Histological distinction between early allergic and irritant patch test reactions: follicular spongiosis may be characteristic of early allergic contact dermatitis

The role of eosinophils in the differential diagnosis of inflammatory skin diseases

Eosinophils are known to be present in inflammatory skin diseases, but their diagnostic utility is not well established. Upon review of the published status of lesional eosinophils, several categories were identified. 1) Lesional eosinophils highly characteristic such that, in their absence, the pathologist may question the diagnosis. These include arthropod bite reactions and scabies, urticarial dermatitis, and other eosinophilic dermatoses. 2) Lesional eosinophils rare or absent, such that, in their presence, the pathologist may question the diagnosis. These include pityriasis lichenoides, graft versus host disease, and connective tissue disorders. 3) Lesional eosinophils variable and, while in some cases expected, are not required for diagnosis. These include drug reactions, atopic dermatitis and allergic contact dermatitis. 4) Lesional eosinophils variable and not expected but may be seen to a limited extent. These include lichen planus and psoriasis.

Clinical Manifestations, Treatment, and Prevention of Acute Irritant Contact Dermatitis Caused by 2,4-Dichloro-5-Methylpyrimidine

Background

There are no reported cases of 2,4-dichloro-5-methylpyrimidine (DCP)–induced irritant contact dermatitis (ICD).

Objective

The aim of the study was to summarize the clinical features, treatment, and protective measures for DCP-induced ICD.

Methods

We retrospectively reviewed the clinical data from 64 patients with DCP-induced ICD and the protective measures in a DCP manufacturing factory.

Results

Disease onset occurred 1 to 10 minutes after DCP single exposure in all 64 patients. The contact site developed edematous erythematous skin lesions with clear boundaries. Other symptoms included a burning sensation (n = 48), pruritus (n = 16), headache (n = 4), nausea/vomiting (n = 3), and syncope (n = 1). Ten patients developed pruritic rash over the whole body 1 to 4 days after contacting DCP. Histopathologic examination of the lesions was performed in 8 patients; all 8 showed manifestations of ICD. A patch test with 1% DCP ethanol solution was performed in 7 patients. One patient withdrew because of pruritus and massive erythema over the whole body. Four patients had a strong reaction, and 2 patients had a very strong reaction. All patients were cured. Positive-pressure inflatable protective clothing protected workers from the outside environment to prevent DCP-induced ICD.

Conclusions

2,4-Dichloro-5-methylpyrimidine exposure induces acute ICD and a delayed allergic reaction in some patients (15.6%). Positive-pressure inflatable protective clothing prevents DCP-induced ICD.

Chronic Hand Eczema Guidelines From an Expert Panel of the International Eczema Council

Background

Assessment of chronic hand eczema (CHE) is complex and warrants standardization.

Objective

We sought to guide clinicians on the assessment of CHE.

Methods

An electronic questionnaire regarding the diagnosis and assessment of CHE was completed by councilors (n=45) of the International Eczema Council, an international group of clinicians and researchers with expertise in CHE. The survey consisted of 52 statements for consensus.

Results

Overall, nine statements (17.3%) had strong, twenty-three (44.2%) moderate, 12 (23.1%) low, and 8 (15.4%) very low levels of agreement. Five statements had considerable disagreement, including the value of conducting a skin biopsy (62.2% disagreement), investigating for possible type 1 reactions (60.0%), conducting a fungal culture (44.4%), finding no history of relevant allergens and/or irritants (31.1%) in most or all cases, and performing patch testing irrespective of lesion location and morphology (28.9%). Agreement was generally highest among respondents from Europe (28.6–77.8% agreement), followed by Asia (7.1%–35.7% agreement), North America (0%–35.5% agreement), and other (0%–13.3% agreement).

Conclusions

There were substantial differences of agreement, suggesting there are many knowledge and/or practice gaps with respect to CHE. Future research is needed to inform evidence-based and/or consensus guidelines for CHE.

Diagnostic utility of skin autofluorescence when patch test results are doubtful

BACKGROUND

The standard diagnostic test for allergic contact dermatitis is the patch test, which can also be used to identify irritant contact dermatitis. Doubtful reactions (?+) can be often clinically relevant to individuals and can require additional tests.

OBJECTIVES

The purpose of this study was to examine whether autofluorescence (AF) measurements in patients with doubtful reactions are helpful in diagnosing contact dermatitis.

