Pectoralis major myocutaneous - A work horse flap in intraoral reconstruction: A case report

INTRODUCTION

Among all malignancies affecting the oral cavity, oral squamous cell carcinoma (SCC) is the most common one and a leading cause of death in India. Oral cancer accounts for nearly 7% death rate among males and 4% among females annually.^[1,2] This may be attributed to tobacco addiction, particularly its use in smokeless tobacco form, that is, chewing or placement of quid in the gingivobuccal sulcus. As a tertiary center in the central part of India, most of our patients present with advanced T4-stage disease, making soft-tissue reconstruction a surgical challenge, resulting in significant deformity.^[3] The choice of reconstruction is primarily influenced by the reconstruction ladder, preexisting comorbidities, nutritional condition, and lastly economic status of the patient.^[4-6]

The continuity of the mandible is of paramount importance with regard to the maintenance of airway, swallowing, and articulation of speech. Considering this, the management of SCC involving the mandible has changed significantly with the increasing knowledge on patterns of mandibular invasion by the tumor.^[7-10] Reconstruction focuses on restoring esthetics while achieving a favorable functional outcome. Cosmetic complications include the well-known Andy Gump deformity and lower lip retraction. Functional challenges may involve difficulties with speech, swallowing, drooling, chewing, and the potentially hazardous tongue fall, which can obstruct the airway.^[11,12]

While free flaps have been the primary choice for soft-tissue reconstruction in recent decades, but it needs surgical expertise, training and specialized equipment, hence, in the resource constrained setups, the pectoralis major myocutaneous (PMMC) flap remains a reliable option for oral malignancies, particularly in patients with specific indications and with chronic comorbidities.^[4-6] Free flap reconstruction is always a lengthier technique sensitive procedure compared to pedicle flaps, making it challenging to manage the high patient load of oral malignancies. The PMMC flap was first introduced by Ariyan in 1979 for primary reconstruction of oncologic defects and salvage surgery in recurrent oral cancers.^[13,14] PMMC flap continues to be the workhorse flap for head-and-neck reconstruction as it is a reliable, simple, and cost-effective option.

This case report aims to highlight the versatility of PMMC flap in reconstruction of large mandibular defects due to oral malignancy.

CASE REPORT

A 56-year-old male patient reported to the department of oral and maxillofacial surgery with the chief complaint of pain and swelling in the lower left back region of the jaw from 2 months. Initially, the swelling over the lower left side of jaw was small in size, which gradually increased to attain the presenting size. The pain was dull aching, mild and intermittent type which aggravated on mastication. On intraoral examination in the lower left posterior region, gingiva buccal sulcus, an ulcero-proliferative growth in the lower left gingiva buccal sulcus, was present which has slowly increased in size over the period of 2 months, which bleeds on touch. There was a history of burning sensation associated with the consumption of hot and spicy food. There was no history of loss of appetite or significant weight loss. The patient had no other relevant medical or dental history contributing to this case. The patient gave a habit history of consumption of areca nut, gutkha, and tobacco from 9 years, nearly 6–7 times a day, and alcohol consumption thrice a day from 9 years.

On extraoral examination, the face was slightly asymmetrical due to swelling noted with the left cheek in the submandibular region. The swelling was diffuse, extending supero-inferiorly from 2 cm below the ala tragus line up to the lower border of the mandible on the left side and anteroposteriorly from 1 cm posterior to the left corner of the mouth up to 1 cm anterior to the left angle of the mandible. The size was roughly 2 × 2 cm. On palpation, it was firm to hard in consistency, fixed/adhering to the underlying structure and non-tender. Mouth opening was two fingers [Figure 1].

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Figure 1:

Pre-operative clinical image (extraoral).

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Intraorally, an ulcero-infiltrative lesion was noted over the left mandibular alveolus region extending anteroposteriorly from distal to 36 to the retromolar region and supero-inferiorly from the crest of alveolus to gingivobuccal sulcus. The size was approximately 3 cm × 1 cm with irregular borders, rough surface, everted edges, and erythematous appearance. On palpation, the lesion was tender; induration was present with bleeding on provocation. Blanching was noted over buccal mucosa bilaterally and over hard and soft palate. Uvula was shrunken. Tongue movements were restricted up to the vermilion border of lower lip. Homogenous melanotic patches were noted over the buccal mucosa and lateral border of tongue bilaterally [Figure 2].

