When extensive and complex tumors are resected in oral cancer patients, large soft tissue defects often result. Reconstruction of these large soft tissue defects is essential to restore function and achieve aesthetic outcomes. Conventional reconstruction methods for large defects have primarily used free flaps such as the latissimus dorsi (LD) flap^1-3 and the anterolateral thigh (ALT) flap^3-6.

The LD flap features consistent anatomy with a dependable pedicle, providing substantial length and width. However, simultaneous harvesting of the flap during head and neck cancer surgery is difficult because it increases operation time and requires patient position change intraoperatively³. The LD donor site has significant morbidity, including potential seroma formation and impaired shoulder function. Additionally, the LD muscle is often too bulky for intraoral cavity reconstruction due to the subcutaneous fat layer^7,8.

The ALT flap possesses several advantageous characteristics that make it an ideal donor site for soft tissue reconstruction in the head and neck region. These favorable traits include an extensive amount of thin, flexible skin, a lengthy vascular pedicle, and a suitable pedicle diameter. Most donor sites for the ALT flap can be closed primarily, resulting in low donor site morbidity. Additionally, the ALT flap allows a two-team approach and does not require intraoperative position change for the patient^5,6,9.

However, the ALT flap alone may have limitations when it is used to cover multiple large defects. To overcome these limitations, a chimeric ALT flap can be considered¹⁰. A chimeric flap consists of separate components, each with its own vascular supply, which are all attached to a larger common source vessel. This configuration allows multiple pedicles to be included in a single flap, providing versatility and adaptability for more complex reconstructions^11,12. Therefore, the chimeric ALT flap provides versatility for reconstructing more extensive and multidimensional complex head and neck defects, while retaining the advantages of the ALT flap^5,10,13,14.

In this case series, we present our experience using a chimeric ALT flap based on perforators from the descending branch of the lateral circumflex femoral artery (LCFA) for reconstruction of extensive head and neck defects following resection of tumors in oral cancer patients.

This study was reviewed and approved by the Institutional Review Board (IRB) of Asan Medical Center (IRB approval No. S2024-1727-0001). Informed consent was not required for the case report as no patient-specific information was disclosed.

1. Case 1: Multiple defects

The patient is a 50-year-old male with squamous cell carcinoma (SCC) (T4bN2bM0) of the right mandible who presented with a large oral mass and skin involvement.(Fig. 1) Wide tumor resection including a segmental mandibulectomy from the left mandibular canine to the right mandibular ramus was performed, leading to intraoral and extraoral defects.(Fig. 2. A) A chimeric flap with two perforators from a single common source vessel was designed to match the defect size of both intraoral and extraoral areas. Dissection was performed following the usual ALT flap harvesting method, and the descending branch of the LCFA was identified. Two pedicles, each with a single perforator, were harvested.(Fig. 2. B) The flap size was 13 (length)×9 cm (width) for the extraoral flap and 11 (length)×6 cm (width) for the intraoral flap. Reconstruction of the mandible was performed using a reconstruction plate (R-plate), and the skin paddles were positioned and sutured to the intraoral and extraoral soft tissue defects. At the final follow-up visit one year after surgery, no recurrence was observed at the primary tumor site or in the cervical lymph nodes.(Fig. 3)

2. Case 2: Dimensional modification

An 83-year-old male patient with SCC (T4aN0M0) of the posterior gingiva on the right mandible underwent a hemimandibulectomy extending from the left mandibular lateral incisor to the right mandibular ramus. A wide flap was needed to cover the large soft tissue defect. Direct closure of the donor site is preferred to minimize postoperative complications and facilitate easier postoperative management. However, harvesting a very wide ALT flap complicates direct closure. Therefore, a chimeric ALT flap with two narrow pedicles was harvested from the left thigh and was dimensionally modified to fit the defect size.(Fig. 4. A, 4. B) By combining these two narrow flaps, we were able to cover the wide defect.(Fig. 4. C) Although flap transplantation was successful, the patient experienced recurrence at the primary site one month post-surgery. Biopsy results confirmed spindle cell SCC. The patient was scheduled for postoperative chemoradiotherapy but passed away before treatment could begin.

