Further investigation to determine precisely the extent of the disease is important in terms of prognosis, treatment, entry into clinical trials, research and audit.

Following pathological microstaging of a patient’s melanoma (see section 3.7) the presence of metastatic spread can be determined using three techniques:

• Surgical: assessment of the impalpable node by sentinel node biopsy and of the palpable node (see section 4)
• Imaging: conventional radiography, ultrasound scanning (US), computerised tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET)
• Blood Tests: routine haematology, tumour markers, liver function tests and lactic dehydrogenase (LDH).

5.1 Imaging techniques

5.1.1 CHEST X-RAY

One large retrospective study was identified that examined the role of chest X-ray (CXR) in staging melanoma in 876 asymptomatic patients with stage I or II melanoma.¹⁵¹ One hundred and thirty patients (15%) had suspicious CXR findings necessitating further investigation but only one patient (0.1%) was found to have a true pulmonary metastasis. Evidence level 3

5.1.2 ULTRASOUND SCANNING

Two retrospective studies have examined the ability of lymph node ultrasound scanning (US) to stage melanoma. One study of 87 patients found the sensitivity of US to be 86% and the specificity 74%.¹⁵² Ultrasound examination of the regional lymph nodes is a less accurate means of determining nodal status than sentinel node biopsy.¹⁵³ Evidence level 3

5.1.3 COMPUTED TOMOGRAPHY

Two relatively small retrospective studies have shown that computerised tomography (CT) scanning does not assist in staging and may be counterproductive by generating false positives.^{154, 155} Evidence level 3

Chest X-ray, ultrasound scanning and computerised tomography scanning are not indicated in the initial assessment of primary melanoma unless indicated for investigation of clinical symptoms and signs.

5.1.4 MAGNETIC RESONANCE IMAGING

Magnetic Resonance Imaging (MRI) is unable to image the lungs in sufficient detail to exclude parenchymal disease such as metastases, and is therefore unable to provide a comprehensive assessment of disease status in melanoma patients. No studies were found that examined the routine use of MRI to identify distant disease in stage I-III melanoma. There is insufficient evidence to make a recommendation on the role of MRI scanning and melanoma staging.

5.2 Laboratory investigations

Investigations such as full blood counts (FBC) and liver function tests (LFT) are not helpful in identifying asymptomatic patients with distant disease.^{156, 157} Elevated lactate dehydrogenase (LDH) in the absence of clinical symptoms or signs is the first indicator of stage IV disease in 12.5% of patients. By the time other blood parameters are significantly deranged, the patient will have other manifestations of metastasis.^{156, 157} For patients with advanced disease, LDH is now included in the AJCC classification system.¹¹⁰ The evidence and availability of tumour markers such as S100 protein, Melanoma Inhibitory Activity (MIA) protein and tyrosinase mRNA are limited. Investigating these markers is not routinely indicated.²⁰² Evidence level 3

Routine blood tests are not indicated in staging asymptomatic melanoma patients.