Allergic Contact Dermatitis Patients Research Articles

Machine Learning in Allergic Contact Dermatitis: Identifying (Dis)similarities between Polysensitized and Monosensitized Patients

Background: Allergic contact dermatitis (ACD) is a delayed hypersensitivity reaction occurring in sensitized individuals due to exposure to allergens. Polysensitization, defined as positive reactions to multiple unrelated haptens, increases the risk of ACD development and affects patients’ quality of life. The aim of this study is to apply machine learning in order to analyze the association between ACD, polysensitization, individual susceptibility, and patients’ characteristics. Methods: Patch test results and demographics from 400 ACD patients (Study protocol Nr. 3765/2022), categorized as polysensitized or monosensitized, were analyzed. Classic statistical analysis and multiple correspondence analysis (MCA) were utilized to explore relationships among variables. Results: The findings revealed significant associations between patient characteristics and ACD patterns, with hand dermatitis showing the strongest correlation. MCA provided insights into the complex interplay of demographic and clinical factors influencing ACD prevalence. Conclusion: Overall, this study highlights the potential of machine learning in unveiling hidden patterns within dermatological data, paving the way for future advancements in the field.

Comparison of patch test positivity after 24 and 48 hours of occlusion time in patients of allergic contact dermatitis: A prospective study.

Patch test is the gold standard for diagnosing allergic contact dermatitis. Conventionally, the patches are applied for 48 h, which in tropical weather conditions causes excessive sweating, leading to irritation, and sometimes the patches come off, making the test inconclusive. To compare the patch test positivity after 24 and 48 h of occlusion time in patients of allergic contact dermatitis, using standard allergen concentration. Clinically suspected patients of allergic contact dermatitis were enrolled and patch tested using the Indian Standard Series, parthenium acetone extracts (1:50, 1:100 and 1:200 dilutions) and patient material. Patches were applied in duplicate on either side of the back, using a random number table. One set of patches was removed after 24-h of occlusion, while the other set after 48-h. Readings were performed at 48- and 96-h by two independent dermatologists, blinded to the duration of occlusion. The study had 97 adult patients (58 males and 39 females; mean age: 48.12 ± 13.07 years). A total of 133 and 142 positive reactions were observed after 48 h occlusion at 48 and 96 h reading, respectively. Of these 117 (87.9%) and 132 (92.9%) patches were positive and concordant and noted at 24 h occlusion time. The Cohen's kappa coefficient were 0.94 for 48 h and 0.97 for 96 h reading, hence showing an almost complete agreement (ⱪ > 0.81) between patches occluded for 24 and 48 h. Though there is no significant difference in patch test positivity among ISS allergens after either occlusion time, 48 h occlusion performs significantly better compared with 24 h, when reactions of all allergens (ISS, patient material and parthenium acetone extract) are analysed together.

Overcoming False-Negative Patch Tests: A Systematic Literature Review.

Exogenous allergens, found in cosmetic products, jewelry items, antiseptics and antibacterials, plants, and solvents, can cause clinical allergic contact dermatitis (ACD). To help identify and discern which allergen is causing ACD, clinicians use patch tests, but they can yield false-negative results at times. Examining potential reasoning for false negatives is particularly helpful when a patient's history and physical examination strongly suggest ACD, and the patch test is negative. A strong history and physical presentation suggestive of ACD warrants additional patch testing or other methods to verify a false-negative patch test result. We conducted a literature review to compile various reasonings and solutions for false-negative patch tests in suspected ACD patients. Utilizing EMBASE, Scopus, PubMed, and Google Scholars, 49 articles were included by using search terms such as "False negative patch test" or "False-negative patch test" and "allergic contact dermatitis," or "ACD." Common factors that led to false-negative patch test results include low allergen concentration, inadequate percutaneous penetration, technique error, immunosuppressive therapy, and ultraviolet exposure. Potential solutions include using different vehicles, concentration, increasing reading time, repeating the patch test, intradermal testing, and repeat open application testing. If a false-negative patch test is suspected, then intradermal testing can be administered to ensure the specificity of the patch test result. Considering the main contributing factors and solutions to false-negative patch tests, clinicians can accurately diagnose ACD and administer proper treatment plans.

