Human keratinocyte immortality is genetically recessive to the normal phenotype of limited replicative lifespan and appears to require the dysfunction of p53 and the cyclin D-Cdk inhibitor p16. In order to test for the inactivation of other candidate replicative lifespan genes in the immortal cells of human tumors, we developed a series of mortal and immortal keratinocyte cultures derived from neoplastic lesions of the head and neck which were amenable to molecular genetic analysis by the loss of heterozygosity (LOH) technique. The results indicate that keratinocyte immortalization in head and neck squamous cell carcinoma (SCC-HN) development involves the inactivation of at least two further pathways to senescence and four in all. Chromosomes 1, 4 and 7 carry genes representing immortality complementation groups C, B and D respectively and immortal keratinocytes showed LOH at either 4q32-q34 between D4S1554 and D4S171 (group B) or 7q31 (group D) but never 1q25 (group C). These results tentatively suggest that the genes responsible for the immortality complementation groups encode proteins on the same pathway to senescence. In addition, all of the immortal keratinocyte lines possessed high levels of telomerase activity and a suppressor of telomerase activity has been mapped to the short arm of chromosome 3p. Five out of eight lines showed LOH at 3p21.2-p21.3, a region which may carry a gene capable of suppressing SCC-HN telomerase. However, alternative mechanisms of telomerase reactivation were also suggested by our results. None of the above genetic alterations were seen in seven senescent neoplastic keratinocyte cultures. Other loci harbouring antiproliferative genes implicated in replicative lifespan showed few or no alterations and any alterations seen were additional to those described above.

Acute infective inflammation of the epiglottis and supraglottic tissues in the adult is an uncommon but life-threatening condition. 1•4 The incidence of adult cases may even be on the increase. 5 However, epiglottitis in association with infection of a pre-existing epiglottic cyst is unusual. CASE REPORT In January 1988 a 62-year-old man presented with several hours history of sore throat, dysphagia and pyrexia. A cyst on the left side of his epiglottis had previously been noted in May 1985 during the course of an anaesthetic laryngoscopy. The epiglottic cyst had been asymptomatic and had required no treatment at that time. On admission to hospital his axillary temperature was 37.5°C. There was a cellulitis of the skin overlying the anterior aspect of his neck and sternum. The patient had a muffled voice and was unable to swallow his saliva. However, he had no stridor in the sitting position at rest and had no palpable lymph nodes. Humidified oxygen therapy was administered to the patient in the sitting position. Throat swabs, blood cultures, a full blood count and a lateral soft tissue X-ray of neck were obtained. The lateral X-ray of neck demonstrated the extended cervical spine typical of upper airways obstruction, widening of the prevertebral soft tissue •F.F.A.R.C.S .. Senior Registrar in Anaesthesia.