a 62-year - old woman visited seoul national university bundang hospital due to a palpable mass in the left breast . the patient had a 15-year history of a painless mass of 3 cm in size which was increased over a period of six months . the patient had no family history of breast cancer or that of other medical conditions . core needle biopsy revealed a fibroepithelial lesion with a mild increase in the stromal cellularity . the patient was operated by simple mastectomy without lymph node dissection under a provisional diagnosis of benign phyllodes tumor . the surgical specimen was measured as 16.516.08.0 cm . grossly , the excised mass involved the nipple , measuring 10.09.59.0 cm , and it had a relatively ill - defined margin . the cut surface was whitish - yellow in color and it was lobulated with variably fleshy and firm areas ( fig . histologically , most of the tumor displayed typical characteristics of phyllodes tumor and these included tumor necrosis , the stroma with moderate - to - high cellularity , stromal overgrowth , moderate to severe nuclear atypia and increased mitotic activity ( 6 mitotic figures per 10 high power fields ) . these characteristics met the world health organization ( who ) criteria for a malignant phyllodes tumor ( fig . it was 6.0 cm in its greatest dimension and mainly showed a cribriform pattern of growth with well - formed tubular structures ( fig . 3a ) with low nuclear grade and low mitotic activity ( 1 mitotic figure per 10 high power fields ) . immunohistochemical staining of p63 and calponin demonstrated a lack of the myoepithelial cells within the area of invasive carcinoma ( fig . the tumor cells were immunoreactive for estrogen receptor ( 100% ) and progesterone receptor ( 95% ) and negative for human epidermal growth factor receptor 2 ( her-2/neu ) ( 1+/3 ) ( fig . in addition , they showed no immunoreactivity for cytokeratin 5/6 or epidermal growth factor receptor ( egfr ) ( fig . 3 g , h ) . however , stromal cells forming the malignant phyllodes tumor were immunoreactive for egfr . the patient received adjuvant fluorouracil , adriamycin , and cyclophosphamide chemotherapy for invasive cribriform carcinoma . phyllodes tumor is an uncommon biphasic breast tumor and it constitutes 1% of all breast tumors and 2 - 3% of fibroepithelial neoplasm.2 its histologic features include stromal hypercellularity and long clefts lined with several layers of epithelium . despite a lack of the standard grading system , phyllodes tumors are traditionally graded into benign , borderline , and malignant.1,2 according to three tiered grading subgroups of the who classification , a benign phyllodes tumor has modest degree of the stromal hypercellularity , little cellular pleomorphism , few mitotic figures , well circumscribed margin and uniform stromal distribution . on the other hand , a malignant phyllodes tumor shows marked stromal hypercellularity , marked cellular pleomorphism , numerous mitotic figures ( > 10 /10 high power fields ) , an infiltrative margin and stromal overgrowth . a phyllodes tumor which displays indeterminate features is categorized as a borderline malignancy.9 all phyllodes tumors may recur , but only the borderline and malignant phyllodes tumors metastasize.10 although the mitotic activity was modest ( 6/10 high power fields ) in our case , the tumor had stromal overgrowth , marked stromal hypercellularity and marked cellular pleomorphism . , only several cases of lobular carcinoma in situ,8 invasive lobular carcinoma,11 ductal carcinoma in situ,3,4,6,7,12 invasive ductal carcinoma,4,5,13 - 15 ductal and lobular carcinoma in situ16 and squamous carcinoma13,17 in phyllodes tumors have been reported . first described by page et al.18 in 1983 , invasive cribriform carcinoma is very rare and it is a unique type of the breast carcinoma . the invasive cribriform carcinoma is defined as the invasive carcinoma of breast showing more than 50% of cribriform pattern in the invasive component . the classical invasive cribriform carcinoma exclusively shows cribriform pattern or mainly cribriform pattern with a limited extent of tubular structure , while mixed one contains the areas of less well - differentiated invasive carcinoma . in our case , the invasive carcinoma component showed the characteristic features of invasive cribriform carcinoma , i.e. , a cribriform pattern of the growth of tumor cell nests and a few well - formed tubules with mild nuclear atypia . according to criteria of page et al.,18 our case can be diagnosed as a classical invasive cribriform carcinoma arising in a malignant phyllodes tumor . in our case , however , the cribriform nests were not aggregated . they were widely dispersed by the expanded stroma in some areas , thus making the differential diagnosis difficult . the cribriform pattern of tumor cells may also be present in ductal carcinoma in situ , adenoid cystic carcinoma and secretory carcinoma , all of which should also be considered in the differential diagnosis . adenoid cystic carcinoma also may exhibit cribriform patterns . and it has biphasic cellular components of the basaloid cells and ductal epithelial cells . besides , it is negative for estrogen receptor , progesterone receptor and her-2/neu.19 in the current case , there were no basaloid cells and basement membrane - like material in the lumen , both of which are the histopathologic findings of the adenoid cystic carcinoma , and there was a positive response to estrogen receptor and progesterone receptor by immunohistochemistry . secretory carcinoma has similar characteristics to lactating mammary glands and it is characterized by extensive secretions.20 however , these findings were not seen in our case . a majority of previous reports have shown that patients with carcinoma in phyllodes tumor achieve a good prognosis . to date , however , there are no methodical studies about or consensus on the prognosis of the above cases . of a total of 13 cases that have been reported up to present , nine patients survived with no evidence of disease progression during the follow - up period ranging from three months to nine years,3,4,6,8,11,12,14,15,17 and one patient died of the unrelated disease after a 9-year follow - up observation with no recurrence or metastasis.7 however , one patient experienced tumor recurrence . sugie et al.5 reported a case of 54-year - old woman who had invasive ductal carcinoma with squamous differentiation arising in malignant phyllodes tumor . two years and eight months postoperatively , this patient experienced lung and facial bone metastases of the sarcomatous component . approximately 22% of patients with malignant phyllodes tumors develop distant metastases where the lung and bone are affected most frequently and these patients eventually die of disease.9 in our case , it is difficult to predict the prognosis . the patient was followed up for short - term period and there were no recurrence or metastasis . in conclusion , our case is the first report of invasive cribriform carcinoma arising within malignant phyllodes tumor . although carcinoma arising in phyllodes tumor is rare , it should be considered in the diagnosis of phyllodes tumors with abnormal epithelial proliferation .
phyllodes tumor is an uncommon fibroepithelial neoplasm of the breast . and it is characterized by expanded stroma with increased cellularity and elongated epithelium - lined clefts . mammary carcinomas within phyllodes tumors have been rarely reported . to date , however , no reports have described the invasive cribriform carcinoma arising in malignant phyllodes tumor . here , we report a 62-year - old woman who presented with a large breast mass . 
 microscopically , the mass was a typical malignant phyllodes tumor showing well developed leaf - like architecture and stromal overgrowth with high cellularity and nuclear pleomorphism . in a portion of the tumor , 
 however , the epithelial component showed a cribriform pattern of proliferation in the absence of myoepithelial cells , suggestive of the invasive cribriform carcinoma . to our knowledge , this is rare and it is difficult to make a differential diagnosis of it . here , 
 we report our case with a review of literatures .