Chloracne and its potential clinical implications

Effects and mechanisms of polycyclic aromatic hydrocarbons in inflammatory skin diseases

Polycyclic aromatic hydrocarbons (PAHs) are hydrocarbons characterized by the presence of multiple benzene rings. They are ubiquitously found in the natural environment, especially in environmental pollutants, including atmospheric particulate matter, cigarette smoke, barbecue smoke, among others. PAHs can influence human health through several mechanisms, including the aryl hydrocarbon receptor (AhR) pathway, oxidative stress pathway, and epigenetic pathway. In recent years, the impact of PAHs on inflammatory skin diseases has garnered significant attention, yet many of their underlying mechanisms remain poorly understood. We conducted a comprehensive review of articles focusing on the link between PAHs and several inflammatory skin diseases, including psoriasis, atopic dermatitis, lupus erythematosus, and acne. This review summarizes the effects and mechanisms of PAHs in these diseases and discusses the prospects and potential therapeutic implications of PAHs for inflammatory skin diseases.

Current skin symptoms of Yusho patients exposed to high levels of 2,3,4,7,8-pentachlorinated dibenzofuran and polychlorinated biphenyls in 1968

Yusho was a mass food poisoning event due to the ingestion of rice oil contaminated with polychlorinated biphenyls (PCBs) and various dioxins and dioxin-like compounds. At its outbreak in 1968, Yusho patients suffered severe skin symptoms. Although the blood concentrations of PCBs and dioxins, especially highly toxic 2,3,4,7,8-pentachlorinated dibenzofuran (2,3,4,7,8-PeCDF) remain high in these patients, extensive analysis has not been performed on their current skin symptoms. We categorized and evaluated the specific skin symptoms in Yusho in 2012 by grading their severity using an arbitrary scoring system, and analyzed their correlations with the blood concentrations of 2,3,4,7,8-PeCDF and PCBs. A total of 352 Yusho patients underwent annual dermatological check-ups, in which five skin symptoms: black comedones, acneiform eruptions, scar formation, pigmentation and nail deformity, were evaluated for their distribution and severity. Approximately one-third of Yusho patients still presented with black comedones, acneiform eruptions and scar formation; the distributions of these symptoms were similar to those at the time of the Yusho outbreak. The mean blood concentrations of 2,3,4,7,8-PeCDF and total PCBs in Yusho patients were still higher than those in controls. The prevalence and severity of black comedones were correlated with age. Severity scores of black comedones and scar formation were positively correlated with 2,3,4,7,8-PeCDF blood level, and those of black comedones, scar formation, and pigmentation were positively correlated with total PCBs blood level. This study suggests that 2,3,4,7,8-PeCDF and PCBs remaining in Yusho patients still play crucial roles in the development of skin symptoms in Yusho.

Dioxin-induced chloracne--reconstructing the cellular and molecular mechanisms of a classic environmental disease

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is among the most toxic pollutants known to date that serves as a prototype for a group of halogenated hydrocarbon compounds characterized by extraordinary environmental persistence and unique ability to concentrate in animal and human tissues. TCDD can elicit a complex array of pleiotropic adverse effects in humans, although chloracne, a specific type of acne-like skin disease, is the only consistent manifestation of dioxin intoxication, thus representing a 'hallmark' of TCDD exposure. Chloracne is considered to be one of the most specific and sensitive biomarkers of TCDD intoxication that allows clinical and epidemiological evaluation of exposure level at threshold doses. The specific cellular and molecular mechanisms involved in pathogenesis of chloracne are still unknown. In this review, we summarize the available clinical data on chloracne and recent progress in understanding the role of the dioxin-dependent pathway in the control of gene transcription and discuss molecular and cellular events potentially involved in chloracne pathogenesis. We propose that the dioxin-induced activation of skin stem cells and a shift in differentiation commitment of their progeny may represent a major mechanism of chloracne development.

Klinische Formen der Akne

Acne is a very common dermatosis with characteristic clinical features. It is a polymorphic disease. The clinical expression ranges from non-inflammatory closed and open comedones to inflammatory papules, pustules, and nodules. Most patients have a mixture of non-inflammatory and inflammatory lesions, although some have predominantly one or the other. Acne varies in severity from a very distressing, socially disabling disorder to a state that has been regarded as physiological by some authors. The most severe forms of acne are acne fulminans and acne inversa. Although acne may occur in all age groups, it is most prevalent during adolescence. It is not known why acne subsides in most patients but persists into adulthood in some. Certain medications may be associated with provocation, perpetuation, or exacerbation of pre-existing acne or with acneiform eruptions. Acne-like disorders include rosacea, pseudofolliculitis barbae, and other conditions that share clinical features with acne.

