Your differential diagnosis should include all of the entities listed, because they can all present as a pigmented lesion. The most common location is the head and neck area which accounts for nearly one third of the cases. Hemangiomas are primarily tumors of childhood, but cases have been observed in adults. However, it may arise at any location where melanocytes are present, including the oral cavity.
Malignant melanoma is the third most common form of skin cancer and is usually observed in adults.
Most oral malignant melanomas are found on the hard palate and maxillary gingiva or alveolar mucosa. It typically begins as a brown to black area of pigmentation that exhibits irregular borders. An average adult will exhibit 10-30 nevi on the skin. Intraoral nevi do occur but are not as common as those that occur on the cutaneous surface. Most cases of intraoral pigmented nevi appear on the palate or gingiva, although any intraoral site may be involved.