# Quadruple Negative Metastatic Melanoma With Gain of SOX-11 Expression and TERT Mutation

## TL;DR

This paper presents a rare case of melanoma that lost key markers but gained SOX-11, highlighting challenges in diagnosing metastatic melanoma.

## Contribution

The case demonstrates a novel expression pattern of SOX-11 in a quadruple-negative melanoma with a TERT mutation.

## Key findings

- The melanoma case showed loss of S100, SOX-10, HMB45, and MART-1 markers.
- SOX-11 expression was gained in the tumor, which is unusual for melanoma.
- The tumor also had a TERT mutation, adding to its diagnostic complexity.

## Abstract

Malignant melanoma is a common and aggressive skin cancer with a high incidence of metastases. Diagnosis is usually straightforward, based on a combination of histomorphology and immunohistochemistry. However, metastatic melanoma is notorious for its phenotypic diversity and loss of differentiation markers. Through recent developments in diagnostic immunohistochemistry and molecular pathology, several new markers are identified to be of use in confirming melanoma diagnosis, especially in undifferentiated and dedifferentiated cases. Here we report a challenging case of a 59-year-old male with splenic metastatic melanoma which revealed a loss of four diagnostic melanocytic markers including S100, SOX-10, HMB45, and MART-1, but a gain of SOX-11.