Perineural spread of tumour has been demonstrated in 24% of an unselected series of 70 patients with squamous carcinomas of the head and neck treated by surgery. Slightly more than half the patients had primary tumours arising within the buccal cavity. Clinical features suggesting perineural infiltration were found in about two thirds of the cases; the symptoms and signs were usually sensory and occurred early in the disease. The mandibular division of the trigeminal nerve was most commonly affected. Perineural spread was more likely to occur with large carcinomas, moderate or poorly differentiated, showing local invasion and lymph node metastases. The associated pathological changes are described and a high incidence of damage to nerve fibres is recorded. The practical implications of perineural spread of tumour are discussed with reference to indications for more radical surgery or for more conservative measures supplemented with other modes of treatment.
Patterns of cartilage invasion by squamous carcinoma were examined in 34 consecutive laryngectomy specimens with particular reference to selective involvement of ossified cartilage. Direct infiltration of the laryngeal framework was demonstrated in 17 cases--16 (out of 17) transglottic carcinomas and in a simgle example of a combined glottic and infraglottic tumour. The susceptibility of ossified laryngeal cartilage to tumour invasion was confirmed, and morphological studies ahve clarified the underlying mechanisms. Invasion is a largely indirect process dominated by local bone destruction by osteoclasts, operating in front of the advancing tumour. One established, carcinoma cells infiltrate and erode bone alone, and the osteoclasts disappear. Reasons for the particular susceptibility of ossified laryngeal cartilage to tumour invasion are discussed and attention is drawn to the role of the tumour-associated osteoclast activating factors such as postaglandins. Therapeutic implications of cartilage invasion are noted.
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