E-cadherin and loss of heterozygosity at chromosome 16 in breast carcinogenesis: different genetic pathways in ductal and lobular breast cancer?

Loss of heterozygosity at the long arm of chromosome 16 is one of the most frequent genetic events in breast cancer. In the search for tumour suppressor genes that are the target of loss of heterozygosity at 16q, the E-cadherin gene CDH1 was unveiled by the identification of truncating mutations in the retained copy. However, only lobular tumours showed E-cadherin mutations. Whereas investigations are still devoted to finding the target genes in the more frequent ductal breast cancers, other studies suspect the E-cadherin gene to also be the target in this tumour type. The present article discusses the plausibility of those two lines of thought

The significance of lobular neoplasia on needle core biopsy of the breast

The management of a core biopsy diagnosis of lobular neoplasia is controversial. Detailed radiological–pathological review of 47 patients with cores showing classical lobular neoplasia was performed (patients with pleomorphic lobular carcinoma in situ (LCIS) or associated risk lesions were considered separately). Immediate surgical excision in 25 patients showed invasive carcinoma in 7, ductal carcinoma in situ (DCIS) in 1 and pleomorphic LCIS in 1; radiological–pathological review showed that the core biopsy missed a mass in 5, missed calcification in 2 and that calcification appeared adequately sampled in 2. Nineteen patients had follow-up of at least 2 years. Four patients developed malignancy at the site of the core biopsy (invasive carcinoma in three, DCIS in one); one carcinoma was mammographically occult, one patient had dense original mammograms and two had calcifications apparently adequately sampled by the core. In conclusion, most carcinomas identified at the site of core biopsy showing lobular neoplasia were the result of the core missing the radiological lesion, emphasising the importance of multidisciplinary review and investigation of any discordance. Some carcinomas were found after apparently adequate core biopsy, raising the question of whether excision biopsy should be considered after all core biopsy diagnoses of lobular neoplasia