Comedone formation: Etiology, clinical presentation, and treatment

An important feature in the etiology of acne is the presence of pilosebaceous ductal hypercornification, which can be seen histologically as microcomedones (Fig 1) and clinically as blackheads, whiteheads, and other forms of comedones, such as macrocomedones. There is a significant correlation between the severity of acne and the number and size of microcomedones (follicular casts), the presence of which is a measure of comedogenesis. This correlation can be demonstrated by skin surface biopsy using cyanoacrylate gel. In this procedure, microcomedones are sampled by applying cyanoacrylate gel to the skin surface. A glass microscopic slide is then applied on top of the gel and pressed firmly onto the skin for 1 minute(1-3). The glass slide is gently removed, taking with it the upper part of the stratum corneum and microcomedones, which are then analyzed by low-power microscopy or digital image analysis.(1-3)

Photocontact dermatitis and chloracne: two major occupational and environmental skin diseases induced by different actions of halogenated chemicals

Among occupational and environmental disorders, contact or photocontact dermatitis and an acneiform eruption are two major skin disorders. Photocontact dermatitis was historically caused by various halogenated salicylanilides, while the acne is induced by halogenated aromatic hydrocarbons and thus called chloracne. Therefore, it should be noted that halogenated chemical compounds are important causative agents in the occupational and environmental medicine. In photocontact dermatitis, photoconjugation of epidermal cells with a photohaptenic halogenated chemical is the initial step. Langerhans cells serve as antigen-presenting cells and T cells sensitized by photoantigen-bearing Langerhans cells induce this photosensitivity. On the other hand, in chloracne, halogeneted hydrocarbons render keratinocytes of the outer root sheath and sebaceous duct hyperplastic. The dilated infundibulum of most hair follicles is then filled with comedone that consist of many accumulated layers of keratinized cells and sebum. Therefore, halogenated chemicals exhibit different actions, i.e. the induction of an immunologic consequence and the modulation of keratinocyte biology. These two conditions also provide good experimental models for investigating dermatology.

Chloracne: histopathologic findings in one case

BACKGROUND

Chloracne is an acneiform eruption due to poisoning by halogenated aromatic compounds having a specific molecular shape. This condition is always a symptom of systemic poisoning by chemical chloracnegens and not just a cutaneous disorder.

METHODS

We have studied a patient with severe chloracne who showed cutaneous lesions involving mostly the face and the axillae.

RESULTS

Histopathologic study of the facial lesions demonstrated that almost every vellus hair follicle was involved, showing a dilated infundibulum filled by a keratotic plug. This keratotic material was mostly composed of orthokeratotic basket-weave basophilic corneocytes, namely infundibular keratin, although there were also some dilated infundibula containing eosinophilic laminated or granular sebum at their center. Small infundibular cysts were more numerous than comedones. Mature and well-developed sebaceous glands were seen at the base of many of the dilated infundibula and no squamous metaplasia of the sebaceous glands or ducts could be demonstrated. Hyperpigmentation of the lesions resulted from hyperproduction of melanin by a normal number of melanocytes along the basal layer of the epidermis and infundibular epithelium. Abundant melanin granules also impregnated the corneocytes of the infundibular plugs.

CONCLUSIONS

Our findings support the notion that tiny infundibular cysts rather than comedones represent the basic lesions of chloracne.

Punctate keratoderma-like lesions on the palms and soles in a patient with chloracne: a new clinical manifestation of dioxin intoxication?

We report what we believe to be a novel skin manifestation of dioxin intoxication. A 30-year-old woman with 2,3,7, 8-tetrachlorodibenzo-p-dioxin levels of 144,000 pg g-1 blood fat presented with severe chloracne that affected the entire integument. She also exhibited acral granuloma annulare-like lesions and distal onycholysis and, at a later time point, showed signs of hypertrichosis, as well as brownish-grey hyperpigmentation of the face. In addition, she developed punctate keratoderma-like lesions on the palms and soles. These lesions were negative for human papillomavirus and histologically characterized by cone-shaped hyperkeratoses invaginating, but not penetrating, into the dermis. Squamous syringometaplasia of the eccrine glands was observed in the immediate vicinity of these lesions. Both clinically and histologically these alterations are essentially indistinguishable from what is described as keratosis punctata palmaris et plantaris (KPPP). Although a fortuitous coincidence of chloracne and KPPP cannot be formally excluded, the possibility exists that in our patient toxic levels of dioxin were causally involved in this disorder of keratinization.

