Smooth muscle tumors of the gastrointestinal tract and retroperitoneum.A pathologic analysis of 100 cases

Abstract

One hundred smooth muscle tumors arising in the gastrointestinal tract and retroperitoneum were reviewed in an attempt to define criteria for the diagnosis of leiomyosarcoma in these sites. On the basis of aggressive behavior, 56 of these neoplasms were diagnosed as leiomyosarcoma. Mitoses were found to be the most useful indicator of malignancy; all of the tumors with five or more mitoses/10 HPF behaved aggressively and smooth muscle tumors with this degree of mitotic activity should be diagnosed as leiomyosarcoma. A paucity of mitoses, however, is no assurance of benignity as nearly 40% of the leiomyosarcomas in this series had fewer than five mitoses/10 HPF. Tumor cell necrosis was closely associated with aggressive behavior even when mitoses were infrequent and it is doubtful that benign smooth muscle tumors develop extensive tumor cell necrosis. In the absence of the requisite number of mitoses or tumor necrosis, it is difficult to distinguish some leiomyosarcomas from leiomyomas, but tumor size, cellularity and cellular atypia may be helpful parameters when assessed together. The importance of these criteria in different anatomical sites is discussed. It is emphasized that the criteria for the diagnosis of leiomyosarcoma of the uterus do not apply to non-uterine smooth muscle tumors. The actuarial 2-year survival rate was as follows: gastric leiomyosarcoma, 40%; small intestinal leiomyosarcoma, 60%; and retroperitoneal leiomyosarcoma, 16%.

Cytomorphology of gastrointestinal stromal tumours: a comprehensive study

“…Similarly, Ranchod and Kempson observed that marked cytologic atypia was not a frequent finding in leiomyosarcomas but when present, was found only in malignant tumours and was associated with abundant mitoses. 13 Most leiomyomas in their study showed mild or no atypia, a feature shared by very low risk and low risk tumours in the present study. Also in the study by Evans both low and high grade leiomyosarcomas showed mostly moderate degree of nuclear atypia.…”

“…Most of the earlier studies have expressed MR/10HPFs as originally described by Ranchod and Kempson. 8 They advocated examination of 5 sets of 10 HPFs and the set with highest mitotic count was used as the final rate. This method allows for regional variation in MR that is typical of GIST.…”

Ki67 and p53 in gastrointestinal stromal tumors - GIST

“…GIST can occur along the gastrointestinal tract, most commonly in stomach (70%) (10,28,29) and small intestine (20%-25%) (10,28,31) . The clinical presentation depends on the site of the tumor and almost 20% of them may be asymptomatic.…”

A Rare Case of a Retroperitoneal Leiomyoma in the Obturator Fossa

“…In a study of 688 primary retroperitoneal tumors, 1% -2% were leiomyomas (6). Other studies have shown that most retroperitoneal smooth muscle tumors are malignant (7,8). A review of the literature from 1966 to 2008 confirmed that retroperitoneal myomas are extremely rare (9).…”