# Oral amelanotic melanoma in a 73-year-old patient: A rare case report and literature review

## TL;DR

A rare case of non-pigmented oral melanoma in a 73-year-old woman is reported, highlighting diagnostic challenges and the importance of immunohistochemistry.

## Contribution

This is the first report of TRP-2 immunoexpression in oral amelanotic melanoma and the sixth such case in Latin America.

## Key findings

- Oral amelanotic melanoma in older adults is rare and often misdiagnosed due to lack of pigmentation.
- Immunohistochemistry confirmed the diagnosis and revealed TRP-2 positivity, a first in this subtype.
- The patient's case highlights the need for a detailed immunohistochemical panel to avoid diagnostic errors.

## Abstract

Oral melanoma is an aggressive neoplasm that predominantly affects older adults. The amelanotic subtype is exceedingly rare, and its diagnosis is challenging due to the absence of pigmentation. Herein, we report a rare case of oral amelanotic melanoma in an older adult, discussed in light of the available literature. A 73-year-old Brazilian female patient presented with pain and discomfort in the left transverse palatal rugae. Clinically, the lesion appeared as a single, sessile, dome-shaped nodule with a coloration similar to the adjacent mucosa. Histopathological examination revealed a spindle-cell malignant neoplasm with epithelioid nests within a fibrous stroma, lacking melanin pigmentation. Immunohistochemistry was positive for pan-cytokeratin AE1/AE3, vimentin, S100 protein, Melan-A, SOX10, NSE, and TRP-2, with a high Ki-67 index. The patient died two months after diagnosis. A review of PubMed, Scopus, Embase, and Web of Science identified 35 cases of oral amelanotic melanoma in older adults, predominantly females (n=20/57.1%) in their 60s (n=16/45.7%). This report documents the sixth case of oral amelanotic melanoma in older adults from Latin America. Clinically, the case was challenging because it mimicked a non-neoplastic proliferative process and, microscopically, presented as an amelanotic variant. An immunohistochemical panel is recommended to avoid diagnostic pitfalls; this is the first report of TRP-2 immunoexpression in oral amelanotic melanoma.