Background: Pseudoangiomatous stromal hyperplasia (PASH) is a proliferative mesenchymal lesion of the breast histologically defined by dense collagenous stroma with spindle-shaped myofibroblasts. Characterization of patients with PASH has largely been limited to histologic and radiographic studies with small sample sizes due to the rarity of this benign condition. Furthermore, no existing studies of PASH have yet to consider race. Objectives: We undertook this study to identify subjects with PASH from electronic medical records (EMR) at the Vanderbilt University Medical Center (VUMC) and evaluate patient characteristics, including differences by race. Approach: We used natural language processing (NLP)-assisted searches to identify 283 subjects with pathology reports containing ‘PASH’ or ‘pseudoangiomatous stromal hyperplasia’. Results: We confirmed PASH by pathology report for 229 subjects (80.9%). The majority were Caucasian women, although 24 African Americans (10.5%) and 4 males (1.7%) with PASH were also identified. A total of 27 (11.8%) had a diagnosis of cancer as some point in their EMR, most frequently breast (74.1%) or thyroid (14.8%) cancer. The median age at PASH diagnosis was 45.4 years (range: 12.9-84.6) but this seemed lower among Asians (31.4 years). PASH was found more frequently in the left breast (54.8%) and was ascertained most often by core needle biopsy (76.0%), stereotactic needle biopsy (11.8%), or excision (7.0%). Among initially biopsied patients, 20 (9.9%) and 39 (19.3%) had subsequent biopsies and excisions, respectively. No significant differences in any of these characteristics by race were identified. Conclusions: This data confirms that PASH is not exclusive to Caucasians and suggests that patient characteristics do not differ by race. Analysis of additional characteristics and patient outcomes, with inclusion of EMR time, is currently underway.

Citation Format: George Bukenya, Demetra Hufnagel, Nneka Anyawu, Stephanie Kurita, Alicia Beeghly-Fadiel. Characteristics of patients with pseudoangiomatous stromal hyperplasia (PASH): A retrospective cohort study [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B118.