Contact dermatitis from tioconazole mimicking "one hand two feet syndrome"

Antifungal hypersensitivity reactions and cross-reactivity patterns

PURPOSE OF REVIEW

The goal of this article is to provide an updated understanding and evidence-based approach where possible for antifungal hypersensitivity. This includes recognition of clinical phenotype, implications for cross-reactivity and diagnostic, and management strategy for immediate and delayed hypersensitivity reactions.

RECENT FINDINGS

Antifungal hypersensitivity reactions can be classified according to their latency (immediate or delayed) and clinical phenotype. The majority of the cases described in the literature are delayed T-cell mediated reactions of various severities but immediate reactions consistent with non-Immunoglobulin E (IgE)-mediated mast cell activation and IgE-mediated reactions have also been described. Ancillary information such as skin testing, drug challenge and ex vivo experimental approaches can aid causality assessments and inform antifungal class cross-reactivity, which help optimize antifungal prescribing and stewardship.

SUMMARY

This review will update the clinician on mechanisms of drug hypersensitivity as well as providing a structured approach to the recognition, diagnosis and management of antifungal hypersensitivity reaction.

Two Feet-One Hand Syndrome

Ringworm infection is a common but frequently misdiagnosed skin disease. An 81-year-old woman presented with a complaint of mild itch of the third and fourth fingers of her right hand and the toes of both feet. A crusted rash was seen on the right hand and both feet. The results of potassium hydroxide testing were positive for filamentous fungi. The diagnosis of two feet-one hand syndrome was made. The rash was treated successfully by topical ketoconazole. Recognition of this typical distribution of the rash may help make a prompt diagnosis of ringworm infection.

Proposed ICDRG Classification of the Clinical Presentation of Contact Allergy

The International Contact Dermatitis Research Group proposes a classification for the clinical presentation of contact allergy. The classification is based primarily on the mode of clinical presentation. The categories are direct exposure/contact dermatitis, mimicking or exacerbation of preexisting eczema, multifactorial dermatitis including allergic contact dermatitis, by proxy, mimicking angioedema, airborne contact dermatitis, photo-induced contact dermatitis, systemic contact dermatitis, noneczematous contact dermatitis, contact urticaria, protein contact dermatitis, respiratory/mucosal symptoms, oral contact dermatitis, erythroderma/exfoliative dermatitis, minor forms of presentation, and extracutaneous manifestations.

Contact Dermatitis Mimickers: A Tertiary Care Center's Experience

Background:

Contact dermatitis (CD) is very common but can be mimicked by numerous dermatologic conditions. Thus, a wide differential must be considered before a definitive diagnosis of CD is made to ensure the patient receives appropriate treatment and follow-up.

Objective:

To describe conditions that can present similarly to contact dermatitis.

Methods:

We retrospectively analyzed patients referred to the Occupational Disease Specialized Program at St. Michael's Hospital in Toronto between 2009 and 2011 for CD investigations but with a final diagnosis other than CD.

Results:

We report cases of 2 feet-1 hand syndrome, Dermatitis Herpetiformis, Sézary syndrome and two cases of Pityriasis Rubra Pilaris misdiagnosed as CD and referred for patch testing at our busy tertiary care centre. Failing to recognize these mimickers of CD resulted in a significant delay in diagnosis for the patients and resulting initiation of necessary intervention.

Conclusions:

It is important to consider numerous mimickers before making a diagnosis of CD to ensure optimal outcome for patients.

A study of 72 patients with contact allergy to tioconazole

Over a 3 1/2 year period, from 1991 to 1994, we detected contact allergy to tioconazole in 72 patients by epicutaneous testing. During this period, tioconazole was included in the standard series of epicutaneous tests. Except for the first 6 months, the incidence of positive patch test reactions to tioconazole was over 1% of patients tested for contact allergy. As well as those tested with the standard series, 18 additional patients with tioconazole allergy were detected by direct testing with an imidazole patch test series. Of the various imidazole derivatives, tioconazole was the most important contact allergen. About half of patients with contact hypersensitivity to tioconazole, had additional contact allergies detected by the standard series. Men and women were equally affected. The present study suggests that tioconazole is an important contact allergen, which should be included into the patch test series in countries where it is used as a topical antifungal agent.

Contact allergy to imidazoles used as antimycotic agents

The present article reviews the literature (up to 1994) on contact sensitivity to imidazoles and presents the results obtained from 15 patients observed at the Contact Allergy Unit in Leuven. The frequency as well as the cross-reaction patterns described are analyzed. Although allergic contact reactions may have been missed in the past (mainly because of problems with the correct choice of vehicle for patch testing), they seem to be relatively infrequent in view of their widespread use. The imidazole derivatives most frequently reported to be allergens are miconazole, econazole, tioconazole, and isoconazole. As far as cross-reactivity is concerned, statistically significant associations were found in the patient data between miconazole, econazole, and isoconazole; between sulconazole, miconazole, and econazole; and also between isoconazole and tioconazole. Patients sensitive to phenylethyl imidazoles (except ketoconazole) needing antimycotic therapy should be advised to use ketoconazole, clotrimazole, bifonazole, or, perhaps, the new flutrimazole. Clearly, non-imidazole antifungals can also be used.