Methylchloroisothiazolinone/methylisothiazolinone and methylisothiazolinone allergies can be detected by 200 ppm of methylchloroisothiazolinone/methylisothiazolinone patch test concentration.

Background: Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and methylisothiazolinone (MI) contact allergies are rising dramatically. Moreover, 100 ppm of MCI/MI patch test might not detect an important number of MCI/MI and MI allergies.

Objectives: This study aimed to present the prevalence of contact allergy to both preservatives in an area of Spain and to investigate if 100 ppm of MCI/MI is an adequate concentration for a proper diagnosis.

Multiple eruptive keratoacanthomas associated with leflunomide.

A 78-year-old woman diagnosed with rheumatoid arthritis without a history of skin tumors or immunosuppressive medication, started treatment with leflunomide. One month after the introduction of the drug, and for two consecutive years, she developed multiple crateriform nodules and papules on her lower extremities . Biopsy specimens showed keratoacanthomas and squamous-cell carcinomas.