METHODS

Patients with a history of contact dermatitis were patch tested on the upper back for 48-hours of occlusion using aqueous solutions of 5% sodium lauryl sulfate. Reaction intensity was scored, and AF was measured on reactive lesions and non-lesions. Three dermatologists classified the results as positive or negative using the fluorescence photographs of patients with a doubtful reaction.

RESULTS

Among doubtful reactions, the R/G% values were significantly higher in the AF- based positive group than in the negative group (P = .0086). On the other hand, the heterogeneity values of R, G, and B (HR, HG, HB) were significantly lower in the AF-based positive group (P = .0026, .0046, .0004 respectively).

CONCLUSIONS

Measuring AF along with the clinical readings can help confirm doubtful patch test reactions.

Review of allergic contact dermatitis: Scratching the surface

Contact dermatitis-including allergic contact dermatitis (ACD)-n and results in over four million lost work days per year in the United States alone. ACD is a classic example of a type IV delayed hypersensitivity reaction, and represents a significant burden on the health system, economy, and patient quality of life. Thorough history taking, clinical examination, histologic evaluation, and patch testing are keys to diagnosing contact dermatitis. Patch testing, especially with comprehensive and customized panels based on the patient’s exposure history, is particularly useful in identifying potential allergens in the case of allergic contact dermatitis. ACD management requires a combination of direct medical intervention, patient education, and appropriate environmental modification to prevent exposure to offending allergens in the home or workplace. Continuing advances in the study of ACD has led to an increased understanding of the disease processes, new methods for diagnosis, and improved management. This article reviews ACD-aiming to connect recent investigational data with the current clinical understanding of disease pathophysiology, diagnostic techniques, and management strategies.

Follicular contact dermatitis revisited: A review emphasizing neomycin-associated follicular contact dermatitis

Follicular contact dermatitis clinically presents as individual papules that include a central hair follicle. Pathologic features involve the follicle and the surrounding dermis: spongiosis and vesicle formation of the follicular epithelium associated with perifollicular and perivascular lymphocytic inflammation. Using the PubMed database, an extensive literature search was performed on follicular contact dermatitis and neomycin. Relevant papers were reviewed and the clinical and pathologic features, the associated chemicals (including a more detailed description of neomycin), the hypothesized pathogenesis, and the management of follicular contact dermatitis were described. Several agents-either as allergens or irritants-have been reported to elicit follicular contact dermatitis. Several hypotheses have been suggested for the selective involvement of the follicles in follicular contact dermatitis: patient allergenicity, characteristics of the agent, vehicle containing the agent, application of the agent, and external factors. The differential diagnosis of follicular contact dermatitis includes not only recurrent infundibulofolliculitis, but also drug eruption, mite infestation, viral infection, and dermatoses that affect hair follicles. The primary therapeutic intervention for follicular contact dermatitis is withdrawal of the causative agent; treatment with a topical corticosteroid preparation may also promote resolution of the dermatitis. In conclusion, follicular contact dermatitis may be secondary to allergens or irritants; topical antibiotics, including neomycin, may cause this condition. Several factors may account for the selective involvement of the hair follicle in this condition. Treatment of the dermatitis requires withdrawal of the associated topical agent; in addition, topical corticosteroids may be helpful to promote resolution of lesions.

Pathogenesis and diagnosis of contact dermatitis: Applications of reflectance confocal microscopy

Contact dermatitis (CD) is the most common professional skin disease, with frequencies ranging from 24 to 170 every 100000 individuals. Approximately 20% of the United States population suffers from CD. CD can be classified according to its origin and severity. ICD stands for irritant CD, whereas ACD means allergic CD. Their clinical presentation includes acute, sub-acute and chronic eczema. Despite their different origin, ICD and ACD often present similar clinical and histologic findings. The current gold standard for diagnosis is patch-testing. However, patch-testing is being questioned in terms of validity and reproducibility, as it relies heavily on the skill of the observer. Real-time reflectance confocal microscopy is a non-invasive imaging technique that bears strong promise for the study of CD, and it enables the evaluation of cellular and subcellular changes over time with similar resolution compared to that of conventional histology.

Follicular disorders of the face

Follicular disorders are possibly a commonly seen, though rarely reported, group of disorders, which are localized around follicles and appendages and clinically present as small papules. Classically, clinicopathological follicular plugging is seen in the "true" follicular disorders, which are appropriately referred to as follicular keratosis. Another subtype is folliculitis (infectious or noninfectious) and the follicular mimickers that clinically resemble "true" follicular disorders without the follicular keratoses. Acne vulgaris has an amalgamation of all the above lesion types. Our review is aimed at describing all the follicular disorders and gives an algorithm for diagnosing the common follicular disorders.

