BENIGN LARYNGEAL TUMOURS VOCAL CORD POLYPUS 177 Although this is probably the most common laryngeal mass its aetiology is not understood. The polyp may arise from an area of unresolved infection or it may be a response to traumatic abrasion or haematoma formation. It occurs almost exclusively on a vocal cord and arises from the subepithelial connective Fig. 80. Laryngocele. Radiograph showing a typical air-filled ca\ity. Fig. 81. Laryngeal polypus. Microphotograph of polypus showing below left vocal cord. tissue of Reinke's layer (Fig. 81). A single vocal cord polyp must be differenti- ated from the polypoidal swelling of the vocal cords which is part of the chronic laryngitis spectrum (p. 161). A single polyp is removed at direct laryngoscopy and seldom recurs.