Phyllodes tumour and stromal sarcoma of the breast: an ultrastructural comparison

Malignant Phyllodes Tumor of the Breast

Phyllodes tumors of the breast are rare lesions that historically have been presumed to be related to fibroadenomata, largely by virtue of the entities' histologic similarities. We report four cases of malignant phyllodes tumors (cystosarcoma phyllodes) of the breast, three showing liposarcomatous differentiation and one showing chondrosarcomatous and osteosarcomatous differentiation, each of which had demonstrable histologic continuity with benign fibroadenomata; one patient had a prior and concurrent history of multiple bilateral fibroadenomata. We postulate that fibroadenomata and phyllodes tumors (benign, borderline, and malignant) may constitute a spectrum of one stromal disease analogous to mammary epithelial hyperplasia, atypical hyperplasia, in situ, and invasive carcinoma. Int J Surg Pathol 3(1):17-22, 1995

Phyllodes tumor of borderline malignancy: seven year follow up with immunohistochemical study

The patient was 80 years old when she initially presented with a left breast mass. Originally, a needle biopsy showed benign stromal and ductal cells. Five years later, the breast mass increased in size and a core needle biopsy showed a biphasic intraductal papillomatous tumor with cellular stroma. Eighteen months later, another biopsy was taken from the breast mass, revealing a well-developed phyllodes tumor (PT) of borderline malignancy. One month later, a simple mastectomy was performed for this 87-year-old woman. Histolopathologic and immunohistochemical studies, including estrogen and progesterone receptors, Ki-67 and p53, performed on tissues from the different biopsy specimens confirmed the progressive transition of the tumor in a 7 year period. An increase in mitotic activity was noted in the later samples. Similarly, percentages of p53- and Ki-67-positive cells were much higher in the stromal and ductal cells of the later samples compared to the original specimen. These findings support the notion that Ki-67 and p53 immunohistochemical staining may be used as simple and practical markers for the evaluation of the malignant potential of PT.

Periductal stromal tumor: a rare lesion with low-grade sarcomatous behavior

Biphasic breast tumors with benign ductal elements and a sarcomatous stroma lacking a phyllodes architecture are a source of diagnostic problems, particularly because of the lack of an appropriate designation. At the Armed Forces Institute of Pathology, we have used the term "periductal stromal sarcoma" to distinguish these from phyllodes tumors. All cases coded as periductal stromal sarcoma or PDSH were retrieved from the files of the Armed Forces Institute of Pathology. Cases that fulfilled the following criteria were included in this study. The histologic features of periductal stromal sarcoma were defined as 1) a predominantly spindle cell stromal proliferation of variable cellularity and atypia around open tubules and ducts devoid of a phyllodes pattern, 2) one or more often multiple nodules separated by adipose tissue, 3) stromal mitotic activity of >/=3/10 high power fields, and 4) stromal infiltration into surrounding breast tissue. Criteria for periductal stromal hyperplasia included 1) nodular, bland stroma growing as cuffs around normal or altered ducts, 2) no to minimal atypia, and 3) at most 0-2 stromal mitotic figures per 10 high power fields. Immunohistochemistry was used to further characterize these neoplasms. Of the cases retrieved, 20 qualified as periductal stromal sarcoma and seven as periductal stromal hyperplasia. Patients with periductal stromal sarcoma ranged in age from 37 to 89 years (mean 55.3 years). The tumors measured 0.2-6.0 cm (mean 2.97 cm). Eighteen patients had excisional biopsies and two had partial mastectomies. Overall follow-up time ranged from 1 to 72 months (mean 25.3 months) with two patients (10%) showing recurrence or probable metastasis. The neoplastic cells of periductal stromal sarcoma were at least focally immunoreactive for CD34 (13 of 15), CD117 (6 of 15), less reactive for actin (HHF35, 2 of 15), and negative for estrogen and progesterone receptors. Periductal stromal sarcoma is a useful descriptive designation for generally low-grade biphasic tumors with sarcomatous stroma that do not have features of a phyllodes tumor. The development of focal phyllodes pattern in the recurrent tumor as well as development of a specific soft tissue sarcoma in one of the above cases suggest that some and possibly all periductal stromal sarcoma may evolve into a phyllodes tumor with time. Given the presence of infiltrative margins, excision with a rim of uninvolved tissue is required.

Rare case of biphasic tumor of the breast with prominent CD34-positive spindle cells

We report an unusual case of biphasic tumor of the breast with prominent CD34-positive spindle cells. A 53-year-old woman presented with a mass in her right breast. Following an incisional biopsy, a partial mastectomy was done. Histologically, the tumor was a biphasic variant of a malignant spindle cell tumor of the breast. The lack of a leaf-like structure, together with the apparent myoid features of the spindle-shaped tumor cells, made it difficult to distinguish from malignant phyllodes tumor and from myoepithelial carcinoma. Immunohistochemistry revealed the spindle-shaped tumor cells to be myofibroblastic, but not myoepithelial in nature, ultimately categorizing this tumor as a malignant phyllodes tumor with prominent myofibroblastic differentiation.

Phyllodes tumor of the breast. An immunohistochemical study of 28 cases with special attention to the role of myofibroblasts

The presence of myofibroblasts in the stroma of Phyllodes tumor of the breast has been documented in single cases by means of electron microscopy and immunohistochemistry. In this study, we re-evaluate the immunophenotype exhibited by 28 Phyllodes tumors (14 benign, 6 borderline and 8 malignant) in order to state the relevance of myofibroblasts as active stromal elements in these tumors. Vimentin showed positive immunostaining in the stroma of all the cases (100%), muscle-specific actin in 21 (75%), and desmin in 7 (25%). By contrast, stromal cells were uniformly negative for S-100 protein, keratins (AE1/AE3 and CAM 5.2), and epithelial membrane antigen (EMA). The epithelial component showed the typical two-layered arrangement of ducts in every case. Myoepithelial (outer) cells immunostained with muscle-specific actin and S-100 protein, and in some cases with EMA and keratins, whereas the epithelial (inner) layer did so with keratins and EMA. To conclude, we have found a prominent myofibroblastic differentiation in stromal cells of many of such tumors. Our results also prove that no differences in intensity or distribution of such actin-positive stromal cells are seen between benign, borderline or malignant counterparts.

