It is important to recognize that the squamous papilloma of the mouth behaves differently from those of the nasal, paranasal and laryngeal regions. While the others are clinically and microscopically identical to their oral counterparts, they have a much higher recurrence rate, are almost always multiple and will often proliferate continuously over time. Laryngeal papillomas may, in fact, be so relentlessly proliferative that they cause life-threatening asphyxiation, and some worry about malignant transformation in long-standing cases.