Patch testing: facts and controversies

The German dermatologist, Josef Jadassohn (1863-1936), first presented the results of his innovative patch-testing technique in 1895. The safety and efficacy of this diagnostic tool has stood the test of time and is still the gold standard for the diagnosis of allergic contact dermatitis (ACD). Since its discovery, much effort has been put into standardization and optimization of allergens, vehicles, and concentrations of patch-test materials; in procedures of its application; and in reading and scoring of test reactions--all contributing to the development of an accurate, reliable, and safe test with a high reproducibility of its results. Even this seemingly carved-in-stone practice, which has been used for nearly 120 years, has been questioned and challenged, engendering debates, disagreements, and controversies, which show no signs of coming to an end. Almost every step of the procedure has provoked discussions and controversies:

Abnormal epidermal barrier in the pathogenesis of contact dermatitis

A crucial role of the epidermal permeability barrier is obvious in contact dermatitis. An intact skin barrier prevents the penetration of harmful substances into the skin. Irritants and allergens that stay on the skin surface and come into contact with the stratum corneum only do not harm the skin. After disruption of the skin barrier, however, irritants may penetrate into the living epidermal layers, injure the keratinocyte membrane, and release cytokines, which leads to inflammation and to irritant contact dermatitis. The skin barrier is often disrupted by chronic exposure to water plus detergents, solvents, or other irritants. A disrupted barrier in irritant contact dermatitis also allows for the penetration of allergens. Allergens may come into contact with Langerhans and T cells, induce immunological reactions, and cause inflammation, which results in allergic contact dermatitis. Treatments in contact dermatitis should restore the skin barrier to prevent relapse of the disease. Topical corticosteroids, most often used in treating contact dermatitis, reduce immunological reactions and inflammation but do not lead to a complete barrier repair. Skin barrier repair is more complete after treatment with calcineurin inhibitors and bland lipid-based emollient; therefore, these preparations should be preferred for long-term treatment of contact dermatitis.

ROAT: morphology of ROAT on arm, neck and face in formaldehyde and diazolidinyl urea sensitive individuals

The morphology of early allergic contact dermatitis reactions was studied in formaldehyde allergic individuals exposed to a cream product preserved with 4 different concentrations of diazolidinyl urea. The study was made using a dose-escalating design in 3 different anatomical regions, the upper arm, neck and face. On the arm and neck, the dominant initial morphology was an eczematous papular eruption. In the face, the initial skin changes were more homogeneous and infiltrated erythema.

Correlation between clinical scoring of allergic patch test reactions and optical coherence tomography

Noninvasive imaging techniques might be of particular diagnostic value for studying and monitoring cutaneous inflammatory conditions such as contact dermatitis. We evaluate acute allergic contact dermatitis (AACD) by means of optical coherence tomography (OCT) and correlate the clinical grading of patch test reactions with the findings obtained from OCT. Twenty positive patch test reactions (+, n = 6; ++, n = 7; +++, n = 7) are investigated using a conventional OCT scanner. In comparison to the control sites, OCT of AACD showed pronounced skin folds, thickened and/or disrupted entrance signals, and a significant increase in epidermal thickness. Moreover, clearly demarcated signal-free cavities within the epidermis and considerable reduction of dermal reflectivity are demonstrated by OCT. Notably, the latter findings strongly correlate with the clinical patch test grading. OCT may be a useful tool for visualization of micromorphological features of AACD. However, before OCT can be employed as an objective parameter in grading severity of patch test reactions, larger studies are required that correlate clinical patch test readings and OCT findings with histopathology.

Experimental elicitation of contact allergy from a diazolidinyl urea-preserved cream in relation to anatomical region, exposure time and concentration

The elicitation potential of the cosmetic preservative diazolidinyl urea was studied in formaldehyde- and diazolidinyl urea-sensitized volunteer patients using a stepwise controlled exposure design. The test product was a facial moisturizer, preserved with varying concentrations of diazolidinyl urea, ranging from 0.05% to 0.6%. A repeated open application-like exposure test was performed on volunteers and a control group with the test product containing increasing preservative concentrations, on arm, neck and face, sequentially, for 2 weeks or until dermatitis developed. The preservative action in the cream at different test concentrations was tested in microbial challenge tests and was found effective at all concentrations tested. The study established a non-eliciting concentration of diazolidinyl urea of 0.05% in formaldehyde-sensitive patients and showed that the skin reactivity depends on the anatomical region, increasing from the upper arm to neck and, possibly, to the face. The study design, beginning on the upper arm and moving on to the neck and face seems to be relevant for the study of reactions to cosmetic products. A clear dose-response relationship was seen regarding preservative concentration in the product.

