Benign vulvar melanosis (melanotic macule or genital lentigo) consists of a brown discoloration and is generally asymptomatic (Fig. 2). Table 2 outlines the symptoms, clinical appearance, differential diagnosis, and therapy of melanosis. It can be found in a variety of vulvar locations including the periurethral area (22). Often, there will be more than one lesion present. Melanosis may be found incidentally during a pelvic examination. Melanosis of the vulva may mimic melanoma on visual appearance with intensely pigmented irregular macules (Fig. 3) (23-25).
The size of the various forms of melanosis varies, but it tends to be several millimeters (general range of 1-15 mm in diameter) (26). The margins vary from smooth to jagged. There is an even distribution of brown to black pigmentation. This condition is not associated with systemic diseases or induced by sunlight exposure. It may occur in episiotomy sites. At times, lentigines may be an expression of a genetic disorder such as Peutz-Jeghers syndrome or LEOPARD syndrome. Also, they have been reported in association with lichen sclerosus (27). The patient in Figures 4 and 5 has extensive lentigos, and, in addition, a biopsy from her superior right vulvar aspect revealed thick hyperkeratosis with changes in the papillary dermis of lichen sclerosus.
If small, and the area is concerning, an excisional biopsy is recommended to completely remove the area of concern for diagnostic confirmation. If the darkened area is large, an incisional biopsy may be performed.
Table 2 Melanosis
Melanosis Asymptomatic Pigmentation;
Melanoma Atypical junctional melanocytic hyperplasia Vulvar intra-
Generally, no therapy irregular tan to brown/black patches required once diagnosis is established
Margins can be jagged or smooth epithelial neoplasia
On visual inspection of the vulva, it can be difficult to differentiate melanosis from melanoma; however, it is not difficult on histologic grounds. Melanosis lacks a substantial melanocytic proliferation, nesting pattern of melanocytes, or melanocyte atypia. Dendritic melanocytes are normal in number or only slightly increased along the basal layer of the epidermis in association with hyperpigmentation (Fig. 6). On occasion, the melanin pigment is also located in the upper dermis. Acanthosis may be present (28).
Melanosis is a benign process, and thus no treatment is needed once the diagnosis is made (24). However, it is important to visualize the entire vulva when examining these patients and consider biopsy if any areas are concerning. Figure 7 demonstrates VIN 3 with a darkened, gray-brown appearance. At times, VIN may be associated with melanosis (Fig. 8).
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