The clinical behavior of mixed ductal/lobular carcinoma of the breast: a clinicopathologic analysis.

Background: To date, the clinical presentation and prognosis of mixed ductal/lobular mammary carcinomas has not been well studied, and little is known about the outcome of this entity. Thus, best management practices remain undetermined due to a dearth of knowledge on this topic.

Methods: In this paper, we present a clinicopathologic analysis of patients at our institution with this entity and compare them to age-matched controls with purely invasive ductal carcinoma (IDC) and historical data from patients with purely lobular carcinoma and also stain-available tumor specimens for E-cadherin. We have obtained 100 cases of ductal and 50 cases of mixed ductal/lobular breast carcinoma.

Results: Clinically, the behavior of mixed ductal/lobular tumors seemed to demonstrate some important differences from their ductal counterparts, particularly a lower rate of metastatic spread but with a much higher rate of second primary breast cancers.

Conclusions: Our data suggests that mixed ductal/lobular carcinomas are a distinct clinicopathologic entity incorporating some features of both lobular and ductal carcinomas and representing a pleomorphic variant of IDC.