Association of Papillary Thyroid Carcinoma with GIST-a Case Series.

Gastrointestinal stromal tumours (GIST) are the most common gastrointestinal mesenchymal tumours of the gastrointestinal tract. They are diagnosed by the expression of markers like CD 117, CD 34, DOG-1 and PDGFRA. The identification of these mutations has resulted in a better understanding of their oncogenic mechanisms. Few studies have shown the high incidence of a second malignancy including papillary thyroid cancer (PTC) in known patients of GIST. Literature review on pathogenesis of GIST and PTC showed that PTC targeting Protein Kinase C theta (PKCθ) plays role in both PTC and GIST. Further studies have also shown that, apart from somatic and familial gastrointestinal stromal tumours, PDGFRA is associated with many other malignancies including PTC. These studies explain the common genetic pathway involved in the development of GIST and PTC in same patient. In spite of common genetic association between GIST and other malignancies, none of the standard protocols recommends screening for second malignancy. In this article, we present the details of four patients who had associated GIST and PTC at the same time or developed during follow-up.