Pseudoangiomatous stromal hyperplasia (PASH) is a benign breast condition of collagen proliferation. In this article, four cases are presented in series to illustrate the varying clinical presentations of PASH at mammography and sonography, as well as the vastly differing age groups that can be affected. A literature review of the aetiology, pathology and management of PASH is included to provide a comprehensive but succinct overview of the condition, what it is and how to recognise and manage it.
Pseudoangiomatous stromal hyperplasia (PASH) is an uncommon and cryptic breast condition, which was first documented in 1986 when it presented in a patient as a palpable breast mass.
The findings in four different patients imaged at Union Hospital between April 2016 and March 2018 are presented in this report to demonstrate the differing ages and presentations of biopsy-proven PASH. The cases highlight the existence of PASH, its varied forms of presentation and the implications for further patient management.
Although uncommon, it is important to be aware of and recognise this condition in order to avoid submitting the patient to unnecessary surgery or follow-up examinations once it has been diagnosed.
Miss J, a 40-year-old asymptomatic woman, presented for routine screening. Her mammogram (
(a) Mediolateral and (b) craniocaudal mammography projections demonstrating clustered indeterminate calcifications in the right breast (arrows).
Arrows indicate the pseudovascular spaces.
Mrs K, a 50-year-old asymptomatic woman, was found to have probably benign nodules in her right breast at previous sonography 12 months earlier. At her annual follow-up mammogram and breast sonar, one of these lesions, located superiorly in the right breast, appeared to have increased very slightly in size and become less well defined on sonar (
(a–d) Normal appearing craniocaudal and mediolateral mammogram views and (e) right breast sonar image revealing a benign-appearing nodule.
Arrows indicate the pseudovascular spaces.
Miss M, a 14-year-old girl, presented for sonar assessment of a large, growing, palpable lump in her left breast. Corresponding to the lump, there was a 7 cm × 4 cm × 5.7 cm, slightly mixed, predominantly isoechoic, probably benign mass on sonar (
Longitudinal (a) and transverse (b) sonographic images of the predominantly isoechoic, palpable lump.
Immunohistochemical stains were as follows:
Estrogen receptor (ER) positive in the duct component and negative in the stromal component.
Progesterone receptor (PR) positive in the epithelial component and negative in the stromal component.
MNR116 positive in the epithelial component and negative in the stromal component.
Androgen receptor focal positive in the stromal component.
CD34 positive in the vascular element only.
Mrs Z, a 71-year-old diabetic woman, presented complaining of a palpable lump in the right breast. Her mammogram showed extremely dense tissue with a grade D pattern and increased density in both upper, outer quadrants (
(a–d) Craniocaudal and mediolateral mammogram with a grade D dense breast pattern and (e) sonar demonstrating an area of hypoechogeneity with posterior acoustic shadowing (arrow).
Arrows indicate the pseudovascular spaces.
In all cases, there was radiological and pathological concordance. Annual surveillance was advised for cases 1, 2 and 4. Case 3 required no radiological follow-up but was referred for surgical opinion to discuss the option of surgery in view of possible aesthetic problems because of the size and enlargement of the mass and the patient’s preference. However, the patient did not attend her surgical appointment.
Pseudoangiomatous stromal hyperplasia is a benign breast condition of collagen proliferation. The exact aetiology and pathogenesis are unknown, but hormonal factors are known to play a role in the development of PASH; it is more common in pre- and perimenopausal women.
In known cases of PASH, the lesion size was shown to change with menses, consistent with a hormone-related fluctuation.
Clinically, PASH usually presents as a mass, typically enlarging, sometimes rapidly.
Radiologically, the classic description of PASH is of a single, well-circumscribed, round or oval, mobile mass, resembling a fibroadenoma on mammogram and sonar.
On MRI, the findings of PASH are non-specific and range from an enhancing mass to clumped, non-mass-like enhancement, usually with benign kinetics.
However, as illustrated by the above cases, PASH may present with various other findings, none specific to the condition, and indeed, it is most commonly found as an incidental finding in a biopsy specimen, the biopsy having been done for another reason.
Breast tissue containing PASH exhibits stromal cell proliferation, that is, proliferation of collagen, with slit-like channels lined with myofibroblasts (spindle cells) resembling vascular channels.
The spindle cells are positive for Vimentin, CD34, BCL2, CD99 and
Radiological differential diagnosis depends on mode of presentation. As a benign-appearing mass, the main differentials are fibroadenoma and phyllodes.
The main pathological differential diagnoses are low-grade angiosarcoma and spindle cell containing entities such as phyllodes and desmoid tumours.
Pseudoangiomatous stromal hyperplasia is a benign condition. It is neither premalignant nor a risk factor for the development of carcinoma.
If the imaging findings are equivocal, a histological examination is mandatory for a definitive diagnosis.
A diagnosis of incidental PASH requires no active intervention or radiological follow-up. Pseudoangiomatous stromal hyperplasia is a BIRADS II condition.
Surgery may be performed for enlarging lesions, diffuse PASH with massive breast enlargement which is very rare
There is no established conservative treatment for PASH. It responds to tamoxifen; however, the effects may only be sustained with prolonged therapy. Long-term tamoxifen may not be ideal because of its side effects
Informed consent was obtained from all the patients for inclusion of their images and information in the study.
Any views expressed in this article are the author’s own and do not reflect the official position of DRS Inc. The author thanks Dr Blackburn for providing the images of the pathology slides.
The author declares that she has no personal or financial relationships that may have inappropriately influenced her in writing this article.