Smooth-muscle tumors of the rectum in Japanese

Anorectal leiomyosarcomas

“…Neuman 19 believes that a benign lesion may ultimately become malignant, and multiple instances of late recurrence and spread of locally excised leiomyomas of the rectum have been reported. 5,[19][20][21][22][23][24] Since examination of portions of a tumor may not be representative of the true malignant behavior of the entire lesion, it is possible that, as in our case 2, some "leiomyomas" probably have evidence of malignancy and were originally misdiagnosed histologically. 20 Other investigators suggest that all tumors with increased cellularity should be regarded as potentially malignant, even when without mitosis or cellular atypism.…”

“…17 For anal leiomyosarcoma, i.e., leiomyosarcoma of the terminal 2-3 cm of the large intestine, the total number of cases in the English-language literature is probably fewer than 15 and none were reported from Taiwan. [3][4][5][6][7][8][9][10][11][12][13] Most rectal leiomyosarcomas are seen in the lower third and presenting symptoms are constipation, rectal pain, pressure sensation, dysuria, difficult defecation, or obstruction. However, when the lesions produce symptoms, they are difficult to distinguish from those caused by epidermoid carcinoma.…”

“…20 Other investigators suggest that all tumors with increased cellularity should be regarded as potentially malignant, even when without mitosis or cellular atypism. 5,14,25 The spread of these tumors is principally local and hematogenous. Evans 26 noted that recurrence of tumor was significantly more frequent in patients with highgrade leiomyosarcoma, and intervals to both recurrence and metastasis were longer in those with the low-grade.…”

“…The majority, according to medical reports, arise from the posterior and lateral walls of the anorectum. 2,5,23 They may be as small as 1 cm in diameter or may be as large as a grapefruit. They are firm tumors that may grow intraluminally, submucosally, or both ways.…”

“…2 Anal leiomyosarcomas are reported to be even more rare, with only 15 cases reported in the Englishlanguage literature up to 1996. [3][4][5][6][7][8][9][10][11][12][13] We report two cases of anorectal leiomyosarcoma with a discussion of the literature, as well as a commentary on some developments pertinent to the subject. The mucosal aspect of the rectum shows the tumor chiefly located submucosally (open arrows) and straddled over the dentate line.…”