| Nodular melanoma |
Nodular melanoma (NM) is the most aggressive form of melanoma.[1] It tends to grow more rapidly in thickness (vertically penetrate the skin) than in diameter compared to other melanoma subtypes.[2] Instead of arising from a pre-existing mole, it may appear in a spot where a lesion did not previously exist. Since NM tends to grow in depth more quickly than it does in width, and can occur in a place that did not have a previous lesion, the prognosis is often worse because it takes longer for a person to be aware of the changes. NM is most often darkly pigmented; however, some NM lesions can be light brown, multicolored or even colorless (non-pigmented). A light-colored or non-pigmented NM lesion may escape detection because the appearance is not alarming, however an ulcerated and/or bleeding lesion is common.[3] Polypoid melanoma is a virulent variant of nodular melanoma.[3]
The microscopic hallmarks are:
Therapies for metastatic melanoma include the biologic immunotherapy agents ipilimumab, pembrolizumab, and nivolumab; BRAF inhibitors, such as vemurafenib and dabrafenib; and a MEK inhibitor trametinib.[4]
Important prognosis factors for nodular melanoma include: