a 43-year - old korean female ( gravida 2 , para 2 ) with a three - year history of a palpable abdominal mass was admitted to the gynecology outpatient department . a recent evaluation showed a marked increase in tumor size ( up to approximately 8.0 cm ) and the presence of abdominal pain . abdominopelvic computed tomography showed a large enhancing mass measuring 13.0 cm that encased the left adnexa , the uterus , and the left iliac vein ( fig . 1 ) . omental haziness and small seeding nodules suggested the possibility of seeding carcinomatosis peritonei . total abdominal hysterectomy and bilateral salpingo - oophorectomy were performed with removal of the parametrially extended tumor . grossly , the multinodular mass was dark red , congested and spongy with bulbous protuberances over the extrauterine surface and bilateral broad ligaments ( fig . contrary to the dark red color of the external surface , the cut surface showed a homogeneous , grayish tan - colored , multinodular , firm trabeculated appearance ( fig . microscopically , the excised mass was composed of variably sized multiple nodules , which were surrounded by perinoudular widened hydropic degeneration ( fig . the nodules consisted of fascicles of spindle cells with no cellular pleomorphism , mitotic activity , or coagulation necrosis ( fig . the mass encased the bilateral ovaries and salpinges , which were free from tumor invasion . immunostaining for cd34 highlighted the endothelial cells of the blood vessels surrounding the foci of the intravascular growth of the leiomyoma ( fig . the spindle cells were positive for muscle - specific actin ( ia4 , prediluted , dako , glostrup , denmark ) and desmin ( d33 , prediluted , dako ) . cdl , the least variant of benign uterine leiomyomas , is characterized by extrauterine bulbous expansile growth continuous to the intrauterine location of the mass , mimicking a grape - like appearance.1 - 3 due to its bizarre gross morphology ( including a large size , widespread invasive growth , etc . ) and status as a rarely encountered , unfamiliar variant , an intraoperative impression of malignant neoplasm , especially leiomyosarcoma , was initially suspected . however , uterine cdl can be distinguished from leiomyosarcoma in that the former has a consistency that is not soft but firm instead . in addition , macroscopic differential diagnoses , such as sarcomas ( e.g. leiomyosarcomas ) , can be easily excluded after microscopic observation.1,4 microscopic differential diagnoses included intravascular leiomyomatosis , disseminated peritoneal leiomyomatosis , and benign metastasizing leiomyoma . intravascular leiomyomatosis is characterized by a grossly visible vascular invasion of a histologically proven benign smooth muscle tumor.10 disseminated peritoneal leiomyomatosis shows numerous small ( usually less than 2 cm in size ) smooth muscle tumorlets spread across the peritoneum.11 benign metastasizing leiomyoma is a morphologically benign leiomyoma occurring at distant extrauterine sites , such as the lung or regional lymph nodes.12 the exact nature of cdl remains unclear . the exophytic dark red portion of the cdl may be caused by venous obstruction and congestion , and the endophytic intramyometrial portion with poorly defined borders may arise from the parent leiomyoma between the myometrium.2 ultrasonographic findings are not distinct from other conventional leiomyomas . magnetic resonance images of cdls show heterogeneous intensity with patchy isosignal nodules and stromal components with a high signal on t2-weighted images.5 the high signal intensity reflects perinodular hydropic degeneration.6 after reviewing the 42 previously reported cases of cdls ( including the present one ) , all the cases showed no recurrence or metastases during the follow - up period.1 clinically , most cases occur in women of reproductive age , ranging from 23 to 73 years ( mean , 44 years ) . grossly , cdls are composed of an exophytic subserosal mass and an intramural endophytic portion with continuity . the size of the reported cdls ranged from 4 to 41 cm ( mean , 14.2 cm ) . microscopically , the nodules are separated by a fibrovascular connective tissue with marked hydropic changes or congestion filled with numerous vascular tissues.2 the spindle cells show no cellular atypia , mitosis or coagulation necrosis with a dissecting growth pattern due to perinodular extensive hydropic changes.1,2 intravascular growth is rare , and only 9 cases ( 21.4% ) have been reported in the 42 published cases of cdls , which includes the present case.1,4,7 - 9 foci of intravascular luminal growth pattern may cause misdiagnosis of the condition as a malignancy when present . intravenous leiomyomatosis behaves in a benign fashion although vascular invasion may extend as far as the extrauterine pelvic veins , the inferior vena cava , and even up to the right side of the heart.10 similarly , cdls with intravascular luminal growth have been known to pursue a benign nature but with uncertain biological behavior.7 further accumulated cases will be required to establish the prognostic impact of intravascular luminal growth in these rare entities . to avoid misdiagnosis , especially in intraoperative frozen diagnosis , acknowledgment of this rare entity is important because it is known to have a benign biological behavior that mimics the gross morphology of a malignant tumor .
here , we report the case of a 43-year - old female who was diagnosed with a cotyledonoid dissecting leiomyoma ( cdl ) of the uterus . 
 cdl is a recently described and extremely rare variant of a benign leiomyoma that can grossly masquerade as a malignancy . 
 the 13-cm sized tumor was located primarily on the extrauterine surface as an intrauterine continuity , which showed dark red , congested , bulbous protuberances . 
 it was multinodular appearance , encasing the bilateral adnexae and the left iliac vein . 
 microscopically , the nodules were separated by extensive hydropic degeneration . 
 the nodules were composed of cigar - shaped spindle cells with no mitosis , cellular pleomorphism or coagulation necrosis . 
 they also showed an intravascular luminal growth pattern . 
 cdl with intravascular growth was diagnosed after excluding intravascular leiomyomatosis , disseminated peritoneal leiomyomatosis , and benign metastasizing leiomyoma . 
 the present case is the second reported case of cdl in korea . 
 recognition of this rare and bizarre , malignancy - mimicking leiomyoma is crucial to prevent inappropriate treatment .