Clinical features of allergic contact dermatitis to sandals: a case series

Background: Allergic contact dermatitis (ACD) is a skin inflammation caused by a type 4 delayed-type hypersensitivity reaction. One of the most common types of ACD is shoe dermatitis, characterized by pruritic or painful bilateral and symmetrical erythema, papules, vesicles, scaling, crusting, lichenification, or fissures at the site of footwear contact. Case series: We present seven patients with allergic contact dermatitis caused by rubber flip-flop sandals who presented with acute to chronic eczema and leukoderma. Patients range in age from 4 to 65 years old, with symptoms lasting from 5 months to 2 years. Two of the seven patients had a history of atopy. Conclusion: Flip-flop sandals are the most common offending footwear in Indonesian ACD patients because they are appropriate and comfortable in hot and humid climates like Indonesia. Rubber and rubber chemicals, preservatives, shoe adhesives, and leather materials are the most common offending allergens.

Contact allergy in atopic dermatitis: A prospective study on prevalence, incriminated allergens and clinical insights.

The relationship between atopic dermatitis (AD) and allergic contact dermatitis (ACD) is a matter of debate. The purpose of our study is to assess the frequency of ACD in patients with AD, the incriminated allergens and the potential risk factors. This is a prospective study, including cases of AD diagnosed based on Hanifin and Rajka's criteria. All patients were patch tested to the European baseline series and corticosteroid series. Ninety-three patients were included. Fifty-six patients (60.2%) had positive patch test results of which 71.4% were relevant. The most frequent allergens were: textile dye mix (24.7%), nickel (20.4%), cobalt (12.9%), isothiazolinone (8.6%), quanterium 15 (4.3%) and balsam of Peru (4.3%). Chromium, fragrance mix I, fragrance mix II and PTBP were positive in three cases (3.2%). Two cases of allergy to corticoids were identified. Facial involvement and duration of AD were significantly associated with contact sensitization (p = 0.04 and p = 0.005, respectively). Avoidance of relevant allergens resulted in a statistically significant decrease in SCORAD (p < 0.001). ACD remains an important co-morbidity of AD. We observed a high frequency of ACD to textile dyes, isothiazolinones and fragrances. Avoidance of relevant allergens has resulted in an improvement of patients' skin symptoms.

What Is the Role of Allergic Contact Dermatitis in Patients with Lower Leg Ulcers?

To analyze the relationship between contact dermatitis and delayed wound healing, discuss the diagnosis and treatment of lower leg contact dermatitis, and provide an algorithm for the patient with a red leg and delayed wound healing. This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care. After participating in this educational activity, the participant will:1. Describe the nature of contact dermatitis.2. Distinguish between allergic and irritant contact dermatitis and the other major differential diagnoses of delayed wound healing in this clinical scenario.3. Outline the steps in the diagnosis of allergic contact dermatitis and irritant contact dermatitis and identify common haptens responsible for allergic contact dermatitis in patients with venous leg ulcers.4. Apply the algorithm for delayed wound healing on a background of lower leg dermatitis.

What Is the Role of Allergic Contact Dermatitis in Patients with Lower Leg Ulcers?

What Is the Role of Allergic Contact Dermatitis in Patients with Lower Leg Ulcers?

CD11 Patch testing in vulval dermatoses

Abstract Patch testing is an important tool in the investigation of patients with vulval dermatoses, with a significant impact on patients with a relevant identifiable allergen. There has been little research conducted in this area, with small studies suggesting a higher rate of positivity in anogenital dermatoses (39–78%) vs. patch testing in female patients generally (35–40%) (Woodruff CM, Trivedi MK, Botto N, Kornik R. Allergic contact dermatitis of the vulva. Dermatitis 2018; 29:233–43). There is also a high rate of clinically relevant results (13–49%) (Vandeweege S, Debaene B, Lapeere H, Verstraelen H. A systematic review of allergic and irritative contact dermatitis of the vulva: the most important allergens/irritants and the role of patch testing. Contact Dermatitis 2023; 88:249–62). The aetiology of this increased rate of allergic dermatitis at this site can be attributed to a number of factors. This includes intrinsic immunological characteristics of the vulval skin, local elements including infection and urine exposure, as well as external behavioural factors. There is a lack of site-specific guidance in light of this propensity of allergic contact dermatitis in vulval dermatoses. This review examined 54 patient records retrospectively at the University Hospital North Durham from 2016 to 2021 and prospectively from July to December 2022 referred for patch testing with vulval symptoms. Forty-eight patients were included with an average age of 51 years. Itch (48%) and discomfort or soreness (28%) were the main symptoms for which patients were referred. The most frequently requested patch test batteries after the British Standard Battery were medicaments, then cortico­st­eroid. The overall positivity of this cohort was 73%, in line with the available literature. The most common allergens were nickel, followed by fragrances. Of the patients with positive patch tests, 48% were relevant. Forty per cent had a partial response on withdrawal of the allergen, and 8% had complete response. Given the psychosocial impact of vulval pruritus and discomfort and the high positivity of patch testing in these patients, further population-based research is warranted to standardize patch testing in vulval dermatoses. Additionally, a low threshold for referral for patch testing should be considered to identify any element of allergic contact dermatitis in patients with recalcitrant vulval symptoms.

