Traumatic breast pseudohernia presenting as a fungating mass during lactation: Multimodality imaging findings.

Pregnancy and lactation alter breast morphology, significantly complicating clinical and radiologic assessment. A fungating breast mass strongly raises suspicion of advanced malignancy. Isolated traumatic breast injuries causing parenchymal extrusion through the skin are extremely rare and are usually associated with fat necrosis. Although the literature reports instances of blunt traumatic mammary avulsion and fat necrosis forming deep cavities, direct herniation is rarely documented. A 20-year-old woman, 3 months postpartum, presented with a clinically suspicious 4-cm fungating left breast mass following direct blunt trauma to a faucet. High-resolution ultrasonography showed disruption of the skin and superficial fascial plane, with herniation of breast parenchyma through a 3.4-cm fascial defect, resulting in a 6.4-cm extramammary mass. No suspicious intra-mammary lesions or pathologically enlarged lymph nodes were detected. Noncontrast breast MRI confirmed a focal protrusion of breast tissue without features of invasive carcinoma or restricted diffusion. Given persistent clinical concern from the breast surgeon, a core needle biopsy was performed. Histopathology confirmed active lactational changes, an edematous stroma, and inflammatory infiltrates consistent with fat necrosis, with no evidence of epithelial atypia or malignancy. This case highlights an exceedingly rare post-traumatic breast pseudohernia that mimics an advanced fungating malignant process. Advanced multimodal imaging is critical for navigating complex diagnostic challenges during pregnancy and lactation. High-resolution ultrasound, the primary imaging modality, supported by noncontrast breast MRI, successfully differentiated this rare traumatic structural deformity from an invasive carcinoma, thereby preventing unnecessary radical surgical intervention.