a collision tumor is defined by the coexistence of two adjacent , but histologically distinct tumor components . this tumor is considered a multiple synchronous tumor in a single organ , because these components are separated from each other by stroma without histologic admixture ( 1 ) . collision tumors have been reported in various organs , such as esophagus , stomach , colon , lung , skin , thyroid gland , breast , ovary , and uterus ( 2 ) . previously reported uterine collision tumors are mainly composed of two different histological components ; serous or endometrioid adenocarcinoma , and sarcoma or neuroendocrine tumor ( 2 - 8 ) . in this report the tumor is composed of three distinct histologic components , endometrioid adenocarcinoma , papillary serous carcinoma , and malignant mixed mllerian tumor . on november 14 , 2003 , a 70-yr - old female visited our hospital due to abnormal uterine bleeding and abdominal pain . her gynecologic history included seven full - term pregnancies , six normal deliveries , one still birth , and two abortions . menarche had occurred at the age of 17 yr and menstruation was on a regular basis . menopause occurred at the age of 50 yr , and she has never received hormone replacement therapy . transvaginal ultrasonography revealed a 9.2  5.9 cm - sized mass with a mixed echogenic shadow in the uterus , suggesting an endometrial malignancy . pelvic computed tomography displayed a large mass , which occupied the entire endometrial cavity with suspicious infiltration to the myometrium and parametrial soft tissue . the adjacent organs , such as urinary bladder , rectum , and sigmoid colon , were free of tumor extension . however , the nodular infiltration of omentum was noted , suggesting the possible omental seeding . magnetic resonance imaging revealed poorly enhancing inhomogeneous mass within the uterine cavity with tumor infiltration around the uterus with no definitive evidence of lymphadenopathy or extension to the adjacent organs . the laboratory test was within normal limit for routine blood count , electrolytes , and chemistry . the tumor marker , ca125 , was elevated to 1,132 u / ml ( reference range 0.1 - 35 u / ml ) . on november 17 , 2003 there was no evidence of distant metastasis on the surface of liver , spleen , diaphragm and peritoneum . however , suspicious metastatic nodules were found on omentum and the surface of sigmoid colon . the patient underwent total abdominal hysterectomy with bilateral salphingo - oophorectomy , total omentectomy , removal of the mass on the surface of sigmoid colon , bilateral pelvic and para - aortic lymph node dissection , and appendectomy . intraperitoneal chemotherapy with paclitaxel was performed during operation due to the suspicious metastatic nodules on omentum and serosa of sigmoid colon . adjuvant chemotherapy ( paclitaxel 175 mg / m , epirubicin 60 mg / m , and carboplatin auc 6 , every 3 weeks , 6 cycles ) and radiation therapy ( 55 gy , 6 weeks ) were also performed . she had been given non - steroidal aromatase inhibitor ( letrozole ) orally for maintenance therapy , and remained healthy with no evidence of recurrence for 8 yr after surgery . on gross examination , the uterus was enlarged and measures 12  6.5  6 cm in dimensions and 325 gm in weight . on opening of the uterus , there were three separated masses arising from the endometrium ( fig . 1 ) . the first was a large pedunculated polypoid mass at the anterior wall of the corpus , measuring 8  7  4.7 cm in dimensions . the surface of the first tumor displayed multifocal hemorrhage and necrotic friable debris , and the cut surface showed solid and fish - flesh appearance . the second was a broad based and protruding mass at the fundus of the corpus , measuring 5  4  1 cm in dimensions . by sectioning the second tumor , a cut surface of a grayish white solid mass was revealed , which invaded one half of the myometrium . the third was an irregular elevated mass - like lesion , measuring 2.5  1.3  1 cm in dimensions . the cut surface of this lesion showed a grayish white solid mass without definitive myometrial invasion . the histologic findings and immunohistochemical staining results of these tumors revealed a malignant mixed mllerian tumor , papillary serous carcinoma , and endometrial adenocarcinoma , respectively ( fig . only the serous carcinoma component revealed invasive growth , while the other two components were confined to the endometrium . pelvic and para - aortic lymph nodes showed metastasis of the papillary serous carcinoma component . biopsied tissue from the serosal lesion of the sigmoid colon showed seeding of papillary serous carcinoma . tumors with a combination of different histology are divided into two clinicopathologic groups , collision or composite tumors ( 9 ) . the collision tumor has more than two juxtapositioned masses and each mass displays a different histology . in a collision