Pathology of Neck Dissections

Abstract

The presence of cervical lymph node metastasis at the time of presentation and treatment is the main adverse prognostic factor for patients with squamous cell carcinoma of the upper aerodigestive tract: its presence reduces the 5-year survival by approximately 50%, irrespective of the primary site. However, clinical and pathologic findings specific to lymph node metastasis provide additional prognostic information related to tumor recurrence and overall survival. The basic histopathologic features of cervical lymph node metastasis of prognostic significance are: extracapsular spread (ECS) ; the level , number, and size of positive lymph nodes; pattern of lymph node response; and soft tissue deposits. 2-6 Furthermore, accurate pathologic staging of the neck of patients with head and neck cancer is important for providing information and optimizing the treatment plan. Gross examination of specimens Because the main anatomic and radiologic landmarks are lacking in neck dissection specimens, the orientation and labeling of the lymph node levels must be performed by the surgeon. Ideally, each level and sublevel of lymph nodes should be labeled and submitted to the pathology laboratory in separate containers, one container for each level or sublevel of lymph nodes removed. The pathologist has a choice of two methods for examination of the specimens 6,8. The traditional method of assessing dissected nodes relies on the identification of lymph nodes by dissection of the received specimen. All lymph nodes visible or palpable in each specimen are carefully dissected from connective tissue with a rim of perinodal connective tissue or fat. The number of lymph nodes should be noted; if tumor is present, the size in centimeters of the metastases and presence of ECS are also noted and recorded. Nodes greater than 2 to 3 cm are bisected along their longest axis plane, and both halves are submitted. Smaller nodes are submitted in toto. If a group of matted lymph nodes is present, two to three sections through the nodes often are adequate to document the extent of tumor In 2003, Jose et al 6 designed a new method for pathologic examination of neck dissections. In this method; the node levels and sublevels are sent to the laboratory in separately labeled containers and fixed in formalin. Each specimen is cut into 2mmthick blocks, embedded in paraffin and sectioned at 6 microns thickness and stained with hematoxylin and eosin. Any macroscopically enlarged lymph nodes present are noted and embedded in their entirety. Care must be taken to count only once those lymph nodes that appear in multiple sections . With this method, the lymph node yield obtained is 50.4 nodes per neck dissection and the average number of microscopic slides generated is 63 (Level l-IV dissection). This technique allows accurate and comprehensive pathologic staging of cervical metastases, because the entire neck dissection specimen is examined rather than only apparent lymph nodes. 6