Rectal leiomyosarcoma, late complication of pelvic radiotherapy.

Abstract

Rectalleiomyosarcoma(LMS)isararediseaseoccupyinglessthan 0.1 % of colorectal tumors [1]. Even if we know therelation between radiation and colorectal carcinomas, the re-lation between radiation and LMS is not certain because ofuncommon existence. Up to date, rectal LMS after pelvicradiotherapy was detected in four patients. Our case is thefifth patient in literature.A75-year-oldfemalepatientwasadmittedtoourclinicwithacomplaint of change in bowel habits. In history, she has aunilateral oophorectomy with diagnosis of ovarian maligncystic lesion 35 years ago, and afterwards, she has undergoneradiotherapy of 15 days duration. Her physical examinationwas normal. In laboratory assessments, anemia and occultblood in her stool were detected. Her CA-125 level waselevated; other tumor marker (CEA, CA19-9, AFP, CA15-3)levelswereallnormal.Therewerenotanypathologicfindingsin transabdominal ultrasound examination, but a mass lesionin the rectum with a diameter of 7 cm was detected withabdominal computerized tomography. During endoscopy, at9 to 10 cm proximal to the anus, a tumoral lesion obliteratingintestinal lumen was seen and biopsy was taken. The histo-pathologicalexaminationofthebiopsyspecimenrevealedthatit is a LMS. Tumor cells stained positively for vimentin andactin but negatively for PanCK. Metastasis examination wasdone and no metastasis was detected.After informing the patient and completing preoperativepreparations, low anterior resection was performed. Therewere not any complications in the postoperative period.Patient was discharged at the sixth day of operation. In histo-pathologicalexamination,thetumorsizewasreported8cmindiameter. Fourteen lymph nodes were removed at the opera-tionandmetastasiswasnotdetected.Tumorcellswerestainedpositively for vimentin, but negatively for pancytokeratin,S100,beta-catenin,CD3,CD117,anddesmin.Fifteenmitoseswere recognized at ten times magnification.Ten percent of smooth muscle tumors are LMS.Leiomyosarcoma of the gastrointestinal tract is generally lo-cated at the stomach or small bowel, rarely at the colon orrectalregion.Itoriginatesfromthemuscularmucosaorproprialayer of the gastrointestinal tract. Whereas radiotherapy is awell-known risk factor for colon carcinoma, for colorectalLMS, its role is not well defined. Because of small numberof patients, it is difficult to show the correlation in between.Sarcomas after radiotherapy account for 0.5–5.5 % of allsarcomas. Most of them are osteosarcoma and fibrosarcoma.Differentiation of sarcoma as primary tumor or secondary toradiotherapy is important for clinical and academical ap-proaches. But there is not any strict criterion for differentia-tion. Cahan introduced some criteria for this reason whichwere revised by Huvos afterwards [2]. With regard to theserevised criteria, if patient has history of radiotherapy, if diag-nosed sarcoma is at the same region of radiotherapy, if sarco-ma is diagnosed long after radiotherapy, and if sarcoma isdiagnosedhistologically,onecansaythatsarcomaisrelatedtoradiotherapy. Paulino et al. investigated secondary cancerdevelopment after exposure to radiotherapy due to malignantdiseases. They reported malignant tumor development afterradiotherapyat5.4%ofpatients,andat71%ofthesepatients,tumor development is at the same side of radiotherapy.Secondary sarcomas were detected 4.6–33.6 years (averageof 10.1) after the first tumor [3]. In another study, secondarycancer development period after exposure to radiotherapy atadult agehood is found to be 5–40 years interval.