Single file pattern is seen in breast cancer type?
**Core Concept**
The single file pattern is a characteristic histopathological feature of certain types of breast cancer, reflecting the manner in which cancer cells infiltrate the stroma. This pattern is associated with **invasive lobular carcinoma**, a subtype of breast cancer. The single file pattern is indicative of the discohesive nature of the cancer cells.
**Why the Correct Answer is Right**
Invasive lobular carcinoma is known for its distinctive single file pattern, where malignant cells infiltrate the stroma in a linear, single-file fashion. This is due to the loss of **E-cadherin** expression, a cell adhesion molecule that helps maintain cell cohesion. The absence of E-cadherin leads to a discohesive growth pattern.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not typically display a single file pattern.
**Option B:** Incorrect as it is not characteristically associated with this pattern.
**Option D:** Incorrect because it is not the correct type of breast cancer associated with the single file pattern.
**Clinical Pearl / High-Yield Fact**
The single file pattern is a key diagnostic feature of invasive lobular carcinoma, which can be challenging to diagnose due to its subtle appearance on mammography and histology. Recognizing this pattern is crucial for accurate diagnosis.
**Correct Answer:** D. Invasive lobular carcinoma