Black-spot poison ivy, a report of 3 cases with clinicopathologic correlation

INTRODUCTION Black-spot poison ivy is an uncommon clinical manifestation of contact with Toxicodendron plants. Unlike allergic contact dermatitis, which typically manifests in sensitized individuals within 2448 hours, the black lacquer that results from oxidation of the oleoresin after contact with the plant develops within hours of exposure and precedes allergic contact dermatitis, in some cases by weeks. Black-spots are usually accompanied by an irritant dermatitis reaction of varying severity. The appearance of an irregular black macule is often alarming to patients and prompts clinical evaluation. Because the diagnosis is straightforward and based on clinical appearance and history alone, biopsy is rarely done; thus, few descriptions of the pathologic findings exist in the literature. We herein report 3 characteristic cases of black-spot poison ivy with clinicopathologic correlation and review the pathophysiology of this uncommon condition.