the formation of keratinous plugs in skin pores, forming yellowish cysts and dark pustules. The associated pus is usually a color of green approximating that of a tennis ball. The skin lesions occur mainly in the face, but in more severe cases they involve the shoulders and chest, the back, and the abdomen. In advanced cases, the lesions appear also on the arms, neck, thighs, legs, hands and feet.
In some instances, chloracne may not appear for three to four weeks after toxic exposure; however, in other cases—particularly in events of massive exposure—the symptoms may appear within days.
Treatment.
Once chloracne has been identified, the primary action is to remove the patient and all other individuals from the source of contamination. Further treatment is symptomatic.
Secondary infections on severe or persistent lesions may need to be treated with oral antibiotics or isotretinoin. However, chloracne itself can be highly resistant to any treatment.
The course of the disease is highly variable. In some cases the lesions may disappear within two years or so; however, in other cases the lesions may be effectively permanent (mean duration of lesions in one 1984 study was 26 years, with some workers remaining disfigured over three decades after exposure).
Related conditions.
Chloracne is very often seen in combination with hyperhidrosis (clammy, sweaty skin) and porphyria cutanea tarda (a skin condition of increased pigmentation, hair coarsening and blistering).