[Special aspects of histopathologic diagnosis in laser microsurgery of cancers of the upper aerodigestive tract]

Abstract

Histological examination of CO2 laser-resected specimens reveals a thin layer of carbonisation, beneath which the cellular architecture is preserved, permitting adequate assessment. With early staged laryngeal, oral and pharyngeal carcinomas, it is usually possible to remove the tumour as a single block, and the margins can be studied by parallel histologic sections. Advanced tumours, regardless of their localisation, demand resection in several blocks. Each tissue block is carefully orientated and the deep surface of every specimen is stained. Accurate mapping of every block is essential to enable the surgeon to identify the precise location of each specimen in the patient. The specimens are vertically sectioned after paraffin wax embedding. Grading, depth of invasion, lateral and basal margins are examined. Like in conventional surgery, it is technically impossible to examine all margins of a large specimen. With vertical sections only limited information can be obtained about lateral and basal margins. If deep tumour infiltration reaches cartilage or bony structures, clear microscopic margins are difficult to prove after laser resection. Finally it must be possible for the surgeon to recreate a complete, 3-dimensional mosaic of the entire lesion to achieve accurate pT-staging.