Radical neck dissections for squamous carcinomas: pathological findings and their clinical implications with particular reference to transcapsular spread.

Two hundred fifty radical neck dissections, undertaken for mucosal squamous carcinomas of the head and neck, were reviewed with reference to pathological findings and their clinical implications. No major differences in descriptive surgical pathology were established between irradiated and non-irradiated resections. In general, irradiated dissections had lower total node counts and somewhat fewer nodal metastases involving a smaller number of different nodal groups. The topography of nodal deposits was similar in irradiated and non-irradiated resections. Palpable keratin granulomas (without intact tumor) were almost confined to irradiated patients. Transcapsular spread of tumor from involved lymph nodes was common: it was demonstrated in 160/188 'positive' dissections (85%) and was subclassified as 'macroscopic' in 90 and 'microscopic' in 70. The incidence and extent of transcapsular spread was similar in irradiated and nonirradiated resections. It was more frequently observed in association with large nodal masses but it was also regularly found with small nodal deposits less than 3 cm in diameter. Statistical analyses showed strong associations (p less than 0.0005) between the presence and/or extent of transcapsular spread and subsequent recurrence in the operated neck and overall survival. The predictive value of other clinical and pathological features vis-a-vis local neck recurrence such as numbers of involved nodal groups was weaker. Macroscopic transcapsulr spread emerges as the major prognostic factor for recurrent disease in the neck (p less than 0.0001). Attention is drawn to the advantages of accurate descriptive categories ('macroscopic', 'microscopic') for this critical prognostic feature.