Classification of submucosal tumors in the gastrointestinal tract

Abstract

This review is part two of three, which will present an update on the classification of gastrointestinal submucosal tumors. Part one treats of the diagnosis and part three of the therapeutic methods regarding gastrointestinal submucosal tumors. In the past there has been some confusion as to the classification of gastrointestinal submucosal tumors. Changes in classifications have emerged due to recent advances in mainly immunohistochemistry and electron microscopy. The aim of this paper is to update the reader on the current classification. Literature searches were performed to find information related to classification of gastrointestinal submucosal tumors. Based on these searches the twelve most frequent submucosal tumor types were chosen for description of their classification. The factors that indicate whether tumors are benign or malignant are mainly size and number of mitotic counts. Gastrointestinal stromal tumors are defined mainly by their CD117 positivity. In the future, there should be no more confusion between gastrointestinal stromal tumors and other types of submucosal tumors.

Figure 1

Exophytic leiomyosarcoma of the ileum, measuring 6 cm x 5 cm x 3 cm. A fibrin coated mucosa with stigmata of hemorrhage and discolorations of the adjacent mucosa can be seen (Courtesy by S Duun).

Figure 2

Cut surface of the leiomyosarcoma presented in Figure 1, showing a possible necrosis and a white, fish-flesh-like color, as typical for sarcomas. The surface did not bulge on incision (Courtesy by S Duun).

Figure 3

The leiomyosarcoma presented in Figures 1 and 2. It is of low malignancy, but shows nuclear atypia, pleomorphism and mitoses. (HE, x 100) (Courtesy by S Duun).

Figure 4

Histological findings of a GIST showing a positive CD117 immunohisto-chemical reaction. (× 200) (Courtesy by B Vainer).