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Updated: Aug 14, 2026
A Melanoma Patient-Derived Xenograft Model
Published on: May 20, 2019
Pigmented epithelioid melanocytoma (animal-type melanoma): An institutional experience
Michael J Bax1, Marc D Brown1, Paul G Rothberg2
1Department of Dermatology, University of Rochester School of Medicine, Rochester, New York.
Background:
Pigmented epithelioid melanocytoma (PEM) is an uncommon, recently described entity with unknown biologic behavior. There is a high rate of regional metastases, but limited evidence of distant metastases or disease-related death.
Objective:
We sought to report our series of patients given a diagnosis of PEM at our institution and provide mutational analysis of genes commonly implicated in melanoma in 2 cases.
Methods:
The pathology database was queried for cases of PEM diagnosed at the University of Rochester. Charts were reviewed for follow-up information. Mutational analysis of melanoma-associated genes was performed on 2 cases.
Results:
Nine cases of PEM were retrieved in a 10-year retrospective review. Five patients underwent sentinel lymph node biopsy with 3 of 5 having a positive sentinel lymph node. All 9 patients are alive and disease-free with average follow-up of 38.75 months. Two tumors were tested for common melanoma-associated mutations, and were negative, except for a telomerase reverse transcriptase promoter deletion detected in 1 sample. The deletion has not been associated with melanoma, and therefore its biologic significance is unclear.
Limitations:
Small sample size, retrospective nature, and single institution experience are limitations.
Conclusions:
PEM appears to have an indolent behavior. However, currently the evidence is too limited to provide insight into its true biologic potential.
Insights
Pigmented epithelioid melanocytoma (PEM) shows indolent behavior, with no disease-related deaths observed in a small retrospective study. Further research is needed to fully understand its biologic potential and confirm these findings.
Area of Science:
- Dermatopathology
- Oncology
- Genetics
Background:
- Pigmented epithelioid melanocytoma (PEM) is a rare neoplasm with uncertain biologic behavior.
- While regional metastases are common, distant spread and disease-related mortality are infrequently reported.
Purpose of the Study:
- To report a case series of PEM diagnosed at a single institution.
- To conduct mutational analysis of melanoma-associated genes in select PEM cases.
Main Methods:
- Retrospective review of nine PEM cases diagnosed over a 10-year period.
- Sentinel lymph node biopsy performed in five patients.
- Sanger sequencing and PCR-based analysis of common melanoma-associated genes in two tumors.
Main Results:
- All nine patients remain alive and disease-free with a mean follow-up of 38.75 months.
- Three of five patients with sentinel lymph node biopsy had positive nodes.
- Mutational analysis revealed no common melanoma mutations, with one case showing a telomerase reverse transcriptase promoter deletion of unclear significance.
Conclusions:
- PEM exhibits an apparently indolent clinical course.
- Limitations include small sample size and retrospective design.
- More extensive data is required to ascertain the true biologic potential of PEM.
