In:
Journal of Cutaneous Pathology, Wiley, Vol. 50, No. 2 ( 2023-02), p. 155-168
Abstract:
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 (1.9F:1M, 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.
Type of Medium:
Online Resource
ISSN:
0303-6987
,
1600-0560
Language:
English
Publisher:
Wiley
Publication Date:
2023
detail.hit.zdb_id:
2018100-0
