Perianal Dermatitis.

Background: Perianal complaints are often consulted in dermatology clinics, and in many cases, a conclusive diagnosis is not easily made.

Objective: The aim of this study was to study and identify the epidemiological, clinical, and contact allergy features of patients with perianal dermatitis who attended at a contact dermatitis unit in a tertiary hospital in Spain.

Methods: Adult patients with long-lasting (>4 weeks) perianal dermatitis were recruited during the past 10 years for investigation and follow-up. Every patient underwent a diagnostic workup consisting of dermatological exploration and patch tests with the standard and specific series, as well as the patients' own products. General surgical exploration was also performed in some patients.

Results: One hundred twenty-four patients were included. The MOAHLFA index was as follows: 43.5, 0, 4.8, 11.3, 1.6, 8.1, and 75. The main final diagnoses were allergic contact dermatitis (32.3%), psoriasis (24.2%), irritant contact dermatitis (17.7%), and lichen simplex (neurodermatitis) (10%). Eighty-one patients (66.1%) showed 1 or more positive reactions, and in 52 patients (43%), positive reactions relevant to the present disease were found.

Conclusions: Contact allergy in patients with long-lasting perianal complaints is frequent. It is mandatory for these patients to be referred to a dermatologist for an adequate evaluation and patch testing. Methylchloroisothiazolinone/methylisothiazolinone seems as the most common allergen implicated in perianal contact dermatitis.