intracystic papillary carcinoma

Definition: Intracystic papillary carcinoma has malignant papillae with true fibrovascular cores within a duct. It has a relatively good prognosis.

Intracystic papillary carcinoma (IPC) is regarded as an intraductal neoplasm, but recent evidence suggests that it could be invasive, as it often lacks myoepithelial lining.

Intracystic papillary carcinoma has malignant papillae with true fibrovascular cores within a duct. It has a relatively good prognosis.

Differential diagnosis

 lobular carcinoma in situ / LCIS

• LCIS has uniform, loosely cohesive cells. It is E-Cadherin negative, and commonly in the breasts bilaterally.

 micropapillary ductal carcinoma in situ / micropapillary DCIS

• Micropapillary DCIS has a myoepithelial layer surrounding the duct, and malignant cells project into the lumen.
• The papillary-like structures do not have fibrovascular cores.
• They are more narrow at the base, expand towards the lumen, and form bridges. 1/4 are multifocal.

 flat epithelial atypia

• FEA shows one to two columnar cell layers within the duct, with mild atypia and apical snouts.
• FEA is associated with tubular and lobular carcinomas.

 mammary tubular carcinoma

• Glands of tubular carcinoma are “boat” or “comma” shaped with a single lining of malignant cells with low pleomorphism, in a background of fibroplasia.