Fine needle aspiration cytology of mammary pseudoangiomatous stromal hyperplasia. A case report

Mammary mesenchymal and fibroepithelial lesions: An illustrated cytomorphologic update with differential diagnoses

The Uniform Approach to Breast Fine Needle Aspiration Biopsy was put forward by a learned group of breast physicians in 1997. This landmark manuscript focused predominantly on diagnosis and reporting of mammary epithelial lesions. Today, most American practitioners turn initially to core biopsy rather than aspiration biopsy for the first line diagnosis of solid breast lesions; however, recent efforts from the International Academy of Cytology have produced a system called the Standardized Reporting of Breast Fine Needle Aspiration Biopsy Cytology (colloquially labeled in 2017 as the "Yokohama System"), suggesting a new interest in breast fine needle aspiration (FNA), especially in resource limited settings or clinical practice settings with experienced breast cytopathologists. Fibroepithelial lesions of the breast comprise a heterogeneous group of biphasic tumors with epithelial and stromal elements. Mesenchymal lesions of the breast include a variety of neoplasms of fibroblastic, myofibroblastic, endothelial, neural, adipocytic, muscular, and osteo-cartilaginous derivations. The cytology of mesenchymal breast lesions is infrequently described in the literature and is mainly limited to case reports and small series. This illustrated review highlights the cytologic features of fibroepithelial and mesenchymal mammary proliferations and discusses differential diagnoses and histomorphologic correlates.

Pseudoangiomatous Stromal Hyperplasia of the Breast

Pseudoangiomatous stromal hyperplasia is a relatively common lesion of the breast. In general, it is less commonly found as a clinically palpable mass and is more commonly found as incidental microscopic foci. It is a benign proliferative, probably neoplastic, hormonally driven process of the mammary stromal myofibroblasts. The clinical, radiologic, and cytologic findings can resemble those of fibroadenoma. Histologically, it can be confused with low-grade angiosarcoma. The exact etiology of pseudoangiomatous stromal hyperplasia is still controversial, but a neoplastic process of the stromal myofibroblasts, with a hormonal stimulus in its development and progression, is the favored theory. Most lesions can be cured by complete surgical excision, and patients undergoing the excision have a good prognosis.

Rapidly growing nodular pseudoangiomatous stromal hyperplasia of the breast in an 18-year-old girl. Case report

Pseudoangiomatous stromal hyperplasia (PASH) of the breast is a rare benign proliferation of mesenchymal stromal cells with irregular slit-like formations resembling angiomatous structures. In the majority of cases this lesion is a focal microscopic finding in breast biopsies performed for benign or malignant diseases. It may present in a pure diffuse or nodular form. The exact etiology and pathogenesis of this tumor-like lesion is still unknown, but a proliferative response of myofibroblasts to hormonal stimuli has been postulated. A large 12 x 9 x 3.5 cm rapidly growing nodular form of PASH of the breast in an 18-year-old woman is here described with clinical and histological findings. A possible hormonal etiology was indicated by elevated progesterone (three-fold) and decreased estrogen serum levels. Different diagnostic lesions, such as giant fibroadenoma and low-grade angiosarcoma, are discussed. To the authors' knowledge this is only the fourth case of nodular PASH of the breast reported in the English literature.

Can hamartoma of the breast be distinguished from fibroadenoma using fine-needle aspiration cytology?

In an attempt to determine if it is possible to distinguish hamartoma of the breast from fibroadenoma using fine-needle aspiration cytology, we reviewed the cytological slides of 13 histopathologically confirmed cases of hamartoma of the breast and compared them with the cytological features of 13 histologically confirmed fibroadenomas. In each case, we studied the epithelial and stromal features. Cytologic characteristics were retrospectively evaluated in a semiquantitative manner. In conclusion, the finding of intact lobular units and a relative paucity of stroma may suggest the diagnosis of hamartoma.

