Pseudoangiomatous stromal hyperplasia (PASH) is a benign lesion of breast composed of prolifereted stromal myofibroblastic cells. It is named due to presence of slit-like spaces without endothelial layer mimicing vascular structures. Most of the lesions detected incidentally in breast tissues resected with other causes. Occasionally it may presented as palpable or radiologically detectable mass. It may confused with malignancy or phylloides tumor in clinically or radiologically if it grows rapidly. Differential diagnosis includes angiosarcomas and other sarcomas on histopathological examination. In this report a PASH lesion presented with differential diagnostic criteria, detected in a 34 year of woman with a breast mass growing markedly in 6 months duration.
