Type:
Educational Exhibit
Keywords:
Oncology, CT, MR, PET-CT, Diagnostic procedure, Neoplasia, Metastases
Authors:
G. Guerrero Martínez1, M. RELAÑO MESA1, S. Comellas1, V. Arroyo Fernández2; 1Badajoz/ES, 2Cádiz/ES
DOI:
10.26044/ecr2019/C-3575
Background
Melanoma is the most serious form of skin malignancy with an incidence that increases with age,
exposure to ultraviolet radiation,
and is influenced by genetic factors.
Melanoma is an aggressive neoplasm that derives from melanocytes.
These cells originate from the neural crest cells that migrate to the skin during early fetal stages,
through central nervous system pathways (fig.
1).
The majority of melanomas grow from preexisting benign nevi.
Melanoma mortality rate depends on the stage of the disease at the time of diagnosis,
and has a five years survival rate of 87% in non-metastatic disease but a 5-15% five years survival rate in advanced visceral metastatic melanoma.
Melanoma's ability to metastasize correlates with malignant cells growth in the deep dermis.
Its stage is important to assess prognosis. In the usual clinical practice,
two staging systems are used to classify melanoma.
Clark levels determine the level of invasion according to the depth of penetration of the dermis,
while the Breslow index determines tumour thickness (fig.
2).
Melanoma first metastasizes by direct extension or to regional lymph nodes,
and then to secondary sites,
via haematogenous spread.
The most common sites are lung,
liver and brain.
However,
melanoma can metastasize to any organ in the more advanced stages of the disease and it may spread in an unpredictable manner. Consequently,
radiological extension study is crucial (table 1).