Infiltrating Lobular Carcinoma of the Breast

Supplemental Studies

Demonstration of myoepithelial cells can confirm the in situ nature of a process while their absence supports invasion

Marker	Sensitivity	Specificity
Calponin	Excellent	Very good
p63	Excellent	Excellent
Smooth muscle myosin heavy chain	Good	Excellent
CD10 (CALLA)	Good	Good
High molecular weight cytokeratin	Very good	Poor
Maspin	Good	Poor
S100	Good	Very poor
Actin	Good	Very poor

E-cadherin appears to be a sensitive marker of ductal differentiation vs lobular differentiation; its utility in borderline lesions is currently uncertain

E-cadherin is reported to be negative in the pleomorphic variant and positive in the tubulo-lobular variant

	GCDFP15 (BRST2)	Estrogen Receptor	Progesterone Receptor
Infiltrating ductal carcinoma	60-70%	75%	50-60%
Infiltrating lobular carcinoma	60-70%	>95%	80%
Lung adenocarcinoma	0-1%	<5%	<5%
Ovarian adenocarcinoma	1-5%	50-100%	40-90%
Endometrioid adenocarcinoma	negative	70%	70%
GI adenocarcinoma	negative	<5%	1-10%
Pancreatic adenocarcinoma	negative	negative	0-5%
Cholangiocarcinoma	negative	negative	30%
Thyroid carcinoma	negative	20%	30%

Sweat gland and salivary gland neoplasms may also be positive for GCDFP15, ER and PR
Prostatic adenocarcinoma may be positive for GCDFP15

CK7 and CK20 do not distinguish breast from lung adenocarcinomas but may help in the distinction from ovary, pancreas, bile duct and GI carcinomas.

CK7 and CK20 expression in carcinomas
CK7+20+	CK7-20+
Ovary mucinous 90%	Colorectal adeno 80%
Transitional cell 65%	Merkel cell 70%
Pancreas adeno 65%	Gastric adeno 35%
Cholangio 65%
Gastric adeno 40%
Excluded tumors 5% or less Carcinoid; Germ cell; Esoph squam; Head/neck squam; Hepato-cellular; Lung small cell & squam; Ovary non-mucinous; Renal adeno	Excluded tumors 5% or less Breast; Carcinoid lung; Cholangio; Esoph squam; Germ cell; Lung all types; Hepato-cellular; Ovary; Pancreas adeno; Renal adeno; Transitional cell; Uterus endometrioid
CK7+20-	CK7-20-
Ovary non-mucinous 100%	Adrenal 100%
Thyroid (all 3 types) 100%	Seminoma & Yolk Sac 95%
Breast 90%	Prostate 85%
Lung adeno 90%	Hepatocellular 80%
Uterus endometrioid 85%	Renal adeno 80%
Embryonal 80%	Carcinoid intestinal & lung 80%
Mesothelioma 65%	Lung small cell & squam 75%
Transitional cell 35%	Esoph squam 70%
Pancreas adeno 30%	Head/neck squam 70%
Cholangio 30%	Mesothelioma 35%
Excluded tumors 5% or less Colorectal adeno; Ovary mucinous; Yolk Sac; Seminoma	Excluded tumors 5% or less Breast; Cholangio; Lung adeno; Ovary; Pancreas adeno

Broad spectrum antikeratin stains may be particularly useful for the identification of lobular carcinoma in lymph nodes

Estrogen receptor (ER) and progesterone receptor (PR) are important markers for directing therapy and determining prognosis
- Current consensus is that any level of positivity should be reported as positive
Her2neu status can be determined by either immunohistology or by FISH
- The other technique can be used for borderline case

Her2neu status can be determined by either immunohistology or by FISH
- The other technique can be used for borderline cases