Rosmarinic acid ameliorates skin inflammation and pruritus in allergic contact dermatitis by inhibiting mast cell-mediated MRGPRX2/PLCγ1 signaling pathway.

Allergic contact dermatitis (ACD) is one of the most common dermatoses, which has high disease burden and quality of life impairment. Anti-histamine is not effective in a part of the ACD patients. Thus, the discovery of novel antipruritic therapy is of highly demand. In this study, we investigated the anti-pruritic effects of rosmarinic acid (RA) and explored the underlying mechanism. SPF Balb/c mice were randomly divided into control group, ACD model group, RA group (1.0mg/kg) and loratadine (LORA) group (1.5mg/kg). Back epidermal thickness was recorded. H&E staining was used for pathological observation. Mast cell degranulation was assessed by toluidine blue staining. ELISA assay was employed to detect cytokines levels. Cortistatin-14 (CST-14) and Mas-related G protein-coupled receptor X2 (MRGPRX2) expression was detetcted by RT-PCR and western blot. Molecular docking assay was used to predict the affinity of RA and MRGPRX2. Surface plasmon resonance (SPR) assay was used to verify structure affinity of RA and MRGPRX2. RA treatment significantly decreased epidermal keratinization and inflammatory cell infiltration in ACD mouse model. Administration of RA significantly reduced secretion of histamine, IL-13, and mRNA expression of CST-14. Furthermore, RA treatment increased mRNA expression of MRGPRX2. In addition, Molecular docking results predict that RA has a good affinity with MRGPRX2. RA displayed a structure affinity (KD=8.89×10-4) with MRGPRX2 by SPR. RA inhibited CST-14 and Compound 48/80 (C48/80)-induced mast cell activation via MRGPRX2-PLCγ1-PKC-NF-κB signaling pathway. RA exhibits anti-pruritic and anti-inflammatory effects in ACD mice by inhibiting MRGPRX2-PLCγ1-PKC-NF-κB signaling pathway. RA might emerge as a potential drug for the treatment of pruritus and skin inflammation in the setting of ACD.

Allergic Contact Dermatitis and Patch Testing in Skin of Color Patients.

Objective: Skin of color patients face important health issues relevant to dermatologists, such as allergic contact dermatitis; however, there is a lack of information surrounding common allergens causing contact dermatitis that disproportionately affect skin of color patients, as well as interpreting patch testing in this population. Methods: Covidence, Embase, MEDLINE, PubMed, Web of Science, and Google Scholar were searched to identify relevant articles studying allergic and irritant contact dermatitis in skin of color patients. Results: The most common positive reactions in African American patients included PPD, balsam of Peru, bacitracin, fragrance mix, and nickel. The most common positive reactions in Hispanic patients included Carba mix, nickel sulfate, and thiuram mix. The most common positive reactions in Asian patients included nickel sulfate, fragrance mix, and potassium dichromate. When interpreting patch test results in patients with higher Fitzpatrick skin types, positive patch tests presented with lichenification and hyperpigmentation, rather than erythema and vesicles. Furthermore, characteristic bright red or pink hues for positive results may appear violaceous or faint pink. Conclusions: Awareness of the common allergens associated with allergic contact dermatitis in patients of skin of color can help guide patch testing as an important diagnostic tool. Further research must be conducted regarding contact dermatitis in this patient population, especially given the relative lack of data surrounding Hispanic, Asian and Pacific Islander, and Native American patients.

Analysis of Positive Patch Test Allergens in Allergic Contact Dermatitis Patients with Atopic Dermatitis.

