In:
Histopathology, Wiley, Vol. 71, No. 4 ( 2017-10), p. 511-521
Abstract:
Accurate classification of salivary gland neoplasms may be challenging, owing to morphological overlap, particularly in small biopsies. Recurrent translocations involving the high‐mobility group AT ‐hook 2 ( HMGA 2) gene are present in a subset of pleomorphic adenomas ( PA s) and carcinoma ex‐pleomorphic adenomas ( CA ex‐ PA s). The aim of this study was to evaluate immunohistochemical HMGA 2 expression in 225 salivary gland tumours, including 56 PA s, 37 CA ex‐ PA s, and 132 potential histological mimics, to determine its diagnostic utility. Methods and results HMGA 2 expression was identified in 19 PA s (33.9%) and nine CA ex‐ PA s (24.3%). Expression was strong and diffuse throughout all PA s, and in four of nine positive CA ex‐ PA s. In five CA ex‐ PA s, HMGA 2 showed weak‐to‐strong multifocal staining within the carcinomatous component, and strong diffuse HMGA 2 expression in the residual PA . Among histological mimics, six de‐novo salivary duct carcinomas (28.5%), three epithelial–myoepithelial carcinomas (33.3%) and one case each of myoepithelioma and basal cell adenoma expressed HMGA 2. Fluorescence in‐situ hybridization for HMGA 2 rearrangement performed on a subset of tumours that showed diffuse HMGA 2 expression in PA s and CA ex‐ PA s was frequently associated with rearrangement of the HMGA 2 locus, whereas cases of de‐novo salivary duct carcinoma, or CA ex‐ PA with limited or no HMGA 2 expression, had an intact HMGA 2 locus. Conclusions HMGA 2 expression is a highly specific (96.2%), but low‐sensitivity (29.8%), marker for PA and CA ex‐ PA when compared with histological mimics, and is frequently associated with rearrangement of the HMGA 2 locus.
Type of Medium:
Online Resource
ISSN:
0309-0167
,
1365-2559
DOI:
10.1111/his.2017.71.issue-4
Language:
English
Publisher:
Wiley
Publication Date:
2017
detail.hit.zdb_id:
2006447-0
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