D. R. Layon1, A. D. Brooks2 1Drexel University College Of Medicine,Philadelphia, Pa, USA 2University Of Pennsylvania,Endocrine And Oncologic Surgery,Philadelphia, PA, USA
Introduction: Pseudoangiomatous stromal hyperplasia (PASH) is a benign breast lesion of mesenchymal origin for which the optimal treatment strategy is unclear. We performed a systematic review of the literature in order to determine if excision is necessary for managing PASH found on a biopsy.
Methods: Keyword searches for “pseudoangiomatous stromal hyperplasia” and “pseudoangiomatous hyperplasia of the mammary stroma” were queried in PubMed. Exclusion criteria were: articles not about relevant pathology, extra-mammary lesions, and inability to extract PASH data from mixed patient cohorts. Eligible articles were reviewed for patient demographics and study characteristics. We determined whether each reported cancer was incidentally or directly related to the PASH lesion. Incidental malignancies were: detected independently, temporally or spatially separate from the PASH lesions, or contained only microscopic foci of PASH. Malignancies were classified as directly related if located within PASH lesions.
Results: The search returned 122 results; 6 studies were obtained from other sources for a total of 128 studies. 18 studies were excluded. Eligible articles included: 51 case studies, 41 case series 17 review articles, and 1 textbook. The articles had a population of 1,508 individuals. 104 were male, 1,394 were female and 10 were not reported. 73% of PASH cases were managed via excision, 10% by observation, 1% by mastectomy, 0.79% by other methods (incisional biopsy, mammoplasty, or removal via core needle or vacuum-assisted biopsy), and 14% of cases had no reported management. There were 91 cases of malignant or pre-malignant lesions reported in the PASH literature (Table 1): invasive or noninvasive lesions, subtype not specified (48 cases), invasive ductal carcinoma (14), ductal carcinoma in-situ (DCIS, 16), Non-Hodgkins Lymphoma (3), invasive micro papillary carcinoma (1), invasive adenocarcinoma (5), and myofibroblastic sarcoma (4). Of the 91 cases, 34 were temporally separate, 21 spatially separate, 22 were identified independently of PASH, 8 had only microscopic foci of PASH and 5 were unable to be classified. The other 5 malignancies appear to be four cases of primary myofibroblastic sarcomas arising from PASH tumors and a single case of DCIS found within a PASH tumor. Thus, we estimate the incidence of malignant transformation of PASH lesions at 5/1508 or 0.3%.
Conclusion: Although most PASH lesions in the literature were treated by excision, the reported incidence of malignant transformation of PASH lesions is 0.3%. Based on the low incidence of malignancies arising from PASH lesions we conclude that the diagnosis of PASH alone, in the absence of other indications, does not require surgical intervention.