There has been debate regarding whether patients with atopic dermatitis (AD) have an altered frequency of contact allergen sensitization. Increased exposure to topical medications and moisturizers as well as impaired skin barrier function increase the risk of contact sensitization, whereas the Th2-skewed inflammatory pathway of AD is associated with a reduced risk. This retrospective study was performed to determine the characteristics of contact sensitization in allergic contact dermatitis (ACD) patients with a current or past history of AD. A clinical record review was conducted for patients referred to Ewha Womans University Medical Center, for patch tests between March 2017 and March 2021. We compared the rates of contact sensitization between ACD patients with and without AD. In total, 515 patch test results were reviewed and divided into the AD group (n=53) and non-AD group (n=462). The AD group showed decreased any-allergen positivity (1+, 2+, or 3+) (56.6%) compared to the non-AD group (72.9%) (p=0.013). The positivity rate for budesonide was significantly higher in the AD group (p=0.011), while the prevalence of a positive result for balsam of Peru was higher in the non-AD group (p=0.036). Nickel sulfate, cobalt chloride, and potassium dichromate were the most common sensitized allergens in both groups. Our study shows a decreased prevalence of contact sensitization in AD patients compared to non-AD patients. Clinicians should be aware of the risk of corticosteroid allergies in ACD patients with history of AD.

Translated article] Contact Allergy in Patients With Rosacea

Background and objectiveRosacea is a chronic acneiform skin disorder in which impaired skin barrier function can lead to sensitization to allergens. We aimed to analyze contact allergies in our patients with rosacea. Material and methodsRetrospective cohort study of all patients who underwent patch testing in our skin allergy clinic between May 1991 and May 2019. ResultsA total of 200 patients with rosacea were referred to our clinic for patch testing during the study period; they represented 2.1% of all patch tested patients in the period. Eighty-one percent were women (mean age, 44.7years). At least 1 positive patch test was recorded for 46.5%; 15% were of current relevance. The most frequent positive reaction was to nickel (26%), followed by cobalt chloride (6.5%), isothiazolinones (6%), p-phenylenediamine (5.5%), fragrance mix II (5%), and thimerosal (3.5%). The most common currently relevant patch test reactions were to isothiazolinones in 10 of the 200 patients (5%); to phenylenediamine, fragrance mix II, and toluensulfonamide formaldehyde resin in 4 patients (2%) each; and to tixocortol and fragrance mix I in 2 patients (1%) each. The allergen groups most often implicated were metals (of current relevance in 12.6%) and drugs (of current relevance in 25.8%). Preservatives and fragrances were the next most common allergen groups, and 70.8% and 43.7% of the positive reactions in these groups, respectively, were of current relevance. Cosmetics were the most frequent source of sensitization, followed by topical medications—notably corticosteroids and antifungal agents. ConclusionsWe emphasize the high prevalence of allergic contact dermatitis in patients with rosacea, a finding which supports patch testing, especially if eruptions worsen when these patients use cosmetics and topical medications.

Sensibilización alérgica de contacto en pacientes con rosácea

Background and objectiveRosacea is a chronic acneiform skin disorder in which impaired skin barrier function can lead to sensitization to allergens. We aimed to analyze contact allergies in our patients with rosacea. Material and methodsRetrospective cohort study of all patients who underwent patch testing in our skin allergy clinic between May 1991 and May 2019. ResultsA total of 200 patients with rosacea were referred to our clinic for patch testing during the study period; they represented 2.1% of all patch tested patients in the period. Eighty-one percent were women (mean age, 44.7years). At least 1positive patch test was recorded for 46.5%; 15% were of current relevance. The most frequent positive reaction was to nickel (26%), followed by cobalt chloride (6.5%), isothiazolinones (6%), p-phenylenediamine (5.5%), fragrance mixII (5%), and thimerosal (3.5%). The most common currently relevant patch test reactions were to isothiazolinones in 10 of the 200 patients (5%); to phenylenediamine, fragrance mixII, and toluensulfonamide formaldehyde resin in 4 patients (2%) each; and to tixocortol and fragrance mixI in 2 patients (1%) each. The allergen groups most often implicated were metals (of current relevance in 12.6%) and drugs (of current relevance in 25.8%). Preservatives and fragrances were the next most common allergen groups, and 70.8% and 43.7% of the positive reactions in these groups, respectively, were of current relevance. Cosmetics were the most frequent source of sensitization, followed by topical medications — notably corticosteroids and antifungal agents. ConclusionsWe emphasize the high prevalence of allergic contact dermatitis in patients with rosacea, a finding which supports patch testing, especially if eruptions worsen when these patients use cosmetics and topical medications.

