Infiltrating Syringomatous Adenoma of the Nipple

Differential Diagnosis

Infiltrating Syringomatous Adenoma of the Nipple	Low Grade Adenosquamous Carcinoma
Involves dermis and subcutis	Parenchymal lesion
No metastases reported	Infrequent metastases reported

Some consider these to be the same entity in different locations

Histologic appearance is identical

Small numbers of cases and differences due to superficiality could account for the difference in behavior reported

Nipple Adenoma	Infiltrating Syringomatous Adenoma of the Nipple
May have compressed ducts at edges but predominantly papillomatous	Irregular, frequently compressed lumens throughout
Localized although not completely circumscribed	Infiltrative
Stroma non-reactive	Desmoplastic stroma

Squamous metaplasia may be present in papillomatosis resulting in confusion with syringomatous adenoma

Tubular Carcinoma	Infiltrating Syringomatous Adenoma of the Nipple
Uniform, gaping tubules	Irregular, frequently compressed lumens
Tubules frequently have pointed ends	Tubules frequently have long comma-shaped tails
No squamous differentiation	At least focal squamous differentiation
No myoepithelial component	Myoepithelial cells present around tubules