Histology of invasive ductal carcinoma classically shows?

• A. Nests of glandular tissue surrounded by dense desmoplastic stroma
• B. Sheets of small round blue cells with scant cytoplasm
• C. Keratin pearls within squamous nests
• D. Granulomatous inflammation with giant cells

Answer: (A)

Invasive ductal carcinoma characteristically shows malignant ductal cells infiltrating the surrounding breast tissue with a pronounced desmoplastic (dense fibrous) stromal reaction. This means nests or cords of gland-forming tumor cells are embedded in a heavy fibrous stroma created by the surrounding fibroblasts in response to invasion. This desmoplastic background is a classic hallmark of invasive carcinomas in the breast and helps distinguish invasive disease from noninvasive lesions.

The other patterns point to different conditions: sheets of small round blue cells suggest other small round blue cell tumors; keratin pearls within squamous nests indicate squamous differentiation; granulomatous inflammation with giant cells fits granulomatous processes like certain infections or sarcoidosis.