Macro-video documentation patch tests

An unequivocal distinction between allergic and irritant patch test reactions is often difficult with patch tests. This study was designed to evaluate the worth of video-macro camera documentation for differentiation between allergic and irritant test reactions and to investigate whether there are characteristic clinical differences in patch test responses between metal salts and fragrances. Patch testing was performed with nickel sulfate, fragrance mix and an irritant, sodium lauryl sulfate 1% aq., on the upper back of 82 patients, with evaluation and computer-aided video documentation after 48 and 72 hr. No reliable clinicomorphological criterion was found for assessing a weak patch test reaction as being definitely allergic. Even characteristic papules and vesicles were not regularly found in allergic reactions. However, unlike fragrance mix, patch test reactions to nickel sulfate were characteristic in that they showed a heterogeneous spread and an association with hair follicle openings, independent of reaction intensity. Evaluation based on additional computer-aided video-macro camera documentation did not add further advantage for the differentiation of allergic and irritant reactions. But well-defined clinicomorphological features and reaction patterns to single test substances or even whole substance categories could be helpful additional criteria for evaluating patch test responses in clinical practice.

Reflectance confocal microscopy may differentiate acute allergic and irritant contact dermatitis in vivo

BACKGROUND

Acute irritant contact dermatitis (ICD) and allergic contact dermatitis (ACD) may be difficult to distinguish by clinical or histologic assessment. Reflectance confocal microscopy (RCM) enables real-time, high-resolution skin imaging in vivo.

OBJECTIVE

We sought to image, characterize, and distinguish acute ACD and ICD in vivo.

METHODS

Volunteers with ACD were patch tested with an allergen and the irritant, sodium lauryl sulfate. RCM imaging and transepidermal water loss measurements were performed at 24 and 72 hours. Biopsy specimens were correlated with RCM images.

RESULTS

Spongiosis, epidermal inflammatory cell infiltrate, and vesicle formation were observed in ACD and ICD. Compared with ACD, ICD showed greater disruption of the stratum corneum, and more parakeratosis. There was a significantly greater increase in transepidermal water loss for ICD compared with ACD.

CONCLUSION

RCM is a promising tool for dynamic, noninvasive assessment and may help to differentiate acute ACD and sodium lauryl sulfate-induced ICD.

Evaluation of the histologic characteristics of patch test confirmed allergic contact dermatitis

BACKGROUND

Microscopic features of experimentally induced allergic contact dermatitis (ACD) have been reported; however, the histologic characteristics of environmentally induced ACD have not been definitively elucidated.

OBJECTIVE

This pilot study was conducted to describe the histologic features most useful in differentiating ACD from other forms of eczematous dermatitis.

METHODS

A retrospective chart review of patients who underwent evaluation for contact dermatitis was performed. The results of skin biopsy were reviewed in a blinded manner, and two subgroups were compared: gold standard ACD cases and control cases (eczematous dermatitis with negative results of patch testing).

RESULTS

Of 317 cases reviewed, 39 fulfilled the inclusion criteria. Many histologic similarities were noted: both subgroups had substantial acanthosis and lymphocytic infiltration. In addition, present to a moderate degree in both groups were hyperkeratosis, spongiosis, eosinophils, and dermal dendritic fibrohistiocytic (DFH) cells. However, compared with the control cases, eosinophilic spongiosis and multinucleate dermal DFH cells were found to a considerably greater degree in the standard ACD cases.

CONCLUSIONS

Eosinophilic spongiosis and multinucleate dermal DFH cells, in the presence of acanthosis, lymphocytic infiltrate, dermal eosinophils, and hyperkeratosis, are particularly suggestive of ACD. While such findings alone are not diagnostic of ACD, the presence of these combined histologic features supports the pursuit of patch testing in cases of chronic eczematous dermatitis.

Electrical impedance as a potential tool to distinguish between allergic and irritant contact dermatitis

BACKGROUND AND OBJECTIVE

The allergic contact reaction is a model reaction for studying the cell-mediated immune system of the skin. In this study we use a noninvasive method, electrical impedance (IMP), to compare nickel (Ni) allergic contact reactions with an irritant contact reaction induced by sodium lauryl sulfate, which has already been carefully evaluated with this method. For this purpose, we included only Ni- and sodium lauryl sulfate-induced reactions of very similar appearance.

