# Rare “T-junction” aberrancy in vascular anatomy of the pectoral branch of the thoracoacromial trunk in the pectoralis major myocutaneous flap: A case report

## TL;DR

A rare vascular variation in the pectoralis major myocutaneous flap caused unexpected complications during surgery, highlighting the need for vigilance in flap harvesting.

## Contribution

This case report describes a previously undocumented 'T-junction' vascular aberrancy in the pectoral branch of the thoracoacromial trunk.

## Key findings

- The PB-TAT divided into medial and lateral branches in a 180-degree 'T-junction' before entering the pectoralis major muscle.
- The aberrant anatomy led to an unpremeditated ligation and on-table flap failure during surgery.
- This vascular variation has not been previously described in the literature.

## Abstract

Study Design: Case Report: The Pectoralis Major Myocutaneous Flap (PMMF) is easily harvested for Head and Neck reconstruction due to its consistent vascular anatomy and reliability of its main axial pedicle – Pectoral Branch of the Thoracoacromial Trunk (PB-TAT). Although the anatomical course of the PB-TAT is extensively studied, giving reconstructive surgeons the knowledge and confidence of utilising the PMMF in their armamentarium, we describe a case of its aberrancy which led to an unpremeditated ligation of this main pedicle, resulting in on-table flap failure. Instead of the expected submuscular course of the PB-TAT from the mid-clavicular line to join the acromio-xiphoid axis as it courses medially in a cranio-caudal fashion, we identified this pedicle in our case to divide into its medial and lateral branches in a 180 degrees “T-junction” fashion as it approaches the acromio-xiphoid axis, and entering the pectoralis major muscle only after a short extra muscular course. Despite harvesting the lateral extent of the PMMF further lateral to where the lateral branch of the PB-TAT entered the muscle, majority of the flap was not bleeding after elevation, suggesting an inadvertent ligation of this main pedicle. Although the vascular anatomy of the PMMF has been extensively studied in the literature, we believe this aberrancy in the course of the PB-TAT has not been described, and hope to share this encounter with other reconstructive surgeons, to be vigilant and mindful even when raising a ‘straight-forward’ flap.