BACKGROUND: Pseudoangiomatous stromal hyperplasia (PASH) is an uncommon benign breast lesion.

CASE REPORT: PASH is reported in a young female in treatment for neurological diseases with multi-drug therapy (clonazepam, valproate and risperidone). Her menstrual cycles are irregular, and she reached menarche very late.

CONCLUSIONS: The higher PASH prevalence in premenopausal woman (the majority of whom are actively taking oral contraceptive pills), in 24% to 47% of men with gynecomastia and during pregnancy supports a hormonal etiology; the interaction between clonazepam, valproate, risperidone and progesterone could increase the level of progesterone that could stimulate PASH growth.

Keywords: Breast Diseases, Breast Neoplasms, Drug Therapy, Combination, Mastectomy, Segmental, Angiomatosis, Biopsy, Large-Core Needle, Breast, Drug Interactions, Hyperplasia, Progesterone, Stromal Cells