Table 1 Summary of Characteristics of Breast Lesions Observed in the Human Versus the Rat

From: A Comparison of the Histopathology of Premalignant and Malignant Mammary Gland Lesions Induced in Sexually Immature Rats with those Occurring in the Human

 

Human

Rat

Normal

• Luminal epithelium and myoepithelial cell layer

Same as human

Benign lesions

• Fewer epidermal inclusion cysts

• Epidermal inclusion cysts are relatively frequent, and occur within the mammary lobules also

 

• Fibroadenomas may occasionally display ADH and CIS

• No ADH or CIS within fibroadenomas

 

• A wide spectrum of benign lesions occurs

• A very limited number of benign lesions, including fibroadenoma, papilloma

Hyperplasia

• Special types of hyperplasia may occur

• Hyperplasia of the usual type is seen; no special types of hyperplasia

ALH

• May be observed

• Not observed

DCIS

• Many histologic subtypes of CIS

• Cribriform and papillary DCIS

  

• No true micropapillary, comedo and apocrine DCIS

 

• There may be elastosis and microcalcifications

• No elastosis and microcalcifications

Carcinoma

• There may be a single file pattern of invasion by carcinoma cells

• Broad front of stromal invasion, and not as single cells

 

• Many special types of carcinomas

• No tubular, mucinous, adenoid cystic, medullary and lobular carcinoma

 

• Lymph node involvement is frequent

• Lymph node involvement is infrequent

Back to article page