Aims: To investigate the histogenesis of paratesticular adenomatoid tumour
by use of immunohistochemical markers for a variety of carcinomas and mesot
helioma, Methods and results: Immunohistochemical staining of sections from
12 cases of paratesticular adenomatoid tumour was undertaken using primary
antibodies to antigens expressed by benign epithelial cells and carcinoma
(cytokeratin AE1/AE3, cytokeratin 34BE312, epithelial membrane antigen, MOC
-31, Ber-EP4, CEA, B72.3, LEA.135, Leu Mi), stromal and vascular markers (v
imentin, CD34, factor VIII), and mesothelioma-associated antigens (thrombom
odulin, HBME-1, OC 125) and p53 protein. There was absence of immunohistoch
emical expression of epithelial/ carcinoma markers MOC-31, Ber-EP4, CEA, B7
2.3, LEA.135, Leu M1 and to factor VIII and CD34. All tumours expressed cyt
okeratin AE1/AE3, epithelial membrane antigen and vimentin, with weak expre
ssion of cytokeratin 34BE12 in 25% of tumours. Each tumour showed expressio
n of thrombomodulin, HBME-1 and OC 125 in a membranous distribution, p53 pr
otein expression was not detected.
Conclusions: The immunohistochemical profile of paratesticular adenomatoid
tumour is strongly supportive of a mesothelial cell origin.