NECK MASSES DR THOMAS LOH, MBBS, FRCS

Transcription

1 NECK MASSES DR THOMAS LOH, MBBS, FRCS Head & Neck Surgeon Head & Neck Surgical Oncology Department Of Otolaryngology Head & Neck Surgery, National University Hospital Department Of Otolaryngology, National University Of Singapore 1

2 INTRODUCTION Neck masses are a common problem in the practice of Otolaryngology. There are many ways in which neck masses can be classified but the two most common methods are by classifying them according to site and etiology. Neck masses may be benign or malignant. The most common neck masses are enlarged lymph nodes and thyroid nodules. This chapter will aim to provide you with 1. A rational approach to classifying neck masses in a clinically useful manner 2. A description of the common differential diagnosis of neck masses seen locally 3. An understanding of the investigations involved in the diagnosis of neck masses 2

3 Differential Diagnosis Of Neck Lumps (Fig. 1) Neck Masses Anterior Triangle Midline Posterior Triangle Lymph node Submandibular mass (calculi) (sialdenitis) Branchial cyst Submental lymph node Thyroglossal cyst Dermoid cyst Lymph Node Neuroma, Schwannoma Carotid body tumor Thyroid nodule Neuroma, Schwannoma Thyroid nodule Figure 1. Diagram for differential diagnosis of neck 3

4 It is useful to divide the neck systematically into a few regions so that corresponding neck masses that do arise from these regions can be classified easily. Clinically, the neck can be divided into anterior and posterior triangles (including the supraclavicular fossa). This is because the outline of the sternocleidomastoid muscle (SCM) is always well outlined. In addition, midline masses are also common in clinical practice and it is therefore useful to include midline masses as a separate grouping. The above list is NOT exhaustive but it does give the clinician a working approach to solving the problem of a neck mass. Common anterior triangle neck lumps 1. Lymph node (see below) 2. Submandibular mass A submandibular mass may arise from the submandibular gland itself or enlargement of the submandibular nodes. Infection in or metastasis from a primary tumour of the oral cavity may lead to reactive submandibular lymphadenopathy. It may also be due to calculi (Figure 2) in the submandibular duct causing sialadenitis, which presents as painful fluctuating enlargement of the submandibular gland associated with eating. Fig. 2 Submandibular calculus (left) causing sialadenitis. 4

5 3. Branchial cyst This occurs in young adults and the history is of a slowly enlarging painless neck mass. Very often, on examination, part of the cyst lies deep to the sternocleidomastoid muscle and extends anteriorly. It is firm and trans-illumination is NOT a feature. CT scan shows a well defined cyst in the upper part of the neck, just below the submandibular gland. The treatment is surgical excision. 4. Carotid body tumor This is a pulsatile mass located at the bifurcation of the carotid artery corresponding to level II of the neck. The lesion is slow growing and may present with a bruit. When this lesion is suspected, a CT scan or MRI should be performed as the initial evaluation rather than fine needle aspiration cytology (FNAC). 5. Neural masses (Schwannoma, Neuroma) These tumours arise from peripheral neural structures of the neck. These include the branches of the cervical plexus, the brachial plexus, vagus, phrenic and cervical sympathetic trunk. The clue to these neural masses is that it is mobile in 1 plane of movement, i.e. perpendicular to the long axis of the nerve. These are slow growing and usually benign. 6. Thyroid nodule (See notes on thyroid nodules) Common mid-line neck lumps 1. Lymph node. In the mid-line, this is usually located at the submentum. (Figure 3) Fig.3. Submental lymph node due to tuberculosis. 2. Thyroglossal cyst. (Fig. 4) 5

6 This usually occurs in the young adults although it may occasionally occur in the older age groups. It may move with protrusion of the tongue but this is not always obvious. The treatment is to excise the cyst as it may increase in size with time, or it may get infected and present as an abscess. Fig. 4. Thyroglossal cyst. 3. Dermoid cyst. These are epithelial lined cyst derived from ectodermal elements during the formation of the embryo. They are believed to be cleaved off epithelial cell rests pinched off from planes of cleavage during the multiple foldings of the embryonic formation. 6

