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False-positive "poral" cobalt patch test reactions reside in the eccrine acrosyringium.
1Department of Dermatology (L468), Oregon Health Sciences University, Portland 97201-3098, USA.
Cutis
|February 9, 2000
Summary
Cobalt patch testing revealed irritant reactions in 32% of patients. These "poral" reactions, distinct from allergic contact dermatitis, suggest a toxic effect of cobalt on the acrosyringium.
Area of Science:
- Dermatology
- Toxicology
- Histopathology
Background:
- Cobalt is a metal used in various industries.
- Contact dermatitis is a common skin condition.
- Distinguishing irritant from allergic reactions is crucial for diagnosis.
Purpose of the Study:
- To investigate the nature of irritant reactions to cobalt observed during patch testing.
- To describe the unique histopathological features of these reactions.
- To differentiate these reactions from allergic contact dermatitis.
Main Methods:
- Patch testing of 222 patients in a contact dermatitis clinic (1993-1995).
- Detailed clinical observation of reactions to cobalt.
- Histopathological examination of skin biopsies from affected sites.
Main Results:
- Seventy (32%) of 222 patients exhibited irritant reactions to cobalt.
- Reactions were characterized as "poral", affecting the acrosyringium.
- Histopathology confirmed these reactions are neither follicular nor petechial and appear non-allergic.
Conclusions:
- Cobalt can induce unique "poral" irritant reactions.
- These reactions likely result from a direct toxic effect of cobalt on the acrosyringium.
- The findings aid in differentiating irritant cobalt reactions from allergic contact dermatitis.