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Figure 2:

Intraoral pre-operative clinical image. Arrow shows the ulcero-proliferative lesion over left mandibular alveolus.

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Investigations performed included incisional wedge biopsy from the left mandibular alveolar region. Histopathology report was suggestive of moderately differentiated SCC. Contrast-enhanced computed tomography scans revealed an ill-defined heterogeneously enhancing lesion of the left mandibular alveolus with erosion of underlying mandibular bone. Fat planes were normal with non-invasion of the muscle planes. Few sub-centimetric enhancing lymph nodes were noted at Levels 1A, 1B, and 2A.

Surgical procedure

Under all aseptic precautions, the patient was posted for surgery – Hemi-mandibulectomy + modified radical neck dissection + followed by reconstruction using PMMC flap under general anesthesia. Intubation was done nasally from the left side. The patient was scrubbed using 7.5% povidone iodine scrub and painted with 10% povidone iodine solution. Draping was done.

An angle split Schobinger incision was marked with cross-hatch over left side of the lower jaw and neck and locally infiltrated with 2% lignocaine hydrochloride with 1:2,00,000 adrenaline [Figure 3].

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Figure 3:

Marking of angle split Schobinger incision.

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The incision was given using a surgical blade no 15. Then, dissection was done along the subplatysmal plane. The greater auricular nerve and external jugular vein and the marginal mandibular nerve were identified and preserved; the platysma muscle flap was raised. The dissection was continued till the inferior belly of the omohyoid. Then, the dissection was carried toward the anterior belly of the digastric muscle. At lower border of mandible, facial artery and vein were identified, cut, and ligated. Then, the Level IA lymph region fibrofatty tissue was identified and excised between the two anterior bellies of the digastric. The sternocleidomastoid muscle was identified; the sternal head was cut till the superior belly of the omohyoid muscle to separate it from the underlying internal jugular vein (IJV). The Erb’s point was noted followed by identification of the spinal accessory nerve (SAN) 1 cm superior to this point. SAN was preserved. The dissection was continued to visualize the IJV and ansa cervicalis, up to the supraclavicular region. The Level V lymph node with fibrofatty tissue was identified and excised. Then, the inferior belly of omohyoid was identified and dissection was carried out at the Level IV. Then, Level IV lymph node with fibrofatty tissue was identified and removed, followed by dissection superiorly to identify and excise Level III fibrofatty tissue. Superiorly, the posterior belly of digastric was identified along with the SAN. Then, the Levels IIA and IIB lymph node was identified and excised. Dissection was carried out medially at the Level of IB lymph node while preserving the hypoglossal nerve and branches of the facial artery and veins.

Then intraorally, wide local excision of the primary tumor was done, keeping an adequate soft-tissue mucosal margin over the tumor using electrocautery [Figure 4].

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Figure 4:

Resected primary tumor specimen.

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The cheek flap was raised until coronoid process was identified and dissection was continued posteriorly toward the left condyle. The parotid duct was also identified, cut, and ligated to prevent sialocele formation. Then, the fibers of the lateral pterygoid muscle were excised from the neck of the left mandibular condyle. The branch of the internal maxillary artery was identified, cut, and ligated. Medially, the dissection was continued and the lingual nerve was identified and spared. For hemi-mandibulectomy, the anterior cut is given using a Gigli saw from distal to the canine tooth. Superiorly, cut was given at the maxillary lateral incisor tooth to last molar + retromolar trigone region. Posteriorly, the condyle was freed from the pterygoid and temporalis muscle and specimen was delivered and all margins were rechecked for close margin [Figure 5]. Hemostasis was achieved, copious irrigation was done using Betadine + Normal saline solution. Chyle leak was checked.

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Figure 5:

Intraoperative image after neck dissection and segmental resection of mandible.

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Then marking was done for PMMC flap over left chest. The first line was drawn from the acromion process of the clavicle to the xiphisternum. The clavicle was marked. Then, a second line was drawn perpendicular to the first-line starting from midpoint of the clavicle. The intersection of these two lines determined the superior end of the skin paddle. Skin paddle was marked of size 9 cm × 9 cm and a curvilinear incision was marked lateral to the paddle marking, toward the axilla and locally infiltrated with 2% lignocaine hydrochloride with 1:2,00,000 adrenaline solution [Figure 6].

