REVIEW Ultrasound of malignant cervical lymph nodes
A.T. Ahujaa, M. Yingb, S.Y. Hoa, G. Antonioa, Y.P. Leea, A.D. Kinga and K.T. Wonga Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China; and bDepartment of HealthTechnology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China Corresponding address: Dr Anil T. Ahuja, Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories Hong Kong SAR, China. Email: email@example.com Date accepted for publication 21 January 2008 Abstract Malignantlymph nodes in the neck include metastases and lymphoma. Cervical nodal metastases are common in patients with head and neck cancers, and their assessment is important as it affects treatment planning and prognosis. Neck nodes are also a common site of lymphomatous involvement and an accurate diagnosis is essential as its treatment differs from other causes of neck lymphadenopathy. On ultrasound,grey scale sonography helps to evaluate nodal morphology, whilst power Doppler sonography is used to assess the vascular pattern. Grey scale sonographic features that help to identify metastatic and lymphomatous lymph nodes include size, shape and internal architecture (loss of hilar architecture, presence of intranodal necrosis and calcification). Soft tissue oedema and nodal matting areadditional grey scale features seen in tuberculous nodes or in nodes that have been previously irradiated. Power Doppler sonography evaluates the vascular pattern of nodes and helps to identify the malignant nodes. In addition, serial monitoring of nodal size and vascularity are useful features in the assessment of treatment response.
Keywords: Cervical lymph nodes; metastases; lymphoma; ultrasound.
Assessment of nodal status is essential in patients with head and neck carcinomas as it predicts prognosis and helps in the selection of treatment options[1,2]. In patients with proven head and neck carcinomas, the presence of a unilateral metastatic node reduces the 5-year survival rate by 50%, whereas the presence of bilateral metastatic nodes reduces the 5-year survival rate to25%. Metastatic cervical lymph nodes from head and neck carcinomas are usually site specific with respect to the location of the primary tumour. Therefore, assessment of the distribution of metastatic nodes in patients with unknown primary may provide a clue to the site of the primary tumour. Moreover, metastatic nodes in an unexpected site indicates that the primary tumour is biologically moreaggressive. Besides metastases, lymphoma is also a common malignant disease and head and neck involvement is relatively
common. Clinically, lymphomatous cervical lymph nodes are difficult to differentiate from other causes of lymphadenopathy including metastatic nodes. As the treatment options differ, accurate identification of the nature of the diseases is essential. The role ofultrasound in the assessment of cervical lymphadenopathy is well established. It is particularly sensitive compared to clinical examination (96.8% and 73.3% respectively) in patients with previous head and neck cancer with post-radiation neck fibrosis. When combined with guided fine needle aspiration cytology (FNAC), the specificity of ultrasound is as high as 93%. Although computed tomography (CT)and magnetic resonance imaging (MRI) are also used to evaluate cervical lymph nodes, the nature and internal architecture of small lymph nodes (55 mm) may not be readily assessed. In addition, MRI may not identify intranodal calcification which is a useful feature in predicting metastatic nodes from papillary carcinoma of
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