Allergic rhinitis, allergic contact dermatitis and disease comorbidity belong to separate entities with distinct composition of T-cell subsets, cytokines, immunoglobulins and autoantibodies

BackgroundAllergic rhinitis (AR) and allergic contact dermatitis (ACD) are prevalent allergic diseases and have significant impacts on patients’ daily life. Despite many studies on AR or ACD have been conducted separately, little is known about the immune responses in patients of AR combined with ACD and the interplay between AR and ACD. Our study compared various aspects of immune elements in patients with AR or/and ACD, aiming to characterize the immune responses in AR, ACD, and AR combined with ACD.MethodsA total of 57 patients diagnosed with AR or/and ACD and 28 healthy volunteers were included. AR patients were further divided into seasonal AR (SAR) and perennial AR (PAR). All subjects’ blood samples were taken to assess the concentration of immunoglobulins, complement C3, C4, autoantibodies and cytokines in serum by immunoturbidimetry, ELISA or Luminex200 platform. Peripheral blood mononuclear cells (PBMCs) were subjected to the analysis of lymphocyte subpopulations by flow cytometry.ResultsIt indicated that AR disease caused elevated levels of IgE, IgA, IgG, IgG4, as well as IL-4, IL-15, IL-8 and IL-6 in serum. AR patients possessed a decreased CD4/CD8 ratio and an increased proportion of memory CD4 + T-cell subset, with a skewed Th2 response and an enhanced CD8 + T-cell activation. Compared with patients with sole AR or ACD condition, AR + ACD patients presented with a significantly increased proportion of memory CD8 + T-cell subset and were prone to autoimmune disorders as indicated by the increased autoantibodies. The immune elements in patients with ACD only were least affected compared with those in other conditions. Additionally, seasonal or perennial AR patients exhibited different cytokine profiles and proportions of memory T-cell subsets.ConclusionsIn this study, we illuminated the respective characteristics of immune responses in AR, ACD, and AR combined with ACD. Meanwhile, we discovered that the PAR and SAR patients possessed different cytokine profiles and T-cell compartments. It suggested that these allergic conditions belong to different disease entities. Characterizing the detailed immune changes in these allergic diseases would help to develop proper treatments targeting particular immune elements in different allergic diseases.

Keratin 17 Promotes T Cell Response in Allergic Contact Dermatitis by Upregulating C-C Motif Chemokine Ligand 20.

Allergic contact dermatitis (ACD) is a delayed-type hypersensitivity response to skin contact allergens in which keratinocytes are critical in the initiation of early responses. Keratin 17 (K17) is a cytoskeletal protein inducible under stressful conditions and regulates multiple cellular processes, especially in skin inflammatory diseases; however, knowledge regarding its contribution to ACD pathogenesis remains ill defined. In the present study, we clarified the proinflammatory role of K17 in an oxazolone (OXA)-induced contact hypersensitivity (CHS) murine model and identified the underlying molecular mechanisms. Our results showed that K17 was highly expressed in the lesional skin of ACD patients and OXA-induced CHS mice. Mice lacking K17 exhibited alleviated OXA-induced skin inflammation, including milder ear swelling, a reduced frequency of T cell infiltration, and decreased inflammatory cytokine levels. In vitro, K17 stimulated and activated human keratinocytes to produce plenty of proinflammatory mediators, especially the chemokine CCL20, and promoted keratinocyte-mediated T cell trafficking. The neutralization of CCL20 with a CCL20-neutralizing monoclonal antibody significantly alleviated OXA-induced skin inflammation in vivo. Moreover, K17 could translocate into the nucleus of activated keratinocytes through a process dependent on the nuclear-localization signal (NLS) and nuclear-export signal (NES) sequences, thus facilitating the activation and nuclear translocation of signal transducer and activator of transcription 3 (STAT3), further promoting the production of CCL20 and T cell trafficking to the lesional skin. Taken together, these results highlight the novel roles of K17 in driving allergen-induced skin inflammation and suggest targeting K17 as a potential strategy for ACD.

Prevalence and trend of allergen sensitization in patients with a diagnosis of stasis dermatitis referred for patch testing, North American contact dermatitis group data, 2001-2016.

