Florid Hyperplasia with Clear Cells

Atypical Lobular Hyperplasia (ALH)

Age

Adult women

Adult women, incidence drops following menopause

Imaging findings

Incidental finding or associated with calcifications

Incidental finding, rarely associated with calcifications

Etiology

Unknown

Unknown

Histology

1. 
   

   Lobular unit expanded by a proliferation of nonuniform epithelial cells with residual secondary lumens (Fig. 3.1.1)

   
   
2. 
   

   Secondary spaces are irregular, with a slit-like arrangement (Figs. 3.1.2, 3.1.3, 3.1.4)

   
   
3. 
   

   Nuclear variability and overlap are evident (Figs. 3.1.2, 3.1.3, 3.1.4)

   
   
4. 
   

   Indistinct cell borders (Figs. 3.1.3 and 3.1.4)

1. 
   

   Lobular units contain a uniform cell population, with some filling of acini by small cells with a dyshesive growth pattern (Figs. 3.1.5 and 3.1.6)

   
   
2. 
   

   Acini contain characteristic cells, but are not fully distended, and are not distorted (Figs. 3.1.5, 3.1.6, 3.1.7, 3.1.8)

   
   
3. 
   

   Residual luminal epithelial and myoepithelial cells are present (Figs. 3.1.7 and 3.1.8)

   
   
4. 
   

   Intracytoplasmic inclusions are common (Fig. 3.1.8)

Special studies

None; CK5/6 may be variably expressed

None; E-cadherin is usually not expressed; p120 expression maintained

Genetic abnormalities

None

Mutations of CDH1 (chromosome 16q22.1)

Treatment

None

Excision not required if incidental finding on core biopsy; mammographic follow-up ± antiestrogen therapy

Clinical implication

Slightly increased risk of later cancer development (1.5×); magnitude of risk insufficient to affect patient management

Moderately increased risk of later cancer development (4-5×); bilateral risk with ipsilateral breast at greater (3:1) risk

Usual Hyperplasia with Prominent Myoepithelial Cells

ALH

Age

Adult women

Adult women, incidence drops following menopause

Imaging findings

Incidental finding, or associated with calcifications

Incidental finding, rarely associated with calcifications

Etiology

Unknown

Unknown

Histology

1. 
   

   Nonuniform cellular proliferation involving clustered lobular units (Fig. 3.2.1)

   
   
2. 
   

   Mixture of cell types; myoepithelial cells are recognized by clear cytoplasm and peripheral location while central luminal epithelial cells have eosinophilic cytoplasm (Figs. 3.2.1, 3.2.2, 3.2.3, 3.2.4)

   
   
3. 
   

   Nuclear variability and overlap are present in both cell populations (Figs. 3.2.2, 3.2.3, 3.2.4)

   
   
4. 
   

   Irregular secondary spaces and myoepithelial cells with clear cytoplasm (Figs. 3.2.2, 3.2.3, 3.2.4)

   
   
5. 
   

   Myoepithelial cells lack intracytoplasmic inclusions (Figs. 3.2.2, 3.2.3, 3.2.4)

1. 
   

   Lobular units are variably populated by uniform cells with a dyshesive growth pattern (Figs. 3.2.5 and 3.2.6)

   
   
2. 
   

   Evenly placed, uniform cells lack welldefined cellular borders, and acini are not filled or distended (Figs. 3.2.6, 3.2.7, 3.2.8)

   
   
3. 
   

   Intracytoplasmic inclusions are frequent (Fig. 3.2.8)

   
   
4. 
   

   Acini are closely opposed, but intervening stroma is evident (Fig. 3.2.8)

Special studies

None; CK5/6, and E-cadherin diffusely expressed

None; E-cadherin is usually not expressed, intact p120 expression

Genetic abnormalities

None

Mutations of CDH1 (chromosome 16q22.1)

Treatment

Excision unnecessary if detected in core biopsy specimen

Excision not required if incidental finding on core biopsy; mammographic follow-up ± antiestrogen therapy

Clinical implication

Risk implications apply only when present admixed with florid hyperplasia, the latter being the risk-indicator lesion; slightly increased risk of later cancer development (1.5×); risk is bilateral. Risk level is insufficient to affect patient management.

Moderately increased risk of later cancer development (4-5×); bilateral risk with ipsilateral breast at greater (3:1) risk