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rarely , it shows unusual growth patterns with associated extrauterine smooth muscle deposits that seem to be derived from a benign uterine leiomyoma ( benign metastasizing leiomyoma , bml ) .
hendrickson and kempson   defined bml as a muscle tumor in association with one or more smooth muscle tumors of the uterus and without evidence of any extrauterine primary site .
pulmonary metastases are usually detected by chest radiographs , years after hysterectomy . except for lung , the extrauterine sites that these tumors can localize to are skin , pelvis , abdomen , muscle , greater omentum , inferior vena cava , right atrium , brain and bones .
however , multiple metastases to lymph nodes in bml are rare and studies about prognosis and treatment of bml with multiple lymph node metastasis are few . here
a 34-year - old women with no medical history ( parity 1 - 0 - 0 - 1 ; normal spontaneous vaginal delivery at 2001 , never a smoker ) received an abdominal myomectomy for a palpable 8 cm abdominal mass with suspicion of leiomyoma by ultrasonography at a local clinic in july 2008 . on pathology
, it was found to be suspicious of cellular myoma or a smooth muscle tumor with uncertain malignant potential .
she was diagnosed as having a mitotically active leiomyoma and malignant potential . due a suspicion of multiple lymph node metastases on pelvis computed tomography ( ct ) 1 year after the operation , she was transferred to the samsung medical center ( october 2009 ) for further work up .
on pelvis ct , there was enlargement of multiple lymph nodes around the iliac chain and aorta .
an original pathology slide review ( fig . 1 ) and positron emission tomogarphy ( pet)-ct were done . according to the original slide review , it was a benign leiomyoma with a mitotic count < 5/10 high - power fields ( hpf ) , little cytological atypia and no tumor cell necrosis .
additional immunostaining indicated that smooth muscle actin and desmin were positive and cd10 was negative in the tumor cells .
tumor markers ( ta-4 , cancer antigen [ ca]-125 , ca-19 - 9 , carcinoembryonic antigen ) marked all normal .
abnormal fluorodeoxyglucose uptakes with the suspicion of paraaortic , aortocaval , precaval , external iliac lymph node and uterine body metastases were found on pet - ct .
incidentally , a 9 mm ground - glass opacity lesion at the right apical lung showed faint fdg uptake .
an additional chest ct also revealed it to be a primary lung cancer . in december 2009 extensive debulking surgery including total abdominal hysterectomy ,
bilateral salpingo - oophorectomy , pelvic and paraaortic lymph node dissection to the level of the left renal vein , and gonadal lymph node dissection were done .
grossly , there were no definite mass - forming lesions in the uterus , and all the lymph nodes stated above were palpable and enlarged to about 2 to 3 cm in size .
pathology for an ill - defined residual intrauterine lesion was also a benign leiomyoma with mitosis < 5/10 hpf , little cytological atypia and no tumor necrosis .
metastases to meso - ovarium / salpinx , pelvic lymph node , inferior mesenteric artery lymph node , para - aortic lymph node ( fig .
2 ) , gonadal vein and to the parametrium were confirmed on the final pathology report .
metastatic lesions were also reported to have similar histology with the original mass with a mitotic count < 2/10 hpf , little cytological atypism and no necrosis .
clinicopathologically , bml was selected as a final diagnosis with discussion with our pathologists ( cos and gha ) .
video - assisted thoracoscopic surgery right upper lobectomy with mediastinal lymph node dissection for solitary lung nodule was also done ( january 2010 ) . on tumor - node - metastases staging ,
the patient was pt1an0m0 ( stage 1b ) and it was consistent with a well - differentiated adenocarcinoma .
she started taking an aromatase inhibitor ( letrozole 2.5 mg daily , femara , novartis , basel , switzerland ) .
in the 4 month follow - up of our patient , she had no clinical , biochemical or radiological evidence of recurrence disease or distant metastases .
however , long - term follow - up is required for assessment of disease recurrence and distant metastases .
it is considered to be benign histologically , but it occasionally metastasizes to distant sites such as lung , heart , inferior vena cava , retroperitoneal lymph nodes , muscles , and the bone ( clinically malignant ) .
bml is usually characterized by uterine leiomyoma in young adulthood , with pulmonary metastasis occurring in the premenopausal period .
kayser et al .   reported that the mean interval between hysterectomy and the development of lung lesions was 24.9 years .
primary lung tumor in this case was incidentally detected on an imaging study , but since bml is known have metastases to lung most frequently , it is necessary to make a precise lung assessment during clinical follow up .
however , multiple pelvic and paraaortic lymph node metastases such as were present in this case are quite rare . here , the authors report this rare case . for an extrauterine lesion
pathologic and immunohistochemical studies to exclude other neoplasms are essential , especially when the metastatic site is uncommon .
previously reported cases of bml have included low - grade endometrial stromal sarcoma , which may play a significant role in the metastasis of benign uterine tumors .
however some research using genetic analyses showed bml to be clonally derived from benign - appearing uterine leiomyomas .
reported treatment modalities include careful observation , surgical resection , hysterectomy and bilateral oophorectomy , progestins , aromatase inhibitor , and medical castration using luteinizing hormone - releasing hormone analogues .
a radical surgical resection , if possible , has been advocated as the primary treatment .
the rationale for the use of hormonal therapy is based on the presence of estrogen and progesterone receptors in both the primary tumor as well as in the metastatic tumors
. clinical evidence of a hormonal influence was supported by the fact that the pulmonary nodules diminish in size following menopause , during pregnancy and after the withdrawal of hormonal contraception .
depending on the locations of the metastases and the hormone receptor status , we believe that treatment should be individualized for each patient . long - term close surveillance is required in a bml patient for early detection of disease recurrence or distant metastases . because of the limited therapeutic options , new drugs or new therapeutic modalities should be considered . in the future , studies with long - term follow - up may be helpful for their implication in clinical practice .
this is a case report about benign metastasizing leiomyoma with multiple lymph node metastasis . 
 a 34-year - old woman received an abdominal myomectomy for a suspicious leiomyoma . on the pathology report , 
 atypical leiomyoma was suspected . due to the suspicion of multiple lymph node metastasis on pelvis computed tomography ( ct ) 
 1 year after the operation , she was transferred to the samsung medical center on october , 2009 for further work up . according to original slide review 
 , it was determined to be a benign leiomyoma with a mitotic count < 5/10 high - power fields , little cytological atypia and no tumor cell necrosis . 
 additional immunostaining was done . 
 multiple lymph node metastasis and a small lung nodule were identified on positron emission tomogarphy - ct and chest ct . 
 extensive debulking surgery and diagnostic video - assisted thoracoscopic surgery ( vats ) wedge resection were subsequently done . 
 metastatic lesions were reported to have a histology similar to that of the original mass . 
 vats right upper lobectomy with mediastinal lymph node dissection was performed because of the pathology result of vats ( adenocarcinoma ) . 
 she started taking an aromatase inhibitor ( letrozole ) and there was no evidence of recurrence of disease on an imaging study and no post - operative complications until recently .