A Rare Case of Duodenal Metastasis from Lobular Breast Cancer: From Diagnosis to Surgery.

Gastrointestinal tract breast cancer (BC) metastases represent a rare event and generally originate from the lobular subtype. Duodenal involvement was rarely described in previous case series. Abdominal symptoms are extremely unspecific and misleading. Diagnosis is challenging, and it consists of a few mandatory steps from radiological examinations to histological and immunohistochemical analyses. Here, we presented the clinical case of a 54-year-old postmenopausal woman who was hospitalized for vomiting and jaundice, presenting increased level of liver enzymes and minimal main bile duct and choledocus dilatation at abdominal ultrasonography. She underwent breast-conserving surgery and axillary lymph node dissection for stage IIIB lobular BC, 5 years before. Metastatic infiltration of the duodenal bulb originating from lobular BC was proven histologically, through fine-needle aspiration during endoscopic ultrasonography. Treatment was established after multidisciplinary team evaluation, based on the clinical status and prognosis of the patient. Pancreaticoduodenectomy was performed, and final histological examination confirmed the secondary localization of lobular BC, infiltrating the duodenal and gastric wall, pancreas parenchyma, and surrounding tissues. No metastatic lymph nodes were found. After surgery, the patient underwent first line of adjuvant systemic treatment with fulvestrant and ribociclib. After a follow-up of 21 months, the patient was in good clinical condition, without signs of locoregional or distant recurrence. This report stressed on the importance of a tailored therapeutic approach. Although systemic therapy generally represents the preferred option, surgery should not be excluded if an oncological radical resection can be performed achieving acceptable locoregional disease control.