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Updated: Oct 25, 2025
A Robust Discovery Platform for the Identification of Novel Mediators of Melanoma Metastasis
Published on: March 8, 2022
Diffuse PRAME Expression Is Highly Specific for Thin Melanomas in the Distinction from Severely Dysplastic Nevi but
Maximilian Gassenmaier1, Matthias Hahn1, Gisela Metzler1
1Department of Dermatology, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany.
Background:
PReferentially expressed Antigen in MElanoma (PRAME) immunohistochemistry is increasingly used as diagnostic adjunct in the evaluation of melanocytic tumors. The expression and prognostic significance of PRAME in melanomas ≤1.0 mm and its diagnostic utility in the distinction from severely dysplastic compound nevi (SDN) have not been studied.
Methods:
We investigated and compared the immunohistochemical PRAME expression in 70 matched thin metastasizing and non-metastasizing melanomas and 45 nevi from patients with long-term follow-up (35 SDN and 10 unequivocally benign compound nevi).
Results:
Diffuse PRAME staining in >75% of lesional epidermal and dermal melanocytes identified 58.6% of thin melanomas but did not distinguish metastasizing from non-metastasizing melanomas (p = 0.81). A superficial atypical melanocytic proliferation of uncertain significance, in which the final diagnostic interpretation favored a SDN was the only nevus with diffuse PRAME expression (1/45). Melanomas and SDN with PRAME immunoreactivity exhibited different staining patterns. Most melanomas (67.6%) showed uniform PRAME expression in the in situ and invasive component, whereas most SDN (81.0%) showed a decreasing gradient with depth.
Conclusion:
Diffuse intraepidermal and dermal PRAME staining is highly specific for melanomas in the distinction from SDN. PRAME expression is not a prognostic biomarker in melanomas ≤1.0 mm.
Insights
Preferentially expressed Antigen in MElanoma (PRAME) immunohistochemistry is specific for distinguishing melanomas from severely dysplastic nevi. PRAME expression does not predict prognosis in thin melanomas.
Area of Science:
- Dermatopathology
- Oncology
- Immunohistochemistry
Background:
- Preferentially expressed Antigen in MElanoma (PRAME) immunohistochemistry is a valuable tool for diagnosing melanocytic tumors.
- The role of PRAME in thin melanomas (≤1.0 mm) and its ability to differentiate from severely dysplastic nevi (SDN) remain unclear.
Purpose of the Study:
- To evaluate PRAME expression in thin melanomas and compare it with SDN.
- To determine if PRAME expression has prognostic significance in thin melanomas.
Main Methods:
- Immunohistochemical PRAME expression was analyzed in 70 thin melanomas and 45 nevi (35 SDN, 10 benign nevi).
- Metastasizing and non-metastasizing melanomas were compared.
- Staining patterns in melanomas and SDN were characterized.
Main Results:
- Diffuse PRAME staining identified 58.6% of thin melanomas but did not differentiate between metastasizing and non-metastasizing tumors.
- Only one nevus (SDN) showed diffuse PRAME expression.
- Melanomas typically exhibited uniform PRAME staining, while SDN showed a decreasing gradient.
Conclusions:
- Diffuse PRAME staining is highly specific for identifying melanomas and distinguishing them from SDN.
- PRAME is not a prognostic biomarker for melanomas ≤1.0 mm.
