Tubulolobular carcinoma of the breast

Definition

This is a rare subtype of breast carcinoma intermediate between ductal and lobular in differentiation. A criterion of 75% of the tumour showing a tubulolobular pattern has been set. They represent less than 3% of all breast carcinomas.

Histopathology

The tumour consists of an admixture of small tubules and cell cords. The tubules are round, lacking the angularity (comma shape) and apical snouts typical of tubular carcinoma. Both components permeate in a targetoid pattern as for lobular carcinoma. A minor component (<25% of the tumour) may be pure tubular or pure lobular: collision tumours are excluded. In most cases the cells are small with little cytoplasm and inconspicuous nucleoli. Some cases show apocrine metaplasia with eosinophilic cytoplasm, larger nuclei and more prominent nucleoli. An in-situ component is common and may be lobular or mixed, less often pure ductal. There may be perineural invasion.

Lymph node metastases were reported in 3/16 staged cases, with a predominance of tubules , some cribriform glands and a higher nuclear grade in the metastases2.

Immunohistochemistry

The immunophenotype of both tubulolobular and tubal carcinoma is the same as that of ductal carcinoma.

	Tubulolobular carcinoma		Pure tubular carcinoma	Pure lobular carcinoma
	tubular component	cell cords
E-cadherin	27/27(all cases were intensely positive)1	27/271	5/51, 10/102	0/51, 0/102
	18/18(membranous)2
34bE12	25/271	25/27(staining was often paranuclear)1	5/51, 5/102	4/51, 5/102
	10/17(cytoplasmic)2
ER	17/17(intense positivity)1, 18/192		10/102	10/102
PR	16/17(intense positivity)1, 15/192		9/102	9/102
Her-2	0/101, 4/19(scores of 2 or 3 considered positive)2		2/10(scores of 2 or 3 considered positive)2	2/10(scores of 2 or 3 considered positive)2
a-catenin	14/14(membranous)2		9/9(membranous)2	0/102
b-catenin	18/18(membranous)2		10/102	10/10(staining was purely cytoplasmic)2
g-catenin	15/15(membranous)2		10/10(membranous)2	10/102
p120 catenin	18/18(membranous)2		10/10(membranous)2	10/10(staining was purely cytoplasmic)2

Prognosis

The prognosis is probably better than for pure lobular but worse than for pure tubular carcinoma. 3/241 patients developed axillary metastases and 1/241 developed a local recurrence. In another series, 2/19 patients developed recurrences, of whom one had widespread metastases2.

References

1 Wheeler, D. T., L. H. Tai, et al. (2004). "Tubulolobular carcinoma of the breast: an analysis of 27 cases of a tumor with a hybrid morphology and immunoprofile." Am J Surg Pathol 28(12): 1587-93.

2 Esposito NN, Chivukula M,Dabbs DJ. The ductal phenotypic expression of the E-cadherin/catenin complex in tubulolobular carcinoma of the breast: an immunohistochemical and clinicopathologic study. Mod Pathol 2007; 20:130-8

This page last revised 20.1.2007.