Small Intestinal Stromal Tumors:A Clinicopathologic Study of 20 Cases With Immunohistochemical Assessment of Cell Differentiation and the Prognostic Role of Proliferation Antigens

Gastrointestinal Stromal Tumours

“…To differentiate between clinically benign and malignant tumors originating from various sites, several large clinicopathologic studies of GISTs have accepted the contention that tumor size more than 5 em will have unfavourable prognosis [7,[10][11][12]. The size of the tumor has also been correlated with the histopathological findings in deciding the nature and their metastatic potential [8,9,13].…”

“…The importance of mitotic figures have been accepted uniformly by various authors to separate benign from malignant lesions, but with variable number. However most workers considered unfavourable outcome of the case if the number of mitotic figures were more than 5 in 50 high power fields [2][3][4][5][6][7]16]. Poor prognosis was also predicted, if in addition to the criteria of the tumor size it showed high cellularity, absence of predominant organoid growth pattern and absence of skeinoid fibres on microscopic examination.…”

“…Poor prognosis was also predicted, if in addition to the criteria of the tumor size it showed high cellularity, absence of predominant organoid growth pattern and absence of skeinoid fibres on microscopic examination. Features, such as severe nuclear pleomorphism, areas of necrosis and high mitotic figures invariably favoured malignancy [6,7,11,15]. Unfortunately all these conventional features and special stains do not help much in regard to their cellular lineage e.g.…”

“…Of late, these tumors showed interesting divergent cellular pathways suggestive of smooth muscle, neural and immature mesenchymal differentiations based on the newer diagnostic techniques, such as immunochemistry,and electron microscopy (EM). The histological appearances alone do not reliably reflect the accurate immunophenotypes [5][6][7]. The classiftcation of Gastrointestinal stromal tumors (GISTs) has been the subject of considerable debate, however based on IRC and EM studies carried by numerous authors, these tumors are divided in four major groups [3,8].…”

“…Less commonly, tumors reveal dual differentiation in the third group, and lastly a group of immature mesenchymal tumors lacking differentiation toward either cell types. Some workers use the term GISTs only for undifferentiated stromal tumors of GIT, lacking differentiation towards either cell types [3,7].…”