Tubulolobular
carcinoma is a type of mammary
carcinoma that displays an admixture of invasive tubules and lobular-like cells. Previous reports have shown it to share clinical similarities to
lobular carcinoma, whereas more recent studies have shown it to be
E-cadherin positive. The aim of the current study was to further explore the immunophenotype of tubulolobular
carcinoma, and to document its natural behavior. Nineteen cases of tubulolobular
carcinoma and 10 cases each of tubular and
lobular carcinoma were retrieved for comparison analysis. Immunohistochemistry was performed with
antibodies against
estrogen receptor,
progesterone receptor, HER2/neu, 34betaE12,
E-cadherin, and the
catenins. Twenty-five percent of patients with tubulolobular
carcinoma presented with greater than stage I disease, compared to 0 and 60% of patients with tubular and
lobular carcinoma, respectively. Two patients with tubulolobular
carcinoma had
tumor recurrence, one of whom also developed
metastasis. The majority of all
carcinomas were
estrogen and
progesterone receptor positive.
E-cadherin displayed membranous staining in all tubular and tubulolobular
carcinomas, and was negative in all
lobular carcinomas. Half of each
carcinoma subtype displayed granular cytoplasmic 34betaE12 immunoreactivity.
alpha-Catenin exhibited partial or complete membranous staining in all tubulolobular and
tubular carcinomas, and was negative in all
lobular carcinomas.
beta-Catenin displayed membranous staining in tubulolobular and
tubular carcinomas, whereas all
lobular carcinomas had coarse cytoplasmic immunoreactivity. p120 and
gamma-catenin displayed membranous staining in 100% of tubulolobular and
tubular carcinomas and cytoplasmic staining in 100% of
lobular carcinomas. Tubulolobular
carcinoma of the breast is thus a distinct type of mammary
carcinoma that displays both tubular and lobular patterns histologically but displays the membranous
E-cadherin/
catenin complex characteristic of the ductal immunophenotype. Tubulolobular
carcinoma appears to be more aggressive than
tubular carcinoma, as 16% of patients had
lymph node metastases, although all were alive at a mean follow-up of 40 months.