Specificity of DOG1 (K9 clone) and protein kinase C theta (clone 27) as immunohistochemical markers of gastrointestinal stromal tumour.
OBJECTIVE
DOG1 and protein kinase C (PKC) theta are both sensitive immunohistochemical markers of gastrointestinal stromal tumour (GIST). However, there are conflicting data regarding the specificity of the most commonly used PKC theta antibody (clone 27), and there are no existing data regarding the specificity of the only known commercially available DOG1 antibody (K9 clone) at the time of writing. This study's aim was to characterize the immunoreactivity patterns of both monoclonal antibodies amongst a wide range of neoplasm types including, in particular, histological mimics of GIST.


RESULTS
Immunohistochemistry for DOG1 and PKC theta was performed on whole tissue sections from 23 different neoplasm types (total of 125 cases). Ten of these neoplasm types showed CD117 immunopositivity. Only three (Ewing's sarcoma, glomus tumour and synovial sarcoma) of the 23 neoplasm types showed DOG1 immunopositivity, and such positivity was often focal and weak in intensity. In contrast, all but four (ganglioneuromas, leiomyomas, desmoplastic small round cell tumours and PEComa/angiomyolipomas) of the 23 neoplasm types showed PKC theta immunopositivity.


CONCLUSIONS
Compared with CD117, DOG1 (using the K9 antibody) is a more specific marker, whereas PKC theta (using the clone 27 antibody) is a considerably less specific immunohistochemical marker for GIST.
Wong
Newton A C S
NA
Department of Histopathology, Bristol Royal Infirmary, Marlborough Street, Bristol, UK. nacs.wong@bristol.ac.uk
Shelley-Fraser
Golda
G
D000075369:Anoctamin-1; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor / Q000378:metabolism*; D018118:Chloride Channels; D003937:Diagnosis, Differential; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis* / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D009369:Neoplasms / Q000175:diagnosis / Q000378:metabolism; D015588:Observer Variation; D011493:Protein Kinase C / Q000378:metabolism*; D000074121:Protein Kinase C-theta; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D012680:Sensitivity and Specificity
C476213:ANO1 protein, human; D000075369:Anoctamin-1; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D018118:Chloride Channels; D007527:Isoenzymes; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D019009:Proto-Oncogene Proteins c-kit; C076233:PRKCQ protein, human; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta