Combined utility of p16 and BRAF V600E in the evaluation of spitzoid tumors: Superiority to PRAME and correlation with FISH.
J Cutan Pathol
; 50(2): 155-168, 2023 Feb.
Article
em En
| MEDLINE
| ID: mdl-36261329
ABSTRACT
BACKGROUND:
Spitzoid melanocytic neoplasms are diagnostically challenging; criteria for malignancy continue to evolve. The ability to predict chromosomal abnormalities with immunohistochemistry (IHC) could help select cases requiring chromosomal evaluation.METHODS:
Fluorescence in situ hybridization (FISH)-tested spitzoid neoplasms at our institution (2013-2021) were reviewed. p16, BRAF V600E, and preferentially expressed antigen in melanoma (PRAME) IHC results were correlated with FISH.RESULTS:
A total of 174 cases (1.9F1M, median age 28 years; range, 5 months-74 years) were included; final diagnoses Spitz nevus (11%), atypical Spitz tumor (47%), spitzoid dysplastic nevus (9%), and spitzoid melanoma (32%). Sixty (34%) were FISH positive, most commonly with absolute 6p25 gain (RREB1 > 2). Dermal mitotic count was the only clinicopathologic predictor of FISH. Among IHC-stained cases, p16 was lost in 55 of 134 cases (41%); loss correlated with FISH positive (p < 0.001, Fisher exact test). BRAF V600E (14/88, 16%) and PRAME (15/56, 27%) expression did not correlate with FISH alone (p = 0.242 and p = 0.359, respectively, Fisher exact test). When examined together, however, p16-retained/BRAF V600E-negative lesions had low FISH-positive rates (5/37, 14%; 4/37, 11% not counting isolated MYB loss); all other marker combinations had high rates (56%-75% of cases; p < 0.001).CONCLUSIONS:
p16/BRAF V600E IHC predicts FISH results. "Low-risk" lesions (p16+ /BRAF V600E- ) uncommonly have meaningful FISH abnormalities (11%). PRAME may have limited utility in this setting.Palavras-chave
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Neoplasias Cutâneas
/
Nevo de Células Epitelioides e Fusiformes
/
Melanoma
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Estados Unidos