A descriptive term for ribbon-like strands of dermal papillae and epithelial cells that extend vertically from the basal cell layer to the epidermal canopy, and which periodically tether the fluid-filled bullae to the dermis
and have been fancifully likened to festoons or party streamers.
Aetiology Festooning occurs in the subepidermal nonacantholytic unilocular blisters of bullous pemphigoid, and has been described in dermatitis herpetiformis, porphyria cutanea tarda, and cutaneous toxicity linked to propionic acid derivatives (NSAIDs).
Reference J Cutan Med Surg. 1999 Jan;3(3):162-6