Lobular Carcinoma in Situ of the Breast
Definition
- A lesion composed of neoplastic lobular cells without stromal invasion
Alternate / historical names
- Lobular neoplasia
Diagnostic Criteria
- Uniform population of cells with round, sometimes eccentric nuclei
- Two cytologic types (mixtures and intermediate forms may occur)
- Classic
- Small round nucleli
- Fine chromatin, smooth nuclear contours
- Nucleoli small, inconspicuous
- Mitotic figures infrequent
- Has been subdivided as:
- Type A - small completely bland cells
- Type B - slightly larger, slightly irregular, small nucleoli
- Pleomorphic
- Moderately large nuclei
- Coarse chromatin
- Promininent nucleoli
- Mitotic figures not uncommon
- Central necrosis may be seen
- Requires confirmation of lobular nature with a negative E-cadherin stain
- Classic
- Lightly eosinophilic to vacuolated cytoplasm
- Signet ring cells may be present
- Two cytologic types (mixtures and intermediate forms may occur)
- Discohesive pattern
- Uniform cells (above) must fill all the acini in at least one lobular unit and half the acini must be expanded
- Expansion of acini apparent at low magnification
- Expanded acini typically balloon-like
- May form tiny acini but must not form cribriform spaces or micropapillae
- Pagetoid spread into ducts is common
- May completely fill ducts
- May involve sclerosing adenosis
- Lesions fulfilling some but not all required features of LCIS are considered Atypical Lobular Hyperplasia
Richard L Kempson MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: May 1, 2006