Surgical Pathology Criteria

Infiltrating Lobular Carcinoma of the Breast

Differential Diagnosis

Infiltrating Ductal Carcinoma Infiltrating Lobular Carcinoma
Infiltration in cords of varying thickness Single file infltration
May form ductal structures No duct formation
E-cadherin positive E-cadherin negative
The utility of E-cadherin in borderline cases is currently uncertain


Tubulolobular Carcinoma Infiltrating Lobular Carcinoma
Contains a tubular component Uniform single file pattern
E-cadherin positive E-cadherin negative
Some consider tubulolobular carcinoma to be a variant of lobular carcinoma


Early stromal invasion in lobular carcinoma can be difficult to distinguish from LCIS involving sclerosing adenosis
LCIS in Sclerosing Adenosis Infiltrating Lobular Carcinoma
Circumscribed, nodular Infiltrating, not confined to nodule
Myoepithelial cells present Myoepithelial cells absent in infiltrating areas


Lymphocytes and histiocytes in breast stroma and lymph nodes can be difficult to distinguish from lobular carcinoma
Inflammation Infiltrating Lobular Carcinoma
No molding of nuclei Molding of nuclei
Single file pattern unusual Single file pattern common
No mucin positive signet ring cells Mucin positive signet ring cells may be present
Keratin negative Keratin positive


Lymphoma may be diffcult to distinguish from alveolar and solid variants of lobular carcinoma
Lymphoma Infiltrating Lobular Carcinoma
No molding of nuclei Molding of nuclei
Lymphoid markers positive Keratin positive


Mucinous Carcinoma vs. Signet Ring Carcinoma


Signet Ring Carcinoma Secretory Carcinoma
One or few vacuoles that indent nucleus Abundant granular to clear cytoplasm
May be nuclear grade I or II Low nuclear grade
Often associated with classic lobular carcinoma pattern No association with lobular carcinoma
No predilection for young patients Most cases <30 years
May show aggressive behavior Excellent prognosis
Signet ring carcinoma is usually a variant pattern of lobular carcinoma


Breast vs. other origin in carcinoma of unknown primary

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