Cytomorphology of Benign Breast Disease

Fine needle aspiration biopsy is a widely used technique for the initial diagnosis of mammary lesions. The majority of patients undergoing fine needle aspiration biopsy of a breast lesion will have a benign disease of the breast. This article provides a review of the cytomorphologic features in a variety of benign breast lesions,and discusses the commonly encountered differential diagnoses on aspiration biopsy. Topics discussed include inflammatory and reactive conditions, treatment-induced changes, pregnancy-related changes, benign proliferative lesions, and benign neoplasms of the breast.

Nodular pseudoangiomatous stromal hyperplasia of mammary stroma in a case showing rapid tumor growth

Pseudoangiomatous stromal hyperplasia (PASH) is an uncommon benign breast disease that presents as a localized breast mass. Breast tissue affected by PASH is characterized by a dense, collagenous proliferation of mammary stroma, forming interanastomosing capillary-like spaces. The importance of this benign lesion lies in distinguishing it from low grade angiosarcoma. We report a case of a 38-year-old woman who presented with a rapidly growing breast tumor. She visited our hospital with a complaint of a painless right breast mass. Physical examination revealed a 3.6 x 2.2 cm, oval, elastic-firm, well-defined and easily movable mass. Mammograms revealed no discrete mass or calcifications. Sonographic examination revealed a 3.5 x 2.5 x 2.2 cm, oval, well-defined and homogenous hypoechoic mass without a cyst. A fine-needle aspiration sample of the breast mass showed some clusters of epithelial cells with small papillary structures and many scattered stromal cells with naked nuclei. Based on these findings, a provisional diagnosis of fibroadenoma was made and the patient was followed up. One year after the first visit, the mass enlarged rapidly and a follow-up mammogram revealed an 8.2 x 5.5 cm circumscribed mass without calcifications. Given the history of rapid growth of the mass, tumor excision was performed. The excised tumor was well demarcated and had a smooth external surface. Histologic examination revealed normal breast ducts and lobules, and specific proliferative epithelial changes were not seen. The lobular and duct structure of the breast parenchyma were separated by an increased amount of stroma. The fibrous stroma contained numerous anastomosing slit-like spaces. Isolated spindle cells appeared intermittently at the margins of the spaces resembled endothelial cells. Immunohistochemical staining showed that endothelial cells lining true blood vessels were positive for Factor VIII-related antigen, but the spindle cells were negative for Factor VIII. Pseudoangiomatous stromal hyperplasia was diagnosed.

Aspiration biopsy of nodular pseudoangiomatous stromal hyperplasia of the breast: clinicopathologic correlates in 10 cases

Nodular pseudoangiomatous stromal hyperplasia (PASH) of the breast is rare and often indistinguishable from fibroadenoma, clinically and on aspiration biopsy smears. We report our observations in 10 patients with PASH, evaluated by fine-needle aspiration (FNA) biopsy and core biopsy. We retrospectively reviewed the clinical, radiographic, cytologic, and histologic findings in 10 cases of pure nodular PASH. Ten patients with a presumed clinical and radiologic diagnosis of fibroadenoma underwent aspiration biopsy. The aspiration smears were diagnosed as fibroadenoma (4 cases), cellular fibroadenoma (1 case), schwannoma versus neurofibroma (1 case), fibrocystic change (3 cases; 2 with atypia), and "not specific for a lesion" (1 case). A diagnosis of PASH was not suspected in any case. A discrepant or imprecise cytologic diagnosis and/or the presence of dissociated spindle or epithelial cells, or cellular stromal fragments prompted a surgical excision in 7 of 10 patients (70%). The remaining 3 patients exhibited cytologic features of fibroadenoma and were diagnosed as such; however, surgical excision was recommended. Three patients underwent a subsequent core biopsy, with a diagnosis of PASH being made in 1 patient. FNA biopsy could not discriminate PASH from fibroadenoma in 4 of 10 patients (40%) or suggest a diagnosis of PASH in any case. On retrospective review, the finding of plump, spindle-shaped mesenchymal cells may be a cytologic clue to suggest a diagnosis of PASH.

