Neck metastasis with unknown primary

· The patient presents with diagnosed neck metastasis and no primary can be identified.

· The most common sites are nasopharnx, base of tongue, hypopharynx, tonsillar fossa

· These areas must be thoroughly evaluated in to identify the occult primary

· In 80% of cases the primary will be identified during evaluation.

Most surgeons advocate a modified radical neck dissection for any patient with neck disease.

· If no primary can be identified post-operative XRT can be given after MRND to include the areas at highest risk: tonsillar fossa, hypopharynx, nasopharynx, base of tongue.

The prognosis is not significantly different from neck metastasis where a primary can be identified (50% 5 year survival).

Head and neck

What are the causes of a neck mass

• congenital

• branchial cyst

• thyroglossal cyst

• cystic hygroma

• dermoid

• laryngocoele (diverticulum through thyrohyoid membrane, congenital)

• thymic cyst

• lymph node

• hot (eg bacterial) and cold abscess (eg TB)

• reactive lymph node

• lymphoma

• generalised infection (EBV)

• chronic infection (cat scratch, MAIS)

• secondary malignancy (H/N, thyroid, oropharynx, lung, breast, oesophagus, upper GI, melanoma)

• sarcoidosis

• superficial structures

• lipoma

• dermoid cyst

• sebaceous cyst

• lateral aberrant thyroid

• thyroid

• pharyngeal pouch (Zenker's)

• salivary glands

• parotid tumour

• submandibular tumour

• enlarged submandibular gland

• plunging ranula

• vascular

• carotid body tumour (chemodectoma)

• false aneurysm

• haemangioma

• glomus tumour

• innominate artery aneurysm

• innominate artery tortuosity

• neural

• ganglioneuroma

• neurofibroma

• musculoskeletal

• transverse process C2

• cervical rib

• sternocleidomastoid tumour

What is the approach to a neck mass in an adult? (also see below)

• consider age of patients

            • children usually inflammatory or congenital

            • adults >40 years usually neoplastic

• consider position in neck

• Thorough head and neck examination

• USS (solid vs. cystic, lymph node vs. salivary gland)

• CT/MRI

• FNA

• EUA, endoscopy and guided-biopsies

• open biopsy only if FNA negative, no evidence of primary and can proceed

directly to neck dissection if frozen section reveals SCC, melanoma or adenoca

(except for supraclavicular adenoca) (or via an appropriate incision for later neck

dissection)

• open biopsy in children is often appropriate

Why is an open biopsy of a cervical lymph node contraindicated

• previous open biopsy increases the rate of regional and distant recurrence (up to

50-100% relative increase in recurrence)

Evaluation of a potentially malignant neck mass

Complete history and physical examination is required

· Complete examination in office including:

· skin & scalp, ears (pneumatic otoscopy), mouth (lip, buccal mucosa, tongue including bimanual palpation), oropharynx

· Flexible nasendoscopic examination of nasopharynx, hypopharynx and larynx. · Systematic cranial nerve examination.

· The neck is examined systematically

· Chest and abdomen are examined

Investigations

· FNA of the neck mass

            It should be performed (95% accurate) usually in office on first consultation.

            If initial FNA is non-diagnostic consider repeating the FNA possibly under the      guidance of a cytologist and or with US-guidance

· CT of head, neck and thorax

· PET scanning:

            FDG PET is more sensitive than CT, esp. detecting lung mets than CXR or CT

            will detect unknown primary in 50% of cases

            It upstages about 15% of patients when used in diagnostic work-up

            In about 10% of cases a synchronous primary is detected

            Patients with more glucose avid tumours have worse prognosis and less response to XRT.

Management

· For SCC on FNA

· Triple endoscopy (flexible nasoendoscope, panendoscope, and bronchoscope) consists of examination of esophagus, mouth, pharynx, larynx and tracheobronchial tree.

· If no lesion is seen, a blind biopsy is performed of tonsillar fossa, piriform sinus (hypopharynx), nasopharynx and base of tongue.

· A modified radical neck dissection is performed on the ipsilateral side with post-op RT to treat neck and likely occult primary sites

· Primary radiation alone can be used without surgery for persistent or recurrent disease

· For lymphocytes on FNA

It is possible that the lesion could be inflammatory, lymphoma or even Warthin’s tumour (salivary papillary cystoadenoma).

Further evaluation using imaging

Excision biopsy is reasonable if a diagnosis has not been achieved by FNA once an SCC has been excluded.

· For Adenocarcinoma on FNA

Further evaluation for primary sites in thyroid, salivary glands and infracalvicular disease is required.