Metastatic lobular carcinoma of the breast: patterns of spread in the chest, abdomen, and pelvis on CT.

Objective: We determined the pattern of spread of metastatic lobular carcinoma in the chest, abdomen, and pelvis on CT.

Materials And Methods: We identified 57 women (age range, 30-79 years; mean age, 57 years) with metastatic lobular carcinoma of the breast who underwent CT of the chest, abdomen, or pelvis between 1995 and 1998. Then two experienced oncology radiologists retrospectively reviewed 78 CT examinations of those patients to identify sites of metastatic disease and to identify complications caused by metastases.

Results: Metastases were identified in bone in 46 patients (81%), lymph nodes in 27 patients (47%), lung in 19 patients (33%), liver in 18 patients (32%), peritoneum in 17 patients (30%), colon in 15 patients (26%), pleura in 13 patients (23%), adnexa in 12 patients (21%), stomach in nine patients (16%), retroperitoneum in nine patients (16%), and small bowel in six patients (11%). Eighteen patients (32%) had gastrointestinal tract involvement that manifested as bowel wall thickening. Hydronephrosis was present in six patients (11%).

Conclusion: Although lobular carcinoma metastasized to common metastatic sites of infiltrating ductal carcinoma, lobular carcinoma frequently metastasized to unusual sites, including the gastrointestinal tract, peritoneum, and adnexa. Gastrointestinal tract involvement was as frequent as liver involvement, appearing as bowel wall thickening on CT. Hydronephrosis was a complication of metastatic lobular carcinoma.