Fat necrosis in level I oncoplastic breast-conserving surgery focusing on a modified round block technique

  • Hisamitsu ZahaEmail author
  • Tokiwa Motonari
  • Norie Abe
  • Mikiko Unesoko
Original Article


The modified round block technique (MRBT) is a level I oncoplastic breast-conserving surgery (OBCS), which contains a very wide glandular flap created by extensive dual-plane undermining that is achieved by entire subcutaneous dissection and approximately 50% dissection of the breast parenchyma from the pectoralis muscle. A retrospective analysis was performed for 100 patients who underwent OBCS using MRBT from February 2009 to October 2017. The incidence of positive margin was 7.0% (seven cases), and there has been no local recurrence during a median follow-up period of 68 months. Short- and long-term complications included fat necrosis (11.0%), infection (4.0%), and hematoma formation (4.0%). When patients were divided into two groups based upon the preoperative mammography findings, fat necrosis occurred in 5.2% of the patients with extremely dense or heterogeneously dense mammography, and in 19.0% of patients with scattered fibroglandular or entire fat mammography, which showed a statistically significant difference. Therefore, in level I OBCS, the extent of dual-plane undermining should be minimized to less than 50% of the total parenchyma in fatty breasts.


Breast-conserving surgery Oncoplastic surgery Modified round block technique Fat necrosis 



This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Compliance with ethical standards

Conflict of interest

Hisamitsu Zaha declares that he/she has no conflict of interest. Tokiwa Motonari declares that he/she has no conflict of interest. Norie Abe declares that he/she has no conflict of interest. Mikiko Unesoko declares that he/she has no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© The Japanese Breast Cancer Society 2020

Authors and Affiliations

  • Hisamitsu Zaha
    • 1
    Email author
  • Tokiwa Motonari
    • 1
  • Norie Abe
    • 1
  • Mikiko Unesoko
    • 1
  1. 1.Department of Breast SurgeryNakagami HospitalOkinawa CityJapan

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