Mammary pseudoangiomatous stromal hyperplasia presenting as an axillary mass

Pseudoangiomatous stromal hyperplasia (PASH) of the breast is characterized by interanastomosing slit-like spaces lined with spindle-shaped cells in an abundant fibrous stroma. PASH is a relatively common incidental finding in the breast tissue removed for other reasons and rarely presents as a localized mass. The etiology of PASH is unknown, but hormonal factors are thought to be involved. Accessory breast tissue is subject to all pathologic changes found in the normal breast. We report a case of PASH that presented as a palpable axillary mass in a 43-year-old woman. To our knowledge, PASH has not previously been reported in the axillary accessory breast tissue. The spindle stromal cells in our patient showed immunophenotypic characteristics of myofibroblastic differentiation. Immunoreactivity for progesterone receptor was noted in the spindle cells. These findings support the hypothesis that endogenous hormones are involved in the development of PASH.

Pseudoangiomatous Stromal Hyperplasia of the Breast in Two Adolescent Females

The majority of breast lesions that present in adolescent girls are benign, with most being fibroadenomas. Rarely, a large and rapidly growing breast mass may be found to be the more recently described entity named pseudoangiomatous stromal hyperplasia (PASH). The pathogenesis of this lesion is attributed to hyperplasia of stromal myofibroblasts in response to hormonal stimuli. To date, PASH has rarely been described in adolescence. We describe the presentation of PASH in two adolescent patients. The first is a 12-year-old girl who found a mass in her left breast 3 months prior to presentation. An excision of an 11.5 x 10 x 3.5 cm lesion weighing 347 g was performed via breast-conserving incisions. The second patient is a 16-year-old girl who also had a rapidly enlarging left breast mass removed in a similar fashion. This mass measured 12 x 11 x 6 cm and weighed 460 g. Both tumors were noted to have a smooth capsule. Histologic appearance consisted of the typical features of PASH; fibrous stroma containing numerous anastomosing slit-like spaces; some compressed and others with discernible lumina. Both patients had complete excisions and have since not experienced recurrence. Each has had excellent cosmetic results with symmetrical breast development since their resection. Pseudoangiomatous stromal hyperplasia is a rare tumor that arises in the breast. These tumors may grow quickly and often are mistaken for fibroadenomas, phylloides tumor, or angiosarcoma. They must be resected with careful attention to resection around the capsule of the tumor with breast conservation as a goal. Long-term follow-up is necessary, as some have been reported to recur.

Nodular myofibroblastic stromal hyperplasia of the mammary gland as an accurate name for pseudoangiomatous stromal hyperplasia of the mammary gland

Pseudoangiomatous stromal hyperplasia (PASH) of the mammary gland is a well-known benign localized form of stromal overgrowth with probable hormonal etiology. We describe the histologic findings and immunohistochemistry of two cases. Two women, 16 and 58 years old, presented with a breast mass and underwent surgical excision. Grossly, they consisted of a well-circumscribed, rubbery tissue with a solid white-tan homogeneous cut surface. One of the cases showed focal cystic areas. Histologically the lesion showed a proliferation of the collagenous stroma with varying degrees of density, and hyalinization with many pseudovascular slit-like anastomosing spaces lined by spindle cells with scant cytoplasm and bland chromatin. The spindle cells lining the spaces were strongly reactive for vimentin and weakly reactive for CD34, actin, and desmin. They were negative for factor VIII, S-100, and pankeratin. In PASH, the "pseudoangiomatous" term describes a recognizable pattern but does not describe the tumor's histologic nature. We propose the name nodular myofibroblastic hyperplasia of the mammary stroma as a more accurate name.

Pseudoangiomatous stromal hyperplasia of the breast

Pseudoangiomatous stromal hyperplasia is a benign proliferative lesion of the mammary stroma that rarely presents as a localized mass. We describe the clinical, radiologic, cytologic, and histologic features of a case of pseudoangiomatous stromal hyperplasia that presented as a rapidly growing breast lesion in a 36-year-old woman.