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Diffuse PRAME Expression Is Highly Specific for Thin Melanomas in the Distinction from Severely Dysplastic Nevi but Does Not Distinguish Metastasizing from Non-Metastasizing Thin Melanomas

Maximilian Gassenmaier, Matthias Hahn, Gisela Metzler, Jürgen Bauer, Amir Sadegh Yazdi, Ulrike Keim, Claus Garbe, Nikolaus Wagner & Stephan Forchhammer

abstract

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 ( = 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.
   
citation Gassenmaier M, Hahn M, Metzler G, Bauer J, Yazdi A S, Keim U, Garbe C, Wagner N, Forchhammer S. Diffuse PRAME Expression Is Highly Specific for Thin Melanomas in the Distinction from Severely Dysplastic Nevi but Does Not Distinguish Metastasizing from Non-Metastasizing Thin Melanomas. Cancers (Basel) 2021; 13:.
   
type journal paper/review (English)
date of publishing 31-07-2021
journal title Cancers (Basel) (13/15)
ISSN print 2072-6694
PubMed 34359765
DOI 10.3390/cancers13153864