a 67-year - old post - menopausal woman visited the clinic due to vaginal bleeding .
levels of serum tumor markers , including carbohydrate antigen 125 and carbohydrate antigen 19 - 9 , were normal .
curettage of the endometrial lesion showed endometrioid adenocarcinoma , the international federation of gynecology and obstetrics ( figo ) g1 .
there was an ill - demarcated grayish mass , measuring 43.73.5 cm , on the anterior wall of the endometrium considered to be endometrial origin .
there was another well - demarcated heterogeneous white to yellowish partially hemorrhagic and fibrotic mass , measuring 654.4 cm , on the posterior wall of the myometrium .
the cut surface of the mass showed an ill - demarcated yellowish necrotic lesion , enclosed by a whitish fibrotic area .
1 ) . the endometrial lesion had the histologic appearance of endometrioid carcinoma , the same as the previous curettage ( fig .
the histologic findings of the myometrial mass were characterized by infiltration of spindle to ovoid cells into the surrounding leiomyoma .
frequent mitotic activity was encountered in up to 14/50 high - power fields ( hpf ) .
immunohistochemical staining was performed on the myometrial lesion for cd10 , caldesmon , desmin , -smooth muscle actin ( sma ) , human melanoma black 45 ( hmb-45 ) , melan - a , transcription factor e3 ( tfe3 ) , and ki-67 .
the infiltrating tumor cells were positive for sma , hmb-45 , and tfe3 with a low ki-67 index of about 5% , but they were negative for cd10 , caldesmon , and desmin ( fig .
pecomas , which have no known normal tissue counterpart , are unique in that they react immunohistochemically for both melanocytic and myoid markers .
reviewed 26 cases of pecomas of soft tissue and gynecologic origin . according to that report , all cases demonstrated expression of at least one of the melanocytic markers ( hmb-45 , melan - a , and microphthalmia transcription factor ) , and hmb-45 showed the highest rate of positivity at 92% .
they also showed positivity for myoid markers with sma ( 80% ) and desmin ( 36% ) .
our case demonstrated positivity for both hmb-45 and melan - a , and melanin pigments were observed in some cells . among the myoid markers , our case was positive for sma and negative for desmin and caldesmon .
the existing leiomyoma was positive for desmin and caldesmon , so the pecoma was clearly defined from the large preexisting leiomyoma at the peripheral portion of the bulky mass .
we reviewed all case series published in english available in pubmed that included more than three cases of pecoma in the female genital tract , for a total of 63 cases .
the results ( table 1 ) [ 6 - 8 ] show that all ( 100% ) of the tested cases showed positivity for hmb-45 , and 52.8% were positive for melan - a .
myoid markers including sma , caldesmon , and desmin were positive in 74.5% , 66.0% , and 94.4% of tested cases , respectively .
cd10 immunostaining was performed in 23 cases and showed positivity in six cases ( 26.1% ) .
these results confirm the diagnostic value of immunohistochemistry profiling in uterine pecoma , especially the use of melanocytic and myoid markers , due to their high rates of positivity .
the differential diagnosis of uterine pecoma includes uterine smooth muscle tumor , endometrial stromal tumor , gastrointestinal stromal tumor ( gist ) with secondary involvement of the uterus , and other sarcomas such as alveolar soft part sarcoma ( asps ) .
paraganglioma , metastatic melanoma / clear cell sarcoma of soft part , and rarely , carcinoma should also be considered in the differential diagnosis due to their epithelioid cytomorphology .
positivity enables a differential diagnosis of pecoma from uterine smooth muscle tumor , endometrial stromal sarcoma , and asps .
there was a report of late pulmonary and renal metastatic pecomas with initial misdiagnosis as uterine leiomyosarcomas .
cd10 , which usually shows diffuse and strong immunoreactivity in endometrial stromal tumors , may be helpful in the differential diagnosis because 25% of uterine pecomas are reported to be positive for cd10 .
the exclusion of gist from pecoma may be possible on the basis of cd34 staining , as well as c - kit positivity and melanocytic marker negativity in gists .
metastatic melanoma and/or clear cell sarcoma can be distinguished from pecoma by the strong s-100 protein immunoreactivity of the former and their muscle marker negativity .
tfe3 is a member of the mit family of transcription factors , and tfe3 gene fusions have been found in some neoplasms such as asps and a subset group of renal cell carcinoma .
the group harboring tfe3 gene fusion is reported to be more common in young patients , to be unrelated to tuberous sclerosis , to show alveolar architecture , and to have more epithelioid than spindle cell cytology and minimal immunoreactivity for myocytic markers .
because of the small number of cases , however , it is difficult to define these cases as a single distinct group showing specific clinical characteristics compared with conventional pecomas .
there was a report of a concomitant pecoma and an endometrioid carcinoma with synchronous / metastatic bilateral ovary carcinomas and uterine leiomyoma .
the case had a finding common to ours in that there was a well differentiated endometrial carcinoma involving a depth of more than half of the myometrium with a synchronous separate pecoma . in that case , however , the pathologic examination revealed benign features of pecoma and it presented as a subserosal mass , unlike our case , which presented as a protruding endometrial mass and showed malignant features .
criteria for malignancy of pecoma of the female genital tract are currently not clearly defined due to insufficient case studies . according to criteria that are currently accepted ,
pecomas are classified into three categories : benign , uncertain malignant potential , and malignant .
benign is defined to exhibit the following gross or histologic features : gross size < 5 cm , non - infiltrative growth , non - high - grade nuclear features , no necrosis or vascular invasion , and a mitotic rate < 1/50 hpf .
tumors of uncertain malignant potential are defined as corresponding to one or more of the following features : nuclear pleomorphism or multinucleated giant cells , or gross size > 5 cm regardless of cellular features . satisfying the malignant category refers to cases which show two or more of the following features : gross size > 5 cm , infiltrative growth , high - grade nuclear features , necrosis , vascular invasion , or a mitotic index 1/50 hpf .
according to the largest single series of pecomas of gynecologic origin , the current classification system was very specific and sensitive for the diagnosis of malignant pecoma in the gynecologic tract .
 perivascular epithelioid cell tumors ( pecomas ) refers to a family of mesenchymal neoplasms composed of angiomyolipomas , clear cell  sugar  tumors of the lung , and lymphangioleiomyomatoses . 
 these tumors have a distinctive and common component of perivascular epithelioid cells that show an association with blood vessel walls and immunohistochemically display myomelanocytic differentiation . 
 the unique neoplasms have been shown to have an expanded range through a variety of case reports , including visceral , intra - abdominal , soft tissue , and bone tumors . 
 the retroperitoneum , abdominopelvic region , and uterus have been reported to be the most common sites . 
 most pecomas follow a benign course . 
 however , reports of malignant pecomas are increasing . 
 many papers have described uterine pecomas , but to our knowledge , there have not yet been any reports of a malignant pecoma arising concomitant with another epithelial tumor and mesenchymal tumor . 
 we report herein the case of a 67-year - old woman who experienced a malignant uterine pecoma infiltrating a preexisting intramural leiomyoma with synchronous well differentiated endometrial carcinoma and multiple liver and lung metastases . 
CASE REPORT
DISCUSSION