Treatment of Lobular Carcinoma In Situ of the Breast in Non-Classic LCIS (Pleomorphic or Florid Variant)
Non-classic lobular carcinoma in situ (LCIS) encompasses two high-risk histologic variants — pleomorphic LCIS and florid LCIS — that carry a significantly elevated risk of upgrade to invasive disease compared with classic LCIS, and therefore require a distinct management approach.
Clinical Scenario
Pleomorphic LCIS (PLCIS) is characterised by large pleomorphic cells with marked nuclear atypia, comedonecrosis, and microcalcifications, resembling ductal carcinoma in situ. Florid LCIS (FLCIS), recognised by the WHO in 2019 as a distinct variant, is defined by marked mass-forming distention of the terminal ductal lobular unit acini with minimal intervening stroma.
Treatment Approach
Because of the high upgrade rate to invasive cancer or DCIS (30–40%), the recommended approach for non-classic LCIS involves surgical intervention with specific margin requirements.
Full margin criteria, surgical details, and the complete evidence-based regimen are available via the structured protocol.
References
- Pleomorphic LCIS (PLCIS) is a rare variant of LCIS characterized by large pleomorphic cells with marked nuclear atypia, comedonecrosis, and microcalcifications similar to DCIS.
- Florid LCIS (FLCIS) was recognized in 2019 by the World Health Organization (WHO) as a distinct LCIS variant, characterized by marked mass-forming distention of the TDLU acini with minimal intervening stroma.
- It is recommended that PLCIS be surgically excised with negative margins due to its multifocal nature and high rate of associated invasive disease.
- Therefore, for PLCIS, 2mm margins are recommended similar to the Society of Surgical Oncology/American Society for Radiation Oncology/American Society of Clinical Oncology Consensus Guideline on Margins for ductal carcinoma in situ.
- The upgrade rate to invasive cancer or DCIS is 30–40%, so surgical excision with 2mm margins is recommended to exclude upgrade to malignancy similar to PLCIS.
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