Management of Pseudoangiomatous Stromal Hyperplasia (PASH)
For a reproductive-age woman with biopsy-proven PASH showing concordant imaging findings, observation with routine screening is appropriate; surgical excision is reserved for lesions >3 cm, progressive growth, or radiologic-pathologic discordance.
Initial Diagnostic Approach
Core needle biopsy is sufficient to confirm PASH when imaging findings are concordant with a benign process 1, 2. The diagnosis does not require surgical excision to rule out occult malignancy, as no malignant or premalignant cells directly arising from PASH have been identified after surgical excision of core-biopsy-confirmed PASH 1.
Key Clinical Features to Document
- Age and hormonal status: PASH predominantly affects premenopausal and perimenopausal women, with hormonal responsiveness being a key feature 3, 4.
- Presentation pattern: 53% present with screening mammography abnormalities, while 44% present with palpable masses 3.
- Lesion size: Measure precisely, as size >3 cm influences management 1.
- Associated findings: 30% of patients have concurrent cancer or carcinoma in situ at or before PASH diagnosis, making thorough evaluation critical 2.
Imaging Characteristics
PASH has nonspecific imaging features that often mimic fibroadenomas 3, 5:
- Mammography: Typically shows a noncalcified, circumscribed mass or developing asymmetry 3, 5.
- Ultrasound: Usually appears as an oval, circumscribed, hypoechoic mass, sometimes with an echogenic rim 3, 5.
- MRI: Most commonly shows non-mass enhancement with progressive (Type 1) kinetics; high-signal slit-like spaces may be visible on T2-weighted images corresponding to pseudoangiomatous clefts 3, 5.
Management Algorithm Based on Core Biopsy Results
When Core Biopsy Confirms PASH (65% of cases) 1, 2
Observation is appropriate if:
- Radiologic-pathologic concordance is confirmed 5
- Lesion is ≤3 cm 1
- No suspicious radiologic features are present 2
Surveillance protocol:
- Diagnostic mammogram and/or ultrasound at 6 months 2
- Continue imaging every 6-12 months for 1-2 years 2
- Return to routine age-appropriate screening if stable 5
When Core Biopsy is Negative or Inconclusive (35% of cases) 2
Surgical excision is mandatory for:
- Radiologic-pathologic discordance 5
- Lesions >3 cm at presentation 1
- Progressive growth on surveillance imaging 1, 2
- Suspicious radiologic findings despite benign core biopsy 2
- Inconclusive biopsy results 2
Surgical Management When Indicated
Complete excision with clear margins is the treatment of choice for tumorous PASH 4. The prognosis is excellent with minimal recurrence risk after adequate surgical excision 4.
Post-Excision Follow-Up
- If final pathology confirms simple PASH: Return to routine age-appropriate screening 5
- Recurrence rates: 13% after excision versus 26% with observation alone 2
- Close surveillance remains necessary given the recurrence potential 2
Critical Pitfalls to Avoid
Radiologic-pathologic concordance assessment is essential because PASH is often an incidental finding adjacent to the targeted lesion at histopathology 5. Discordant cases require surgical excision or repeat core-needle biopsy 5.
Do not confuse PASH with angiosarcoma on pathology: PASH has pseudoangiomatous slit-like clefts lined by myofibroblasts (CD34+, progesterone receptor+), while angiosarcoma has true vascular spaces 4, 5. This distinction is critical and requires expert pathology review.
Screen for concurrent malignancy: Given the 30% rate of associated cancer or carcinoma in situ, complete bilateral breast imaging and thorough clinical examination are mandatory at diagnosis 2.
Monitor for progression factors: Lesion size, enlargement of palpable mass, and diagnosis other than PASH on core biopsy are associated with progression and warrant more aggressive management 1.