Comedogenesis: some new aetiological, clinical and therapeutic strategies

Hypercornification is an early feature of acne and precedes inflammation. It is associated with ductal hyperproliferation and there are many controlling factors such as androgens, retinoids and cytokines. Cycling of normal follicles and of comedones may explain the natural resolution of comedones and, in the longer term, resolution of the disease itself. There is a need to tailor treatment according to comedonal type. Suboptimal therapy can often result from inappropriate assessments of comedones, especially microcomedones, missed comedones, sandpaper comedones, submarine comedones and macrocomedones. Macrocomedones can produce devastating acne flares, particularly if patients are inappropriately prescribed oral isotretinoin. Gentle cautery under topical local anaesthesia is a useful therapy in the treatment of such lesions. The newer retinoids and new formulations of all-trans-retinoic acid show a better benefit/risk ratio. Evidence-based studies are required to allow adequate comparisons.

Olestra increases faecal excretion of 2,3,7,8-tetrachlorodibenzo-p-dioxin

Two patients with chloracne had concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) of 144,000 and 26,000 pg/g blood lipids. Olestra, a non-digestible, lipophilic dietary fat substitute accelerated the patients' intestinal excretion of TCDD by eight to ten fold. This is sufficient to reduce the normally observed elimination half life of TCDD from about 7 years to 1-2 years.

Serum dioxin, chloracne, and acne in veterans of Operation Ranch Hand

The possible relationship between exposure to Agent Orange and its contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin), during the Vietnam War and chloracne was investigated. The index subjects were veterans of Operation Ranch Hand, the unit responsible for aerial herbicide spraying in Vietnam from 1962 to 1971. Other Air Force veterans who served in Southeast Asia during the same period, but who were not involved with spraying herbicides, served as comparisons. None of the Ranch Hand veterans were diagnosed with chloracne; therefore, we restricted our analyses to acne. We found no meaningful or consistent association between dioxin exposure and prevalence of acne without or with regard to anatomical location. These results suggested that exposure of Ranch Hand veterans to dioxin was insufficient for the production of chloracne or perhaps the exposure may have caused chloracne that resolved and was currently undetectable.

Chloracne in the 1990s

BACKGROUND

Chloracne is a disease associated with toxicity of halogenated compounds used in some industrial processes. A patient affected by chloracne led us to study a total of nine cases from a single factory.

METHODS

We studied the clinical features of nine patients exposed chronically to chlorobenzenes. On all of them blood samples were drawn and biopsies of affected skin and liver were taken. Their work environment was visited and studied.

RESULTS

All nine patients were men and had polymorphic skin lesions, characterized mainly by comedones and cysts. They had chronic conjunctivitis and seven had cysts in the Meibomian glands. All of them had polyneuropathy and liver damage and seven had hypertriglyceridemia. Compounds known to cause chloracne were found in exceedingly high concentrations in the water used in the workplace.

CONCLUSIONS

Every patient exposed to halogenated compounds with the cutaneous manifestations of chloracne should be carefully investigated for systemic complications (such as ophthalmic, neuropathic, hepatic, and lipoprotein abnormalities).

Interactive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and retinoids on proliferation and differentiation in cultured human keratinocytes: quantification of cross-linked envelope formation