METHODS

Various concentrations of Ni sulfate in distilled water were applied on the volar aspect of the forearms of 33 adult women who were allergic to Ni. Assessments were made using visual scoring, a new IMP technique, and transepidermal water loss 3 and 7 days later.

RESULTS

In the 19 patients who completed the study, 3 of the 4 impedance indices were significantly lower at the sodium lauryl sulfate sites than at the Ni sites on day 3; ie, the mean magnitude (MIX) (P < or = .001), imaginary part (IMAX) (P < or = .001), and real part (RIX) indices (P < or = .01). Unlike the irritant reactions, no significant increases in transepidermal water loss occurred in the allergic contact reactions. This may be because, in reactions of the studied magnitude, an allergic contact reaction does not significantly affect the epidermis because the inflammatory process is located deeper in the dermis than an irritant reaction.

CONCLUSION

This study suggests that IMP, as used herein, is suitable for distinguishing between contact reactions of allergic and irritant nature. Although pathophysiologic events in the tissue studied significantly modify impedance patterns, little is known about how to interpret the structural and chemical changes underlying these patterns. Studies are needed to determine the relation between anatomic or pathophysiologic parameters, and the findings using IMP and other established methods, such as chemical extraction and histopathology.

Vascular endothelium express CS-1 fibronectin in allergic contact dermatitis

BACKGROUND

Allergic contact dermatitis (ACD) is a common human dermatosis in which not all the mechanisms involved in its pathogenesis have been elucidated.

OBJECTIVE

To study the expression of CS-1 fibronectin, TARC and Th1-associated chemokine receptors in biopsies from allergic patch test reactions.

MATERIAL AND METHODS

Thirteen patients already diagnosed with ACD were challenged on the back with the antigen responsible of the disease and macroscopic responses and biopsies taken after 48 h. Skin biopsies from negative control challenge sites, AD and ICD were also taken. Samples were fixed, embedded in paraffin wax and processed in order to perform histological and immunohistochemical studies.

RESULTS

All subjects with ACD showed a positive clinical response and a perivascular mononuclear cell infiltration at 48 h, which was not seen in the negative controls. The majority of skin-infiltrating cells were CD4+ and CD8+ and up to 54% or 40% of them expressed CXCR3 or CCR5, respectively. We also showed expression of CS-1 fibronectin in inflamed endothelial cells not only in ACD but also in AC and ICD. In contrast TARC was only expressed in ACD and AC.

CONCLUSION

We showed for the first time that CS-1 fibronectin is expressed in dermal vessels from allergic patch tests positive reactions, as well as irritant and atopic skin lesions.

The time-dose-response relationship for elicitation of contact dermatitis in isoeugenol allergic individuals

The elicitation response in allergic contact dermatitis is dose dependent, but the time-concentration relationship for elicitation has not previously been described. In this study 27 isoeugenol-sensitive patients participated in serial dilution patch tests with isoeugenol and a double-blinded Repeated Open Application Test (ROAT) using two concentrations of isoeugenol, 0.2 and 0.05%. Seven controls without isoeugenol allergy were also included. The participants applied 3.72 +/- 1.57 (mean +/- SD) mg/cm(2) of coded isoeugenol solutions twice a day to a 3 x 3 cm(2) area on the volar aspect of the right and left arm, respectively. For each test site the applications continued until a reaction appeared or for a maximum of 28 days. The minimal criteria for a positive reaction regarded as allergic contact dermatitis was persistent erythema at the ROAT test site. All controls were negative and 16/24 (66.7%) of the included isoeugenol-sensitive subjects showed a positive ROAT to the 0.2% solution within the study period (Fisher's test, p = 0.0024). Ten of the positive patients also reacted to the 0.05% solution. The median number of days until a positive reaction to the 0.2% solution was 7 days and was 15 days for the 0.05% solution. There was a highly significant correlation between the patients' patch test threshold and the number of days until a positive ROAT. In conclusion, the time until an isoeugenol allergic individual reacts in a ROAT depends on the individual sensitivity as well as the exposure concentrations; for low concentrations of the allergen or low degree of sensitivity, the allergic contact dermatitis may develop after several weeks of exposure. Therefore, a negative ROAT after 7 days may be a false negative.