A primary lesion is the most common manifestation of malignant melanoma of the head and neck region. This lesion can vary in appearance from the classical black-pigmented, raised lesion to an enlarging, skin-colored (amelanotic) mole (Fig. 1A and B). Melanoma can arise from a preexisting nevus or normal skin. The appearance of melanoma may be
similar to other generally noninvasive skin cancers such as basal cell and squamous cell carcinoma, requiring biopsy for pathologic identification.
Primary cutaneous melanoma is identified in several ways. Classically, worrisome skin lesions that may be melanoma are described with the ABCDE mnemonic: Asymmetry, irregular Borders, variable Color, Diameter >6 mm, and Evolving lesions. Melanoma has two different growth phases: radial growth spreads laterally and superficially, whereas vertical growth penetrates deeply and has higher metastatic potential. Historically, melanoma is also identified by distinct histological subtypes.
Superficial spreading melanoma (SSM), the most common histological subtype, accounts for 70% of all primary melanomas and is most commonly seen in the head, neck, torso, and lower extremities. Frequently arising from an existing nevus, SSM is usually flat to slightly raised, with variable pigmentation and irregular borders (Fig. 1A). Growth of these tumors can be indolent initially; the radial growth phase may last for many years before signs of rapid vertical growth appear. Peak incidence of SSM occurs at a median age of 56 years (3).
The second most common histological subtype is nodular melanoma (NM). This subtype commonly occurs in the head, neck, and torso. It is characterized by a raised, frequently symmetric, darkly pigmented lesion with rapid onset and growth. Most of these lesions are pigmented, but a small percentage may be amelanotic (Fig. 1B). NM has no radial growth phase and a rapid vertical growth phase, resulting in a thicker lesion with higher risk of metastatic spread. The median age of onset is 49 years (3).
Accounting for about 10% of all melanomas, lentigo maligna melanoma (LMM) commonly occurs in the head and neck region like SSM, but arises from a preexisting lentigo maligna lesion that usually has been present for more than five years prior to diagnosis. LMM is frequently a large (>3 cm), flat lesion with brown to black pigmentation; it has an indolent course with a prolonged radial growth phase (Fig. 1C). LMM occurs in older individuals, with a median age of onset of 70 years (3).
Mucosal lentiginous melanoma (MLM) includes lesions occurring on the mucosa of the naso-oropharynx, conjunctiva (ocular melanoma), genitals, or anus. MLM is clinically aggressive and appears as a flat or ulcerated, pigmented, irregular lesion. It can frequently be missed on physical exam and then diagnosed retrospectively after the appearance of nodal metastases. Median age of onset is 56 years (3,4).
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Complete Guide to Preventing Skin Cancer. We all know enough to fear the name, just as we do the words tumor and malignant. But apart from that, most of us know very little at all about cancer, especially skin cancer in itself. If I were to ask you to tell me about skin cancer right now, what would you say? Apart from the fact that its a cancer on the skin, that is.