Dioxins are potent inducers of chloracne in humans. This skin aberration can be interpreted as an altered differentiation pattern of acinar sebaceous base cells and a change in the rate of terminal differentiation of the keratinocytes. We measured this rate induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in primary cultures of human keratinocytes. As parameters for differentiation, we quantified the 35S-methionine incorporation into cross-linked envelopes (revealing the total CLE biomass), as well as the number of microscopically visible CLEs. It was shown that TCDD is a very potent inducer of both CLE biomass and number with a half-maximal effect concentration (EC50) of 1.4 nM. CLE biomass was maximally increased 10-fold and the number of cells in culture producing a CLE was increased from 15% in control cultures to maximally 75% of the cells in TCDD-treated cultures. Both effects were Ca(2+)-dependent and increased with elevated cell density, being optimal in post-confluent cultures. Retinoic acid dose-dependently decreased the effect of 10(-8) M TCDD, 10(-6) M having a nearly complete antagonistic action. This interaction of retinoic acid with TCDD-induced differentiation was non-competitive. Retinol was equally potent as an antagonist of the TCDD-induced elevation of CLE formation as compared with retinoic acid. Retinyl palmitate and etretinate were not very effective as TCDD antagonists. Supplementation of hydrocortisone suppressed the TCDD-induced keratinocyte differentiation. It was concluded that CLE biomass quantification provides a reliable and sensitive parameter for keratinocyte differentiation. In this in vitro system it is shown that TCDD strongly induces a switch from proliferation to terminal differentiation and that this effect can be antagonized effectively by retinoic acid and retinol.

Severe halogen acne due to a trifluoromethylpyrazole derivative and its resistance to isotretinoin

We report a case of severe chloracne, with systemic involvement, following occupational exposure to dihydrotrifluoromethylphenyl benzothiopyranopyrazolone, which, to our knowledge, has not been previously reported as a cause of chloracne. Aggressive drug treatment, including high-dose oral isotretinoin was of limited benefit in suppressing the disease activity.

Light cautery and EMLA in the treatment of chloracne lesions

We report six patients with chloracne, unresponsive to conventional therapy, whose lesions were cleared by treatment with EMLA (eutectic mixture of lignocaine [lidocaine] 25 mg/g and prilocaine 25 mg/g) topical anaesthesia and light cautery. To the best of our knowledge, this form of treatment for chloracne has not previously been reported.

Dowling-Degos' disease mimicking chloracne

We describe a patient with clinical features that resembled severe chloracne; however, histopathologic findings revealed a reticulated pigmented anomaly. Innumerable comedones, many cysts, acneiform scarring, and flexural and facial pigmentation were noted in this patient, who is a machinist. A serum test for polychlorinated biphenyl was negative, which eliminated a diagnosis of chloracne. The spectrum of clinical features of the histologically well-defined Dowling-Degos' disease is discussed; in this disease lesions can be flexural or acral and can appear as macules, comedones, or cysts.

Induction of terminal differentiation in cultured human keratinocytes by polychlorinated aromatic hydrocarbons as measured by cell size analysis

Polychlorinated aromatic hydrocarbons modulate the proliferation and differentiation of human epidermal cells in vivo and in culture. One of the earliest events in the process of terminal differentiation is the increase in cell size. In this report the usefulness of morphometric cell size analysis as a quantifiable marker for chemical-induced differentiation was examined. Concentration-related increases in cell size distribution were induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 2,3,4,7,8-pentachlorodibenzofuran in normal human keratinocytes and cells from an SV40-transformed keratinocyte cell line (SVK14) whereas the analog 1,2,3,4-tetrachlorodibenzo-p-dioxin did not affect the cell size distribution up to a concentration of 100 nM. The minimal effective concentrations of five 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins/dibenzofurans and a coplanar polychlorbiphenyl necessary to induce an increase in cell size distribution were determined in SVK14 cells. It was found that the potency of these compounds relative to that of 2,3,7,8-TCDD correlated well with the toxicity equivalency factors observed in other test systems. This indicates that the keratinocyte cell assay is a useful method for establishing the relative potency of various "dioxins" and their mixtures.

Cutaneous manifestations of tetrachlorodibenzo-p-dioxin in children and adolescents. Follow-up 10 years after the Seveso, Italy, accident

After an accident in a chemical plant in Seveso, Italy, on July 10, 1976, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) spread over a populated area. The event was exceptional because children were also affected and because the contamination took place not only through direct exposure but also through inhalation and the ingestion of contaminated foods, especially fruits and vegetables. This paper illustrates the early dermatologic lesions, the late acneic (chloracne) lesions, and their evolution during a 10-year period. Peculiar cutaneous findings, histologic data, and a comparison with previously reported similar accidents are also included.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) modulates epidermal growth factor (EGF) binding to basal cells from a human keratinocyte cell line