7 4. Thyroid nodule. (Figure 5) Fig5 Thyroid nodule. Common posterior triangle neck lump 1. Lymph node. (see below) This may be benign or malignant. It is by far the most common cause of posterior triangle neck lump. 2. Neural masses Schwannoma Neuroma This may be due to neuromas of the supraclavicular nerves, the cervical plexus, brachial plexus or accessory nerve. 7

8 Common Causes Of Enlarged Lymph Nodes (Fig. 6) Lymph Nodes Infectious Neoplastic Inflammatory Viral Bacterial Parasitic Lymphoma Metastasis Kikuchi s Kimura SLE Sarcoidosis EBV, HIV, others Streptococcus, Staphylococcus, Klebsiella, etc Toxoplasma Head and Neck Primary Other primary sites Tuberculosis NPC, oral cavity, oropharynx larynx hypopharynx thyroid skin Lungs Breast GIT tract Renal 8

9 1. Infectious Viral, eg. EBV(infectious mononucleiosis), HIV, etc Bacterial Tuberculosis Parasitic, eg toxoplasma 2. Neoplastic a. Lymphoma b. Metastasis from primary in the head and neck i) NPC, squamous cell carcinoma of oral cavity (Fig. 7), tonsils, pharynx, larynx, thyroid. ii) Metastasis from primary outside head and neck region, eg. Lungs, gastrointestinal tract, breast, etc. Fig. 7 Left cervical nodal metastasis from a soft palate squamous cell carcinoma. 9

10 3. Inflammatory A common inflammatory cause of cervical lymphadenopathy includes Kikuchi s lymphadenitis. This is a pathological diagnosis of necrotizing lymphadenitis seen commonly in young females, presenting as painful cervical lymphadenopathy which could be recurrent. The diagnosis is made on excision biopsy and histological examination of the excised node. There is no specific treatment needed. These patients often undergo episodes of flaring up of the nodes which eventually resolves spontaneously. The significance of this condition is to differentiate from lymphoma resulting in cervical lymph node enlargement. Other causes include systemic lupus erythromatosus (SLE) and sarcoidosis which is rare in Singapore. Evaluation Of Neck Masses In any patient who presents with a neck mass, the key in the evaluation process is a thorough history and complete examination of the head and neck. In particular, examination of the nasopharynx is extremely important in our population. Indeed, just from a good clinical history and examination, we will be able to have a working diagnosis in the vast majority of the patients. Investigations should be directed at the suspected diagnosis. Investigations indicated in the evaluation of the neck lump: 1. Imaging (CT scans, MRI, Ultrasound) Scans are usually performed because the diagnosis is cancer and we need to stage the disease. The scans are also useful in assisting us to fully appreciate the nature of the lesion (eg vascular lesions, abscess, lymph node, etc). It will be useful as a guide when surgery needs to be performed as it will give the surgeon an appreciation of the extent, the depth, the surrounding structures, etc. Ultrasound is an effective way to assess the thyroid gland. It may also be utilized to image the neck although it does not show up as well as CT or MRI in the definition of soft tissues. 10

11 2. Fine needle aspirate cytology (FNAC) This is usually performed when the mass is suspicious of a malignancy or where it is large and does not regress despite antibiotics. It is a key investigative tool in patients presenting with a neck mass. 3. EBV serology This test may be utilized to provide a direction in our investigation of a patient with suspicious cervical lymphadenopathy. However, it is NOT the standard of diagnosis in NPC. A normal serology does not necessarily imply the absence of NPC and conversely an abnormal EBV is not always confirmatory of NPC. Important points 1. A thorough history and examination of the head and neck is mandatory for all patients with a neck mass. 2. Malignant lymph nodes in the neck are usually due to NPC or squamous cell carcinoma of the head and neck. 11