Tubulolobular Carcinoma of the Breast

Abstract

Tubulolobular carcinoma (TLC) is a rare subtype of mammary carcinoma that has eluded precise classification, exhibiting features of both ductal and lobular differentiation. The clinicopathologic features of 27 cases of TLC were analyzed by both hematoxylin and eosin and immunohistochemical stains for E-cadherin and 34betaE12 (high molecular weight cytokeratin). Five cases of both pure tubular and classic lobular carcinoma were included as controls. Patients with TLC ranged in age from 43 to 79 years (median, 60 years). Tumor characteristics were as follows: size, 0.5 cm to 2.5 cm (median, 1.4 cm); bilaterality, 1 of 27 (4%); and multifocality, 5 of 27 (19%). Twenty-two of the 27 cases (81%) contained an in situ component: 8 (36%) lobular (LIN); 4 (18%) ductal (DIN); and 10 (46%) mixed. All 27 cases were intensely positive (3+) for E-cadherin, a feature of ductal differentiation, while 25 of 27 (93%) cases showed variable positivity for 34betaE12 (1 to 3+), a feature far more common in tumors with lobular differentiation. Clinical follow-up was available on 25 of 27 (93%) patients. Three of 24 (13%) patients developed axillary lymph node metastases and 1 of 25 (4%) patients developed a local recurrence over a follow-up period of 2 to 91 months (median, 39 months). In conclusion, TLCs are a distinct subtype of mammary carcinoma with overlapping morphologic features that are mirrored by a hybrid immunohistochemical profile. The uniform 3+ expression of E-cadherin in TLC supports the ductal differentiation of these tumors, despite a dominant lobular growth pattern. The prognosis of these tumors appears to be excellent, especially in those cases that are unilateral and less than 2 cm in size.

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

“…Of the available blocks, only one case did not stain for E-cadherin and may truly represent a lobular carcinoma. Wheeler et al[30] have characterized tubulocarcinomas of the breast. Although our tumors did mostly stain for E-cadherin as well, we do not think our tumors represent tubulolobular carcinomas as "this histologic pattern is distinct from other mixed ductal/lobular carcinomas in which the invasive components are often separate and the tubular component lacks a lobular growth pattern."…”

Histological type and typing of breast carcinomas and the WHO classification changes over time

“…In the 3 rd edition, it was also stated that E-cadherin studies should clarify the classification of TLCs as lobular or tubular. Such studies were performed before the publication of the 4 th edition, and they demonstrated strong membranous staining for E-cadherin (and the catenins if tested) in all 17 , 26 , 27 or the majority 28 of the overall 76 TLCs cases tested. Although these results and the three-dimensional reconstruction of TLCs 29 favor a wrong classification of TLC as lobular carcinoma variant, TLC has remained a variant/pattern of ILC in the latest edition, too 5 .…”

Histology of Luminal Breast Cancer

“…Tubulolobular IBC, which contains growth patterns of both ILBC and tubular carcinoma and is typically ER/PR positive and HER2 negative [63], is rather a variant of tubular/ductal carcinoma than of ILBC. Although mimicking the ILBC growth pattern, tubulolobular IBC displays retained membranous staining of E-cadherin, which is lost in classical ILBC [64, 65]. However, it has to be noted that the corresponding references are not mentioned in the 4th and 5th edition of the WHO Classification of Tumours of the Breast, in which tubulolobular carcinoma has been grouped as a variant of ILBC.…”