Which of the following markers is specific for gastro-intestinal stomal tumor (GIST) -

lmmunohistochemistry o Following markers are present in GISTs: i) CD 117 (c kit) -->95% ii) CD 34 --> 70% iii) Smooth muscle actin 5% CD 117 (c kit) is considered the most specific marker o CD 117 (c kit) immunoreactivity is the best defining feature of GISTs distinguishing them from true smooth muscle tumors (leiomyoma) and tumors arising from neural crest. o Although CD 117 (c kit) is considered the most specific marker for GIST, it is not pathognomonic of GIST as other tumors may also express CD 117. These tumors include mast cell tumor, germ cell tumors (seminomas), leukemias, malignant melanoma, angiolipomas, and some sarcomas. REF: ROBBINS pathology 10th edition