Table 1.

Comparison of benign lesions and malignant oral mucosal melanoma.

	Macule	Nevi	Melanoacanthoma	OMM
Prevalence in melanocytic lesions	62% (48, 49)	15% (48, 49)	0.8% (48, 49)	0.7% (48, 49)
Color	Gray to brown to black	Brown, bluish-gray or black, 15% non-pigmented	Brown or black	Variable
Size (mean diameter)	<1 cm	0.5cm	Several centimeters	4 cm
Shape	Flat, solitary & well-circumscribed	Well-demarcated but elevated	Flat or slightly raised	Asymmetric with irregular outline
Commonly occurred site	Lip & gingiva	Palate	Buccal mucosa	Hard palate & maxillary gingiva
Causative factor	Melanin deposition	Proliferation of melanocytes	Proliferation of keratinocytes & melanocytes	Uncontrolled growth of melanocytes
Histopathologic features	Melanin accumulation without an increase in melanocytes.	Polygonal & epithelioid nevus cells in the superficial. Cytoplasm transparent to light stained.	Many dendritic melanocytes, processes containing melanin & melanophagocytes in all strata of epithelium.	Large, vesicular nucleus & prominent nucleoli. Aggregated into sheets or alveolar groups. Neurotropic or desmoplastic configurations.