Few studies explored the relationship between stasis dermatitis (SD) and allergic contact dermatitis (ACD). To examine trends, associations, and clinical relevance of ACD in patients referred for patch testing who had a final SD diagnosis. Retrospective analysis from 2001 to 2016 of 38,723 patients from the North American Contact Dermatitis Group. After patch testing, 303 (0.7%) patients were diagnosed with SD; 46.7% had a concomitant diagnosis of ACD. Patients with vs. without a final SD diagnosis had similar proportions of ≥ 1 positive allergic reaction (59.7% vs. 64.7%; Chi-square, P = 0.0724) but higher odds of allergic reactions to fragrance mix I, bacitracin, quaternium-15, Myroxylon pereirae, benzalkonium chloride, ethyleneurea melamine formaldehyde, diazolidinyl urea, and propylene glycol. The most commonly relevant allergens in patients with final SD diagnosis were fragrance mix I, Myroxylon pereirae, bacitracin, quaternium-15, and formaldehyde. The most common allergen sources were personal care products, topical medications and other health aid products. Nearly half of patients with a final SD diagnosis were also diagnosed with ACD, supporting the role of patch testing in select SD patients.

Changes in Product Use and Quality of Life After Patch Testing in Children With Allergic Contact Dermatitis: A Follow-up Survey.

Patch testing is the standard to diagnose allergic contact dermatitis (ACD). This study assessed the value of patch testing for product changes and quality of life in children with ACD. In this cross-sectional survey, we used a questionnaire to follow up with families of ACD patients about changes since patch testing and counseling preferences. Eligible participants were 18 years or younger during expanded series or personalized patch tests at the Washington University School of Medicine from 2007 to 2020. Of the 43 enrolled participants, most were positive for multiple allergens (63%) and changed personal products after patch testing (71%). Only 26% of the families consistently read product labels before patch testing, compared with 66% after. Patients saw a mean relative reduction of 49% in severity of rash (8.2-4.2 of 10), 46% in interference with activities (5.7-3.1), and 51% in self-consciousness (7.0-3.4) since patch testing. Families gave favorable feedback for counseling on products to avoid (9.4 of 10 average rating of usefulness), product recommendations (8.5 of 10), and chemical names (7.9 of 10). Patch testing can lead to meaningful improvements in quality of life for most children with ACD. Counseling related to positive patch test results should include discussion of specific products to use and avoid.

Patch testing results in skin of color: A retrospective review from the Massachusetts General Hospital contact dermatitis clinic

Patch testing results in skin of color: A retrospective review from the Massachusetts General Hospital contact dermatitis clinic

Allergic Contact Dermatitis in Patients with Atopic Dermatitis

Allergic Contact Dermatitis in Patients with Atopic Dermatitis

Paraphenylenediamine and related chemicals as allergens responsible for allergic contact dermatitis.

IntroductionParaphenylenediamine (PPDA) is a chemical with strong sensitizing properties used for dyeing of hair and textiles. Paraphenylenediamine can cross-react, resulting in allergy to other related compounds. The prevalence of PPDA sensitization varies widely. The objectives were to assess the frequency of positive patch test reactions to PPDA and related chemicals among patients with allergic contact dermatitis (ACD) and to analyze them regarding their clinical pattern, occupation and cross-reactions.Material and methodsThe sociodemographic and clinical data of patients with positive patch tests to PPDA, N-isopropyl-N-phenyl-4-phenylenediamine (IPPD), ethylenediamine (EDA), triethylenetetramine (TETA) and toluene-2,5-diamine (TDA) were analyzed. The frequency, strength and cross-reactions with other chemicals were assessed.ResultsOf 4087 ACD patients patch-tested between 2006 and 2015, positive reactions to PPDA and other amines were found in 166 (4.1%). The occupational character of PPDA allergy was established in 34.3% of patients. Personal history of atopy was reported by 36.7% of patients. In 98% of those examined, allergy presented as ACD, most frequently affecting hands. Hypersensitivity to PPDA was diagnosed in 77.1%, to IPPD in 20.5%, to TDA in 6%, to TETA in 1.2%, and to EDA in 0.6% of cases. The patients with an extremely strong PPDA reaction significantly more frequently showed reactions to other para group chemicals, especially to benzocaine.ConclusionsParaphenylenediamine was a major cause of contact allergy of diverse clinical picture more often affecting women, especially with atopy. Every fifth PPDA-allergic person exhibited hypersensitivity to other related compounds. Strong reactions to PPDA increased the risk of cross-reactions.