DCIS: Types and Clinical Behavior

Breast Cancer

• High risk of development of invasive breast cancer
• DCIS (Ductal Carcinoma In Situ) is a mammographically sensitive procedure for detection
• DCIS presents as calcifications, or less frequently as a vaguely palpable mass or nipple discharge

DCIS Subtypes

• Comedo type: 100% chance to develop invasive carcinoma if untreated
• Cribriform and micropapillary types: 30% chance to develop invasive carcinoma
• Other subtypes: solid, papillary

Paget's Disease of the Breast

• Rare manifestation of breast cancer (1-2%)
• Presents as a unilateral erythematous eruption with a scale crust
• Pruritus is common and may be mistaken for eczema
• Malignant cells (Paget cells) are found scattered in the epidermis
• Palpable mass is present in 50-60% of women, indicating an underlying invasive carcinoma

Lobular Carcinoma In Situ (LCIS)

• Uncommon and always an incidental finding in a biopsy performed for another reason
• Cannot be detected clinically, and mammography is not useful
• Frequently multicentric and bilateral
• Histology: monomorphic small round cells filling the acini of lobules
• Clinical behavior: 30% can develop into invasive cancer after 20 years of diagnosis if left untreated

Invasive Ductal Carcinoma (NOS)

• Grossly, firm, hard, and have an irregular border
• Characteristic grating sound when cut or scraped
• Accompanied by varying amounts of DCIS
• Histology: large and pleomorphic tumor cells, usually within a dense stroma, showing glandular formation

Invasive Lobular Carcinoma

• Second most common type, forming up to 10% of breast cancers
• May occur alone or in combination with ductal carcinoma
• Tends to be bilateral and multicentric
• Histology: single infiltrating malignant cells, forming a line (Indian file pattern)

Medullary Carcinoma

• Well-circumscribed mass, clinically and radiologically resembles fibroadenoma
• No desmoplasia, therefore soft and fleshy in consistency
• Histology: solid sheets of malignant cells surrounded by many lymphocytes and plasma cells, with scant fibrous stroma

Colloid (Mucinous) Carcinoma

• Tends to occur in older women
• Sharply circumscribed, lacks fibrous stroma, and is slow-growing
• Soft and has a glistening cut surface

Breast Cancer Risk Factors

• History of breast cancer or other cancer (e.g., ovary)
• Exercise: some studies showed decreased risk
• Breast-feeding: longer duration, lower risk
• Dietary factors: high fat diet and excessive alcohol consumption
• Environmental toxins: pesticides
• Radiation exposure: associated with increased risk for breast cancer

Breast Carcinoma Classification

• Majority of breast cancer is Adenocarcinoma
• Two major types: ductal and lobular
• Classified morphologically according to whether they have penetrated the basement membrane:
  • Carcinoma in situ (non-invasive)
  • Invasive carcinoma