To the Editor.—
Caterpillar dermatitis has been recognized since Roman times. Several types of caterpillar spines can irritate the skin by direct contact. Hypodermal glands supply the hollow spines with poison.1,2 Cocoon dermatitis is less well recognized.2 The caterpillar breaks off the poisonous spines and incorporates them into the cocoon as protection during pupation. I report the case of a patient who unknowingly encountered such a cocoon.
Report of a Case.—
An 18-year-old man was seen at University Health Service, Madison, Wis, with an inflamed, swollen left middle finger of 3 days duration. It had started as an itchy stinging sensation following yardwork. He had worn his father's work gloves while mowing the lawn. He denied contact with chemicals.Physical examination revealed a healthy young man with an acutely swollen, tender, erythematous left middle finger. Tiny vesicles were noted on the dorsoradial aspect. Treatment was initiated with dicloxicillin
Shenefelt PD. Moth Cocoon Dermatitis. Arch Dermatol. 1991;127(3):424-425. doi:10.1001/archderm.1991.01680030150028