Gastrointestinal (GI) metastasis from breast carcinoma is a rare occurrence. If metastasis occurs to the stomach/duodenum, it can present with symptoms of gastric outlet obstruction (GOO). Hence, it clinically mimics a variety of benign as well as malignant causes of GOO, including primary malignancy. GI metastasis from breast carcinoma occurs several years after the primary diagnosis and sometimes may be the first presenting symptom. If clinical records are not available, it may be misdiagnosed as poorly differentiated adenocarcinoma on biopsy. A high index of suspicion, subtle histologic clues, and appropriate immunohistochemistry helps in clinching the right diagnosis. Hereby, we report the case of a 55-year-old female who presented with metastasis to the duodenum 8 years post mastectomy which mimicked a primary ampullary/periampullary tumor.

Carcinoma ex pleomorphic adenoma (Ca ex PA) is a rare type of malignant salivary gland tumor. Myoepithelial carcinoma (MEC) as the malignant component in Ca ex PA is an even rarer occurrence. Preoperative pathological diagnosis of Ca ex PA often goes unnoticed in many cases as they may be clinically indolent and the malignant component may not be picked up on fine-needle aspiration cytology. However, features such as rapid growth, recurrent tumor, and pain point toward a malignant transformation. We present a case of a 40-year-old female who presented with a history of recurrent swelling over parotid region with cytological diagnosis of pleomorphic adenoma, which on excision was reported as Ca ex PA with MEC being the malignant constituent. Till date, few cases of MEC arising from PA have been reported. It presents as a diagnostic challenge to both clinicians and pathologists alike; prognosis is still not clear due to few number of cases and lack of follow-up in most of them.