A 58-year-old woman is referred to a general surgeon after a routine screening mammogram demonstrated an area of architectural distortion in the left breast. She has no palpable breast masses, nipple discharge, or overlying skin changes. A core needle biopsy of the abnormal area is performed. The pathology report indicates an invasive breast malignancy characterized by a complete loss of E-cadherin expression due to a mutation in the CDH1 gene. Based on this molecular profile, which of the following histopathologic findings is most likely present on the biopsy specimen?
- Small, monomorphic cells infiltrating the stroma in a single-file linear patternAnswer
- BInfiltrating malignant cells forming irregular glandular structures within a desmoplastic stroma
- CSolid sheets of pleomorphic cells surrounded by a dense lymphoplasmacytic infiltrate
- DDistended ducts filled with pleomorphic cells and areas of central comedonecrosis
- EComplex arborizing papillae lined by atypical epithelial cells without a myoepithelial layer
Answer
Small, monomorphic cells infiltrating the stroma in a single-file linear pattern
The correct answer accurately describes the pathognomonic histology of invasive lobular carcinoma (ILC). The loss of E-cadherin, a cell surface protein responsible for intercellular adhesion encoded by the CDH1 gene, causes the neoplastic cells to lose their cohesiveness. Consequently, they do not form glands or ducts. Instead, they infiltrate the breast stroma individually or in classic linear cords, commonly referred to as a 'single-file' pattern.
Step-by-Step Solution
Key Concept
Correlation of E-cadherin loss (CDH1 mutation) with the single-file histologic pattern of Invasive Lobular Carcinoma.