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Figure 6:

Marking of pectoralis major myocutaneous flap.

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Incision was given using surgical blade no. 22 till below the level of the deltopectoral fascia. Leaving adequate subcutaneous tissue and fat along the skin paddle, tuck-in sutures using Vicryl 2-0 were placed from the skin paddle to the pectoralis muscle. Dissection was continued along the plane between the pectoralis major and pectoralis minor muscles and toward the clavicular region [Figure 7]. The thoracoacromial vessels (pedicle) were identified and dissection was carefully done preserving the pedicle [Figure 8].

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Figure 7:

Incision of pectoralis major myocutaneous flap. Note the skin paddle with tuck-in sutures to prevent it from shearing from underlying pectoralis major muscle.

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Figure 8:

Thoraco-acromion vessels identified – pedicle of pectoralis major myocutaneous flap (arrow) preserved before tunneling.

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The pectoral nerves were identified and cut. The dissection toward the tunnel was done such that it was four fingers wide, and then, the PMMC flap was tunneled into the neck with careful preservation of the vascular pedicle. This was followed by insetting of the flap over the defect and the flap was sutured using Vicryl (2-0) with horizontal mattress technique [Figure 9].

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Figure 9:

Tunneling of pectoralis major myocutaneous flap and insetting of the flap into the defect.

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Closed drains were placed in the neck and in the chest followed by layer-wise closure using Vicryl (3-0), Vicryl (2-0), and Ethilon (3-0) sutures and surgical stapler. Dressing was given. Post-operative histopathology report was suggestive of moderately differentiated squamous carcinoma involving left buccal mucosa, lower gingiva and retromolar trigone, and lower alveolus with Level IIa nodal metastasis with perinodal extension. The patient was followed up for 3 months initially and showed good uptake of the flap. There was adequate mucosalization of the flap and patient showed signs of recovery with no adverse outcomes [Figure 10].

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Figure 10:

Flap site (3-month follow-up).

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DISCUSSION

The procedure for harvesting free flaps is complex, time-consuming, and demands specialized training and infrastructure, making it unworkable in all settings. As a result, alternative reconstructive techniques using local and pedicled flaps have been widely adopted in many high-volume cancer centers to achieve optimal outcomes.^[15] Although Ariyan described PMMC flap as the work horse flap in head-and-neck reconstruction long ago,^[16] its significance remains undeniable despite the widespread use of free flaps over the past decade.^[17-19] This is due to the flap’s easy harvestability and the ample availability of both skin and soft tissue, making it highly effective for reconstructing large defects in the oral cavity. Due to its close proximity to the primary tumor site and a well-defined vascular pedicle, the PMMC flap serves as a reliable pedicled flap for head-and-neck malignancies. Its bulkiness makes it particularly suitable for advanced oral cancers, where extensive tissue transfer is required for defect reconstruction.^[20-23] PMMC flap is a versatile, robust flap as far as survival is concerned. Harvest of the flap is technically easy, quick, and economical. It has good vascularity, adequate bulk, and can cover extensive defects.^[24]

In a study by Bowe et al.^[25] involving 30 consecutive patients who underwent lateral segmental mandibulectomy with a bridging reconstruction plate and an anterolateral thigh flap, a chimeric flap with a muscle component was used to eliminate dead space between the skin and plate. This approach resulted in plate extrusion in only 2 patients (6.7%). These factors led to the popularity of free flaps. The free fibula flap remains the preferred choice for reconstructing segmental mandibular resection with or without continuity defects. However, its drawbacks include prolonged surgical duration, limited soft-tissue volume, and an inadequate skin paddle for extensive defects.^[12]

In contrast to free flap surgery, which typically exceeds 9 h, our technique had a surgical time of 5 h and 30 min. In addition, this approach offers benefits such as shorter hospital stays, faster recovery, and minimal donor site morbidity. Although osteocutaneous free flaps are considered a superior option for mandibular defect reconstruction, their use is limited in elderly patients with significant comorbidities, as these factors may lead to a lower graft uptake rate.