tumor , each mass has a distinct boundary and is separated by non - neoplastic stroma . in contrast , the intermingling of more than two different components in one tumor mass is designated as a composite tumor . the present case has three separate masses located at the fundus , anterior and posterior wall of the uterine corpus , with different histology and immunophenotype . collision tumors of two distinct components have already been reported . however , to the best of our knowledge , a collision tumor with three distinct components has never been reported . the clinicopathologic characteristics of the previously reported and present uterine collision tumors are summarized in table 2 . the mean age of diagnosis was 66.1 yr ( range , 47 - 85 yr ) . the most frequent histologic type was endometrial adenocarcinoma ( 10/21 , 47.6% ) , followed by homologous and heterologous sarcomas ( 4/21 , 19.0% ) , endometrial stromal sarcoma ( 3/21 , 14.2% ) , malignant mixed mllerian tumor ( 2/21 , 9.5% ) , small cell carcinoma ( 1/21 , 4.7% ) , and hepatoid carcinoma ( 1/21 , 4.7% ) . the patients had received total hysterectomy and bilaterial salpingooophorectomy with or without pelvic - paraaortic lymph node dissection . adjuvant chemotherapy and/or radiation therapy was performed on three patients ( case 6 , 7 , 10 ) . figo stage ranged from ib to iiic , and most patients had a tumor with an advanced stage . four patients died in 4 to 18 months ( mean , 8.2 months ) after initial diagnosis . the deceased patients had tumors with high figo stage , two patients with figo stage iiib and the others with figo stage iiic . on the other hand , two patients who had a relatively lower figo stage remained alive up to the last follow - up period . the patient ( case 7 ) with figo stage ib survived for 6.5 yr and the patient ( case 6 ) with figo stage iiia , survived for 1.5 yr . in contrast to previous cases , the present case presents a patient with a collision tumor of figo stage iiic , who remained disease - free for 8 yr after the initial diagnosis . the favorable prognosis of this case may be due to the multimodal treatment performed on the patient . although advanced metastatic diseases generally have a poor survival rate , aggressive surgeries and adjuvant therapies may increase such survival rates . on reviewing the previously reported cases , pathologic information on myoinvasive components was found in 8 cases . among these cases , 4 ( case 2 , 5 , 6 , 7 ) demonstrated invasion of only the sarcoma component into the myometrium , whereas the carcinoma component was confined to the endometrium . these cases had endometrioid adenocarcinomas as the carcinoma component , known to have a relatively favorable prognosis ( 10 ) . invasive and metastatic components of collision tumors are supposed to be dependent on their original biologic behavior . this explanation is supported by cases presenting high - grade carcinomas collided with malignant mixed mllerian tumors . high - grade carcinomas , such as serous ( case 10 ) and hepatoid carcinomas ( case 8) , display myomterial invasion , whereas malignant mixed mllerian tumors are confined to the endometrium . these pathologic findings suggest that each component of collision tumors occur coincidentally with no connection , and the biologic behavior depends on their own tumor characteristics . the preoperative diagnosis of collision tumor is difficult when these tumor components are closely located . in our case the possible explanation includes that one mass was dominantly larger than the other two , and all these tumors were arising in the endometrium and faced each other in uterine cavity . careful pathologic examination provides exact tumor stage for each tumor and histologic subtype , which can lead to predict correct clinical behavior .
a collision tumor is defined by the presence of two separate masses in one organ , which are pathologically distinct . 
 we described a 70-yr - old patient who complained of abnormal vaginal bleeding with a collision tumor of the uterine corpus . 
 the patient received total hysterectomy , bilateral salphingo - oophorectomy , bilateral pelvic - paraaortic lymphadenectomy , omentectomy , and intraperitoneal chemotherapy . 
 the uterine corpus revealed three separate masses , which were located at the fundus , anterior and posterior wall . 
 each tumor revealed three pathologically different components , which were malignant mixed mllerian tumor , papillary serous carcinoma , and endometrioid adenocarcinoma . among these components , 
 only the papillary serous carcinoma component invaded the underlying myometrium and metastasized to the regional lymph node . 
 adjuvant chemotherapy and radiation therapy were performed . 
 the patient is still alive and has been healthy for the last 8 yr . 
 we have reviewed previously reported cases of collision tumors which have occurred in the uterine corpus .