Contact allergy to a cocobolo bracelet.

Tropical woods are highly valued because of their strength, hardness, and resistance to moisture. These characteristics make them easy to work with and extremely durable, and that is why they have been used in the manufacture of wooden jewelry, musical instruments, furniture, and handles of many different objects. We present a case of a 44-year-old man who developed pruritus, erythema, and blistering around his right wrist, corresponding exactly to the area where he had worn a wooden bracelet. Thin-layer chromatography performed with the extract of the shavings revealed (R)-4-methoxydalbergione and obtusaquinone (the main components of cocobolo wood) and (S)-4'-hydroxy-4-methoxydalbergione (in lower amounts). Patch-testing with sawdust from the bracelet resulted in a very strong reaction. Patch tests with the pure constituents yielded +++ reactions to the main sensitizers of cocobolo, including obtusaquinone, but also to sensitizers present in other rosewoods. This last fact can be explained by cross-reactivity between different dalbergiones. Contact dermatitis from tropical woods is more frequent than thought, owing to their high sensitizing properties. An exhaustive search can identify the allergen responsible in many cases.