Laboratory Studies
Workup is aimed at establishing the cytologic and histologic diagnosis of the neck mass, establishing the primary carcinoma, evaluating the extent of local (neck) disease, evaluating the extent of systemic spread, and assessing operative fitness (if operation is necessary).
CBC count and differential count provide a baseline hematologic status. Patients with carcinoma of the stomach, carcinoma of the colon, and advanced cancers of the head and neck may present with anemia.
A blood glucose test is useful to screen patients with diabetes mellitus.
Any alteration in the liver enzyme profile can be used to predict either coexisting liver primary disease (eg, cirrhosis, hepatitis) or a liver metastasis. Liver enzyme profiles are also important to determine anesthetic fitness.
BUN and creatinine levels are important to determine anesthetic fitness.
Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are used to assess any possible bleeding diathesis preoperatively.
Electrolyte levels are important, especially in patients with advanced head and neck cancer who have been devoid of oral feeding for a long time.
Determine the patient's blood group.
Perform a urinalysis.
Imaging Studies
Chest radiography can reveal either a primary tumor in a lung or synchronous pulmonary metastasis. Excluding any other coexisting pulmonary pathology is important.
Esophagography (barium swallow) may be helpful in evaluating a hypopharyngeal, postcricoid, and/or esophageal primary tumor.
Ultrasonography is easy and reproducible and is an outpatient procedure. It is an inexpensive investigation, easy to use by a radiologist, and can be used bedside. Most radiologists are well trained in ultrasonography, and only a little more training is required for assessing the neck nodal status. Ultrasonographically guided aspiration cytology can be performed to determine the cause of cervical neck metastasis. It has a specificity nearing 100%. Doppler study can be performed to assess the status of neck vessels.
CT scanning and MRI can be used to reduce the risk of occult disease to 12%. MRI and CT scanning have demonstrated greater sensitivity in the detection of nodes smaller than 1-1.5 cm. CT scanning is the most commonly used investigation to evaluate and stage the disease.
CT scan criteria for assessing nodal metastases include increased size (>1.5 cm for jugulodigastric and submandibular nodes, >1.0 cm for all other cervical nodes, >0.8 cm for retropharyngeal nodes). Unfortunately, lymph node size does not always correlate with metastatic disease.
Other CT scan criteria for assessing nodal metastases are ill defined or irregular bordered mass, rounded shape, central necrosis, and nodal grouping (3 or more nodes in the range of 6-15 mm). The node periphery is usually thick and enhances with contrast. Obliteration of the fat line around the carotid sheath is a sign of sheath infiltration.
CT scanning is more precise than MRI in demonstrating tumor necrosis and extracapsular spread.
MRI tends to reveal retropharyngeal node involvement better than CT scanning does.
Contrast agents (eg, iron oxide) during MRI have demonstrated encouraging results of reduced signal intensity in normal nodes (compared to involved nodes) after contrast administration.
Several studies suggest that 18-F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT scanning is superior to CT scanning alone for neck node involvement. Confirmatory trials to substantiate the accuracy of FDG-PET/CT neck staging are still awaited. Patients who have achieved a complete response at the primary site but have a residual abnormality in the neck may benefit from PET/CT scanning because it is more sensitive and specific than CT scanning alone.
Other Tests
If tumor involvement of the carotid artery is possible, perform 4-vessel cerebral angiography to evaluate the status of the contralateral carotid, intracerebral circulation, and carotid back pressure; also, perform a balloon occlusion test.
Evaluate weight and nutritional status, especially in patients with head and neck cancer.
Perform electrocardiography.
With regard to sentinel node (SN) biopsy, few studies have validated the sentinel node hypothesis for oral and oropharyngeal cancer. The role of SN biopsy in the management of the N0 neck in such patients has yet to be established through prospective trials.
Diagnostic Procedures
Fine-needle aspiration cytology, which is the first and probably most important procedure for further management, can be used to differentiate inflammatory, benign, and malignant pathologies and can provide cytologic distinction (eg, SCCA, adenocarcinoma, germ cell tumor, lymphoma).
Immunocytochemistry can further aid in locating a primary carcinoma.
The primary tumor can be located by palpation, or, in difficult cases, ultrasonographic guidance can be helpful.
Indirect laryngoscopy/fiberoptic nasopharyngolaryngoscopy is used to detect and evaluate a possible primary carcinoma in the head and neck.
Panendoscopy is used to exclude a second primary tumor or to detect the primary tumor if it is not easily detectable. This helps in obtaining a biopsy. The pyriform sinus, base of tongue, nasopharynx, and tonsils are some of the notorious areas of occult tumors, and these areas may require random biopsy if the primary carcinoma site is unknown.
A true-cut or an open biopsy is indicated when needle aspiration cytology findings are inconclusive.
Histologic Findings
Most patients (60-85%) with neck metastases have SCCA; second most common is adenocarcinoma (occurring in 13-22% of patients). Undifferentiated carcinomas and melanomas account for 10% of patients with neck metastases, and 8% of such patients have cervical metastasis. Very rarely, other occult malignant neoplasms, such as sarcomas and germ cell tumors, metastasize to the neck.
Fine-needle aspiration cytology or a biopsy of the neck mass helps in predicting the primary carcinoma site, such as SCCA from upper aerodigestive tract, nasopharyngeal carcinoma, thyroid carcinomas, skin cancer of the head and neck, and breast cancers.
Staging
Cervical metastases of the neck are staged as follows:
-
NX: Regional lymph nodes cannot be assessed.
-
N0: No regional lymph node metastasis is observed.
-
N1: Metastasis is observed in a single ipsilateral lymph node, measuring 3 cm or less in greatest dimension.
-
N2a: Metastasis in a single ipsilateral lymph node is observed and measures more than 3 cm but less than 6 cm in greatest dimension.
-
N2b: Metastasis is found in multiple ipsilateral lymph nodes; none of the nodes measure greater than 6 cm in their greatest dimension.
-
N2c: Metastasis in bilateral or contralateral nodes is observed; no nodes are larger than 6 cm in their greatest dimension.
-
N3: Metastasis is observed in a lymph node that measures greater than 6 cm in its greatest dimension.
-
Anatomy following a Type III modified neck dissection.
-
Levels of neck nodes.