Primary breast sarcoma: a review of 33 cases with immunohistochemistry and prognostic factors

The clinical and pathological features of 33 previously untreated patients with primary breast sarcoma were retrospectively analysed to evaluate the prognostic significance of histologic variables on survival. The series comprised 17 cystosarcomas phyllodes and 16 stromal sarcomas (excluding angiosarcomas). All tumors were reviewed and classified in similar fashion to extramammary soft tissue sarcomas. In addition, immunohistochemical studies were performed on paraffin sections with a panel of several antibodies directed against cytoskeletal filaments and cellular enzymes; five cases were also examined by electron microscopy. Most tumors were malignant fibrous histiocytoma (21 cases) and fibrosarcoma (6 cases) types. Surgery was the main therapy. Metastasis-free survival rate was significantly correlated only with histological grade, consisting of tumor differentiation, tumor necrosis, and mitotic activity. Courses and survivals of the cystosarcoma and stromal groups were identical, questioning the clinical value of this pathologic distinction. All local recurrence, metastasis, or death occurred within 30 months, though follow-up was much longer. Immunohistochemistry was disappointing for identification of specific histologic sub-types.

A human breast stromal sarcoma cell line with features of malignant cystosarcoma phyllodes

A cell line was established from a portion of a 25-cm stromal sarcoma of the left breast of a 65-year-old woman. The clinical course was rapid with tumor recurrence on the chest wall less than 1 month after mastectomy. Other cutaneous and abdominal metastases occurred shortly thereafter, and death followed within 3 months despite chemotherapy. The cultured cells, designated RW-972, produced large amounts of acid mucopolysaccharides (hyaluronic acid) and mimicked the aggressive growth characteristics seen in the patient. After injection into nude mice, the tumor grew rapidly and occasionally produced metastases. This unique cell line, RW-972, presumably derived from the stromal component of a human malignant cystosarcoma phyllodes, might be useful in studies of experimental therapy of this rare tumor type and of lobular stromal cells of breast. It may also be used to investigate hyaluronic acid production by tumor cells.

Primary spindle-cell sarcomas of the breast: diagnosis by fine-needle aspiration

Primary breast sarcomas (excluding cytosarcoma phyllodes and its sarcomatous recurrences) are rare neoplasms. Few have been described in the aspiration cytology literature. We report the cytologic features of two cases of stromal sarcoma (both with the pattern of malignant fibrous histiocytoma) and two cases of angiosarcoma. The dominant cytologic features included individual atypical spindle cells and fragments of collagenous stroma. Tumor giant cells were present in one stromal sarcoma. Features of possible significance in the diagnosis of angiosarcoma include obvious vessel formation by atypical spindle cells, bridging of adjacent tumor fragments by spindle cells, and microacinar structures lined by atypical spindle cells. The differential diagnostic considerations in spindle-cell breast aspirations are discussed.

Morphological and biological characteristics of mammary tumours induced by the direct application of DMBA powder to rat mammary glands

Mammary tumours were induced by the direct dusting of 1 mg, 7,12-dimethylbenz(a)anthracene (DMBA) powder onto the mammary gland of both 30-day-old female and male Sprague-Dawley rats, and the tumours were examined histologically. Mammary tumours developed in 43/43 (100%) of the females 11 to 20 weeks after DMBA dusting and 16/23 (70%) of the males 18 to 28 weeks after dusting, while non-mammary spindle cell sarcomas occurred in 5/23 (22%) of the males 15 to 24 weeks after dusting. A variety of benign and malignant mammary tumours of epithelial and/or mesenchymal origin were induced, which are comparable to human mammary tumours. Different histological patterns were observed in different areas of the same tumours. Ovariectomy revealed hormone (ovary)-dependency in 10/17 (59%) of the tumours, revealing regressing epithelial and proliferating mesenchymal tumour elements on histological examination.

Stromal proliferations of the breast: an ultrastructural and immunohistochemical evaluation of cystosarcoma phyllodes, juvenile fibroadenoma, and fibroadenoma

The stromal cells of three cystosarcoma phyllodes, five typical fibroadenomas, and one juvenile fibroadenoma were studied by light and electron microscopy. Immunohistochemical staining for the S-100 protein also was performed on tissues from each of the three categories. On ultrastructural examination, cells comprising the three varieties of lesions were similar. Cells with fibroblastic features predominated in all cases. Myoid differentiation was present in two cases, one of cystosarcoma and one of fibroadenoma. Junctional complexes were present in the cystosarcomas but not in the fibroadenomas. Basal lamina was focally present around stromal cells in the cystosarcoma phyllodes but was not evident around cells of the typical fibroadenomas or the juvenile fibroadenoma. Stromal cells of the fibroadenomas and the cystosarcoma phyllodes did not stain for S-100 protein. The results support the hypothesis that the proliferating cells in all three tumor categories are similar and have features of fibroblasts. The lack of staining for S-100 protein would suggest an origin different from the myoepithelia. The latter conclusion, however, must be interpreted with a degree of reservation as we have shown that not all myoepithelial cells stain with certain monoclonal antibodies directed against the alpha and beta chain of S-100 protein.