Faculty Bibliography

BACKGROUND:Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) allergy has increased for the last decade, mostly not only because of high concentrations in cosmetics but also because of its use as a biocide in industrial settings. OBJECTIVE:We report an outbreak of allergic contact dermatitis in 8 workers at a water bottling plant secondary to excess levels of MCI/MI in the cooling system, found to be at levels 5 times the manufacturer's recommendations. METHODS:Of 15 workers in the plastic bottle manufacturing area, 8 developed dermatitis, and 4 were referred for patch testing using a 100-allergen panel applied and interpreted in the standardized method according to the North American Contact Dermatitis Group. RESULTS:Four workers had a positive reaction to MCI/MI. An investigation at the plant revealed that the concentration of MCI/MI was 365 ppm. The manufacturer's recommended level was 48 ppm. The cooling system was subsequently flushed, and biocide levels decreased to recommended levels. Afterward, all the affected workers experienced clearance of their allergic contact dermatitis. CONCLUSIONS:Occupational sensitization to MCI/MI is on the rise, in this instance, because of excess levels in the cooling system. Our findings demonstrate the continued need for awareness of the allergenicity of this preservative in the occupational setting.

This article provides an overview of the evaluation and management of occupational contact dermatitis, including how to evaluate a patient with suspected occupational contact dermatitis. Patch testing, how to perform a site visit, and how to properly manage using preventative measures, prescribed therapies, and patient education are discussed.

BACKGROUND:Syphilis is often misdiagnosed clinically, and biopsies might be required. OBJECTIVE:To determine histopathologic features that distinguish secondary syphilis from pityriasis lichenoides (PL), pityriasis rosea (PR), and early mycosis fungoides (MF). METHODS:Histopathologic features of 100 cases of syphilis, 110 cases of PL, 72 cases of PR, and 101 cases of MF were compared. RESULTS:Elongated rete ridges and interstitial inflammation favor syphilis over PL (likelihood ratios 3.44 and 2.72, respectively), but no feature reliably distinguishes between them. Secondary syphilis and PR can be distinguished by neutrophils in the stratum corneum, plasma cells, interface dermatitis with lymphocytes and vacuoles, and lymphocytes with ample cytoplasm. Plasma cells and lymphocytes with ample cytoplasm are rare in early MF and can be used as distinguishing features. CONCLUSIONS:Histopathologic features characteristic of syphilis can be seen in PL, PR, and early MF. Distinguishing syphilis from PL can be difficult histologically, and a high index of suspicion is required. Although elongation of rete and interstitial inflammation favor syphilis, plasma cells (historically considered a significant feature of syphilis) are often encountered in PL. Vacuolar interface dermatitis with a lymphocyte in every vacuole is considered characteristic of PL, but this feature appears to be more common in syphilis.

The prevalence of occupational contact dermatitis is estimated to be between 6.7% and 10.6% and can lead to missed work and job loss. Although treatment may provide temporary relief, identifying the culprit allergen may help the clinician counsel on how to avoid or reduce exposure. Some of the most common high-risk occupations for allergic contact dermatitis include agricultural workers, construction workers, health care workers, hairdressers, mechanics, and machinists. In this article, we discuss the common occupational exposures of these high-risk professions, and summarize the common culprit allergens.