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) modulates the proliferation, differentiation, or both, of epidermal keratinocytes in vivo and in culture. The growth of epidermal cells in culture is regulated by several biochemical mediators including epidermal growth factor (EGF). In this report the actions of TCDD on EGF binding in a basal cell population from a human keratinocyte cell line were examined. TCDD decreased the specific binding of 125I-EGF to basal cells by 40% within 96 hr. This reduction in EGF binding could not be attributed to changes in the state of differentiation as assessed by cell size and morphology, and cornified envelope competence, a marker of terminal differentiation. Modulation of EGF binding by TCDD was concentration-dependent (EC50 = 1 nM) and stereospecific, suggesting involvement of the Ah receptor. Scatchard analysis of EGF binding to the basal cells indicated a single class of high-affinity sites in both control (Kd = 0.14 nM) and treated (Kd = 0.11 nM) cultures and confirmed a decrease in the number of these sites in response to TCDD. The reduction in EGF binding correlated with a decrease in EGF-stimulated DNA synthesis and cell proliferation. Comparison of differentiation-competent squamous cell carcinoma (SCC) lines treated with TCDD supported an association between modulation of EGF binding and enhanced differentiation. The data indicate that basal cells are a target for TCDD. We propose that the modulation of EGF binding in basal keratinocytes by TCDD is one of the critical regulatory events resulting in enhanced differentiation.

Chloracne and chloracnegens

Chloracne, an acneform eruption resulting from poisoning by halogenated aromatic compounds, has been a considerable problem over the last 40 years. The condition is always a symptom of systemic poisoning and should be familiar to all practitioners, particularly dermatologists. It is difficult to treat and can last for long periods without known additional exposure to chloracnegens. Some chloracnegens are capable of causing a variety of systemic signs and symptoms and may be oncogenic. Although there are probably fewer than 4,000 persons with chloracne worldwide, those found with the disorder should be evaluated medically on a regular basis and followed, if possible, throughout their lives.

Problems in the assessment of human exposure to tetrachlorodibenzodioxin (TCDD): the marker chloracne

An epidemiological study, aiming to assess the extent of the exposure to tetrachlorodibenzodioxin (TCDD) of the population involved in the Seveso accident, needs an effective information system, able to answer the questions usually asked--such as: why? what? who? where? when? how long?--and therefore concerning the wide range of the expected events, from the early cases till the ones expected in the long term. The paper is concerned with evaluation of possible use of chloracne as indicator of human exposure to TCDD, taking into account from one hand chloracne itself (i.e. its latency period, sensitivity, specificity, predictive value of diagnosis, etc) and, from the other, the development of the observational process. Moreover, the paper points out the role of the dermatological findings as representative--more than and before the other clinical findings--of the exposure conditions in the polluted area. The group of subjects classified as "chloracne" by the end of the second screening (May, 1977) included 187 cases, 164 of which were children 0-14 yrs old by the 10th of July 1976; 34 out of 164 were diagnosed in September-December 1976, the other 130 were diagnosed within the screening program. The results of a survey concerning their exposure data, clinical and laboratory findings are detailed. Finally, some remarks are made related to the quality of data. The authors emphasize that the reliability of assessment of health status of the exposed population depends not only upon a comprehensive a posteriori analysis of the different sets of clinical findings, but also upon the degree of integration of the professional staffs involved at operational levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Acnegenic activity of 3-methylcholanthrene and benzo[a]pyrene, and a comparative study with 2,3,7,8-tetrachlorodibenzo-p-dioxin in the rabbit and hairless mouse

The non-halogenated hydrocarbons 3-methylcholanthrene (MC) and benzo[a]pyrene (BP) were tested for acnegenic activity using the rabbit ear test. Both compounds induced characteristics follicular hyperkeratosis, although their acnegenic potency was approximately 4 orders of magnitude lower when compared to the potent acnegen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). These results are discussed in view of the hypothesis that the acnegenic activity of TCDD and its congeners is mediated through stereospecific binding to a cytosolic receptor protein. In an experiment with hairless (hrhr) mice, which mutant has been described as an animal model for testing acnegenic potency, reduction in sebaceous gland tissue but no follicular hyperkeratosis was observed after application of a total dose of 0.4 microgram TCDD on the back skin. At a 10 times lower dose, no effects were seen. The hairless mouse strain used was responsive to TCDD as judged from the dose-related increase in the activity of aryl hydrocarbon hydroxylase (AHH) in liver microsomes, the increased liver weight and the histopathological changes in the liver. In comparison, a total dose of 0.12 microgram TCDD produced a strong follicular hyperkeratosis in the rabbit ear. From these results and from literature data, the adequacy of the hairless mouse for the testing of compounds for acnegenic potency is questioned.