Compared to free flaps, PMMC reconstruction is simpler, easier to harvest, and does not require a specialized microvascular team, making it a popular choice for head and neck reconstruction. However, it is not without drawbacks, including difficulties in articulation and excessive bulkiness, which can prevent complete jaw occlusion. While most patients experience some degree of articulation impairment postoperatively, this issue significantly improves after radiotherapy (RT) due to muscle atrophy. The substantial volume of the PMMC flap helps maintain cheek contour and esthetics, even after radiation therapy. A potential postoperative concern is hair growth in the oral cavity, though mucosalization typically occurs over time in most patients.^[26] Total loss of the PMMC flap is rare. Partial necrosis of the PMMC flap has been reported as 6.6–32%.^[4]

Post-surgical resection of the primary tumor, another important aspect of the treatment plan is to histopathological examination on which further determines the need for RT or chemotherapy (CT). The important parameters which decide the requirement of adjuvant therapy include the following:

1. Type of tumor-most oral malignancies are SCCs or its variants, well, moderate to poorly differentiated. In this case, it was a moderately differentiated SCC

2. Status of all margins after tumor resection-A minimum of 5 mm clear margin may be considered ideal. In our case, the closest cut margin was 1 cm which was more than adequate

3. Stromal response: Whether it is lymphoplasmacytic or desmoplastic stroma which is evaluated. In the present case, dense lymphoplasmacytic inflammatory infiltrate was noted

4. The presence or absence of lymphovascular emboli indicates that cancer cells (tumor emboli) have been detected within the lymphatic and/or blood vessels of a tumor or tissue. This suggests that the cancer has gained access to the body’s circulatory and lymphatic systems, increasing the potential for it to spread to other areas of the body; in this case, lymphovascular emboli are not seen

5. Whether there is perineural invasion (PNI) present or absent: PNI in oral cancer describes the spread of cancer cells along the nerves within the oral cavity. It is considered an important indicator of poor prognosis, as it is associated with more aggressive tumor behavior, a higher likelihood of recurrence, and decreased survival rates. In our case, no PNI was noted

6. To evaluate involvement of underlying bone-histopathologically, the underlying bone was not free of tumor in this case. However, the pathologist has not specified the extent of bony erosion, whether it involves periosteum, cortex, and/or medulla. Involvement of bone/erosion upstage the disease to T4 stage, which again poor prognostic factor of patient survival

7. Involvement of overlying skin is assessed as involvement of skin also upstages the disease to T4 stage, which again poor prognostic factor of patient survival. In this case, overlying skin was free of tumor

8. Neck node status is also an important factor, it includes-

   1. Number of total nodes dissected-A total of 42 lymph nodes were dissected in this case. An adequate neck dissection typically involves the removal of 18–36 lymph nodes, although the exact number can vary depending on the levels involved (e.g., Levels I–III, IV, or V)

   2. Number of nodes showing metastasis was 1 lymph node

   3. Perinodal extension present or absent-In this case, it was present, which is a key prognostic factor in oral cancer, associated with a more aggressive disease course and lower survival rates. Its presence indicates that cancer cells have penetrated the lymphatic system, increasing the likelihood of distant metastasis.

On these above findings of histopathology report (HPR), we stage the disease as per TNM classification, our case was a pT4N1M0 stage.

General indications for post-operative RT (PORT) include: Large T3 or T4 primary tumor; high grade or infiltrative tumor, compromised surgical resection margins (<5 mm from the inked surface of the specimen); presence of lymphovascular invasion and/or PNI; and positive lymph nodes-bulky nodal disease (N2/N3), multimodal involvement, and presence of extra-nodal extension.^[27]

Chemo-RT is added when there is a positive or close margin after curative resection or presence of nodes with perinodal extension. Margins of 1.5–2 cm or more are typically classified as adequate, those >0.5 cm are considered clear and <0.5 cm are considered close margins.^[15]

In this case, there was perinodal extension which was present that patient was advices concomitant CT+RT. Because adding chemo make cancer cells more radiosensitive and increase the efficacy of RT which give chance for curative intent and survival.

Follow-up protocol for such patients is every 2–3 months in first 2 years, 6 monthly for next 3 years and annually thereafter. On every follow-up thorough head-and-neck examination for loco-regional control, second primary tumor and late sequelae of treatment is evaluated. Investigations are performed only if indicated by symptoms and positive clinical findings. Serum T3, T4, and thyroid-stimulating hormone are advised annually for all patients receiving PORT.

CONCLUSION

The pedicled PMMC flap is a strong, reliable, and versatile reconstructive option. It is well-suited for reconstructing extensive gingivobuccal complex defects, offering acceptable cosmetic and functional outcomes.