MIS is defined as Stage 0, confined to the epidermis and adnexal epithelium. It was classified as a subset of the International Society for the Study of Vulvovaginal Disease classification of'VIN (31) but has subsequently been discarded in the newer classification (31a). The concept of MIS was first described in 1949. In 1992, a panel at the Consensus Development Conference sponsored by the National Institutes of Health officially acknowledged this diagnostic category (32). The terminology was inspired by that of cutaneous squamous cell carcinoma; however, there is one major difference. Squamous cell carcinoma in situ is a premalignant condition, whereas MIS is considered a malignancy with a risk of metastasis, where there is an inability to detect an invasive component with tissue processing with standard histopathological techniques.
MIS often presents as a macular deeply pigmented lesion, initially uniform in appearance, but with time develops asymmetry, irregular borders, and color variegation (Table 5).
MIS is characterized histologically by a proliferation of malignant melanocytes confluently in the epidermis (Fig. 17). In the mucosal lentiginous type, the melanoma cells are arrayed predominantly in single cells in association with elongation of rete ridges. Pagetoid intraepidermal spread of melanoma cells is usually minimal to
absent. In contrast, MIS of the superficial spreading type has prominent pagetoid scatter of melanoma cells in the epidermis.
Excision with 0.5 to 1 cm margins is recommended for treatment. Positive margins require additional excision until clear histopathological margins are obtained. Additionally, referral to a melanoma specialist is indicated to examine the entire skin surface, which is at increased risk of additional primary melanomas, and complete melanoma education and prevention (33).
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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.