Tubulolobular
carcinoma (TLC) of the breast is a rare subtype of
breast carcinoma categorized by Fisher et al. (Hum Pathol 8:679-683, 1977) as a tubular variant of
lobular carcinoma.
E-cadherin is a transmembrane
glycoprotein, and complete loss of
E-cadherin expression has been observed in invasive
lobular carcinoma.
Ductal carcinoma retains at least some expression of
E-cadherin. Moreover, the adhesive function of
E-cadherin is dependent on the integrity of the
catenin components, which link
E-cadherin to the actin filaments. In order to achieve improved categorization of TLC, we decided to investigate both
E-cadherin and the
catenins in TLCs and invasive
lobular carcinomas. We reviewed all 1,430 cases of primary
breast carcinoma that were surgically resected at Saitama Medical Center, Saitama Medical School, and at Saitama Red Cross Hospital between 1990 and 2005. Among these, 16 cases of TLC were reported retrospectively. The results were compared with those of 20 cases of invasive
lobular carcinomas that were included as controls.
Tumor tissue was immunostained for
E-cadherin,
alpha-catenin, and
beta-catenin. The presence of immunoreactivity in the TLC was seen in 12 (75%) cases for
E-cadherin, in 8 (50%) cases for
alpha-catenin, and in 10 (62.5%) cases for
beta-catenin. However, plasma-membrane-associated staining for
E-cadherin,
alpha-catenin, and
beta-catenin was completely absent in invasive
lobular carcinomas. These results suggest the possibility that TLCs are not a variant of
lobular carcinoma, but rather
ductal carcinomas with a lobular growth pattern.