Probabilities of identifying a micrometastasis in a cervical lymph node from laryngeal cancer. A stereometric approach.

BACKGROUND Lymph node micrometastases are important for prognosis and treatment. Their identification in neck dissection specimens with large numbers of nodes is a matter of chance unless serial sectioning or step sectioning at intervals of 200 μm is used, a method which is impractical. MATERIALS AND METHODS For a case of squamous cell laryngeal carcinoma where a micrometastasis was found in one of the lymph nodes, we performed a stereometric analysis of the probability of identifying the lesion. RESULTS One section at a depth of 100 μm from the surface of each bisected lymph node revealed a micrometastasis, with a range of conditional probability of 75-98%. CONCLUSION Serial sectioning of all excised nodes is unrealistic for routine practice. Knowing the probability of actually identifying a micrometastasis could be important additional information for the clinician and the management of the patient. By performing three sections, the probability of missing a micrometastasis within a normally appearing node would be 2-25%.