A Case Series on Intraoral Blue Nevi with a Literature Review-Based Clinico-Pathologic Comparison of Intraoral Blue Nevi with Other Oral Melanocytic Nevi

Nevi are pigmented lesions of bluish-black colour that may occasionally occur in the oral cavity. Out of several oral melanocytic nevi (OMN), blue nevi are significant as some variants are diagnostically challenging due to histopathological overlap with malignant melanoma. The aim of the present report was to present the clinico-pathologic characteristics of 8 new cases of intraoral common blue nevi and 22 OMN. A literature review-based comparison of the clinico-pathological characteristics of intraoral blue nevi with intramucosal nevi is presented. Analysis of the clinico-pathologic characteristics of eight common blue nevi revealed that they are generally small lesions of less than 1 cm in size and are of bluish-black colouration. These lesions were commonly identified in adults (88%), with a female predilection. The hard palate was the most common site of occurrence. These findings could be collaborated with the findings observed in the literature review. It was also revealed that a common blue nevus was the second most common lesion among all OMN. The intraoral common blue nevi included in the present series did not show recurrences or undergo malignant transformation after being followed up for up to 15 years. Unlike a common blue nevus, the literature reveals that a cellular blue nevus or its atypical variant is more diagnostically challenging, while a diagnosis of an epithelioid blue nevus should be followed up with investigations to exclude Carney complex. In conclusion, this case series and literature review reveal that OMN, including intraoral common blue nevi, are small indolent lesions with extremely low malignant transformation potential. A significantly smaller size, well-defined margins and lack of variegations in colour are all features that could be used as clues to differentiate intraoral common blue nevi from mucosal malignant melanoma. However, the diagnosis needs to be confirmed with histopathology.