Malignant Melanocytic Matricoma and Criteria for Malignancy

Colton B. Nielson,Vladimir Vincek

doi:10.4236/ojpathology.2018.83011

Abstract

Melanocytic matricoma is a very rare adnexal tumor that recapitulates the anagen hair follicle bulb. Few cases of malignant melanocytic matricoma have been reported, thus criteria for malignant potential have not been previously reviewed. We report a case of an 81 year old male that was originally diagnosed as atypical melanocytic matricoma. The site was re-excised with a small focus of residual tumor, but all margins were negative. The re-excision site healed without complication. However, two years after the original biopsy, a new 8 mm firm nodule appeared at the re-excision site, which was subsequently diagnosed as malignant melanocytic matricoma (MMM). In the following paper we will report a new case of MMM and review potential criteria that could be used in the future to establish malignant potential.

Highlights

Melanocytic matricoma is a rare cutaneous neoplasm that typically presents clinically as a pigmented papule on sun exposed skin in the elderly [1]
We report a case of an 81 year old male that was originally diagnosed as atypical melanocytic matricoma
The site was re-excised with a small focus of residual tumor, but all margins were negative

Summary

Introduction

Melanocytic matricoma is a rare cutaneous neoplasm that typically presents clinically as a pigmented papule on sun exposed skin in the elderly [1]. Clinical behavior of the tumor has been difficult to predict. Seven cases of a malignant variant of melanocytic matricoma have been reported [4] [5] [6] [7] [8]. This entity is important to recognize as melanocytic matrical carcinoma can mimic melanoma when melanocytic proliferations or melanin pigment are prominent [8]. We report an additional case of malignant melanocytic matricoma and discuss criteria that might be useful to predict malignant potential

Clinical Presentation

Histopathologic Findings

Discussion

Conclusion