Sprouting epidermoid cysts.

Five unusually shaped (i.e. 'sprouting') epidermoid cysts in the upper lip, elbow and foot are reported. The tumours seldom produced symptoms. The maximum diameter was 25-48 mm. The complete removal including a sprouting bud is necessary. Histologically, partial to complete cyst wall rupture was recognised. A pulsion diverticulum due to variations in the thickness and strength of the cyst wall, a foreign body reaction against inner keratinous mass without obvious bacterial infection, and/or outer fibrous band(s) acting as constriction band(s), are proposed as possible causes of the 'sprouting'.