3. Case 3: Extensive tissue damage

A 62-year-old male with SCC (pT4bN3bM0) involving the right retromolar trigone underwent a segmental mandibulectomy, extending from the right mandibular canine to the mandibular ramus, along with a right modified radical neck dissection 1 year prior to presentation. After the surgery, he received both radiation therapy and chemotherapy, but the cancer recurred at the primary site. Prior to the resection and reconstruction of the recurrent tumor, the patient presented with through-and-through exposure at the surgical site, an exposed R-plate, significant tissue loss, and fibrosis with multiple scars.(Fig. 5) A chimeric ALT flap was designed and harvested to cover the mandibular defects, with one paddle (10×7 cm) covering the extraoral area and the other (6×4 cm) covering the intraoral area.(Fig. 6) The chimeric flap integrated well, and the surgical site showed excellent healing after the operation.(Fig. 7) As of the last follow-up visit, 6 months post-reoperation, there were no signs of recurrence, and the healing process was satisfactory.(Fig. 8)

This series of three cases presents the use of the chimeric ALT flap to reconstruct complex and large soft tissue defects in patients with oral cancer. These cases demonstrate application of the chimeric ALT flap in extensive tissue reconstruction, showcasing its benefits and confirming its safety and reliability as a reconstructive option.

In the first case, reconstruction of multiple extensive defects in both intraoral and extraoral regions was achieved with a single flap. This case emphasizes the capability of the chimeric ALT flap to cover large volumes of soft tissue that a single ALT flap cannot. The effectiveness and versatility of chimeric flaps for large defect reconstruction have been well-documented in previous studies. These studies have reported successful outcomes using various types of chimeric flaps, including the ALT/anteromedial thigh^13,15, ALT/vastus lateralis chimeric flaps^16,17, and ALT/ALT chimeric flaps^4,5,9 as demonstrated in this study. To address multiple defects, options such as a double free flap, two separate flaps, or a double island flap can be used in addition to a chimeric flap. However, the chimeric flap offers significant advantages over the double free flap by reducing surgical complexity and time and provides greater flexibility and adaptability for complex reconstructions compared to the double island flap.

The second case that the chimeric ALT flap can be reconfigured through dimensional modification to fit the defect appropriately. This case illustrates the combination of two narrow paddles into one wide flap to reconstruct a wide defect with direct closure. The advantage of this approach is that each original flap remains narrow enough to allow direct closure of the donor site, which minimizes donor site complications and provides better aesthetic results. The LD flap is often used to cover extensive surgical areas; however, the chimeric ALT flap does not require patient position change during surgery and allows a two-team approach that can reduce operative time. Additionally, the ALT flap has thinner and more flexible tissue along with a longer and more reliable vascular pedicle, making it a more convenient and versatile option.

The third patient had a history of radiation therapy and needed reconstructive surgery due to recurring cancer. Radiation therapy often decreases the flexibility of soft tissues, leads to fibrosis, and increases the risk of vascular damage. Consequently, reconstruction in previously irradiated areas can be especially challenging and complex. The chimeric flap can cover a broad area with multiple paddles, which enhances the flexibility and adaptability of the reconstruction. A chimeric flap also provides various tissue types, such as skin, fat, and muscle, in one flap, meeting the diverse requirements of defects after surgery^17-20. Furthermore, it includes independent perforators, ensuring stable blood supply even in cases with compromised vascular conditions due to radiation therapy²⁰.

This study demonstrates the significant advantages and potential of chimeric flaps in reconstructing large soft tissue defects. However, this study did not conduct a direct comparison with the outcomes of single large ALT flaps and cannot conclude superiority of chimeric ALT flaps. Single ALT flaps can also be harvested in large sizes, while the chimeric flap technique requires higher surgical expertise to locate the perforators. To determine the comparative advantages of chimeric ALT flaps over single ALT flaps for large defect reconstruction, further studies with larger patient cohorts and long-term follow-up are required.

This case series demonstrates that the chimeric ALT flap may be a more effective option than traditional single-pedicle ALT flaps for patients with multiple large defects, those requiring dimensional modification, or those with extensive tissue damage.

All authors participated in the surgery. K.M.A. and J.H.L. collected the raw data. H.S.K. reviewed the article and wrote the manuscript. J.H.L. supervised the revision of the manuscript. All authors reviewed and approved the final manuscript.

This study was reviewed and approved by the Institutional Review Board (IRB) of Asan Medical Center, Seoul, Korea (IRB approval No. S2024-1727-0001). Informed consent was not required for the case report as no patient-specific information was disclosed.

No potential conflict of interest relevant to this article was reported.