1Division of Plastic Surgery, Department of Surgery, School of Medicine, University of Mississippi Medical Center, Mississippi, USA
2Department of Oral Maxillofacial Surgery and Pathology, School of Dentistry, University of Mississippi Medical Center, Jackson, Mississippi, USA
*Corresponding author: Abelardo Medina, Assistant Professor of Surgery, Division of Plastic Surgery - Department of Surgery, University of Mississippi Medical Center, 2500 North State Street, Jackson, Mississippi 39216, USA
Received Date: 29 December, 2020; Accepted Date: 22 January, 2021; Published Date: 26 January, 2021
Maxillary ameloblastomas are rare odontogenic epithelial tumors predominantly located in the posterior segment of the maxilla. Due to their anatomical confinement and difficulties for successful resection, these tumors show high risk of postoperative complications and recurrence. The reconstruction with vascularized bone grafts appears to be a reasonable option for optimal cosmetic and functional results. We present a case of maxillary ameloblastoma located at molar region treated with extensive resection and scapular tip free flap.
Maxillary ameloblastoma; Maxillectomy; Radical resection; Spular tip free flap
Ameloblastomas are benign, but locally invasive tumors originated from remnants of dental lamina, enamel organ and odontogenic epithelium . They are responsible for 1% of all tumors and cysts of the jaws and 10% of odontogenic tumors [1-3]. They are mainly seen in adults with male predilection and more frequently located in the mandible . Ameloblastomas are classified into four different categories namely multicystic, unicystic, desmoplastic and peripheral . Even though conservative approaches have been described (i.e., enucleation, curettage), extensive surgical excision seems to be the only modality of treatment that secure reasonable curative rate [2,6]. Ameloblastomas can experience locoregional recurrence, develop distant metastasis and even malignant transformation [7-9].
Maxillary ameloblastomas are mostly located in the molar region and frequently progress into adjacent tissues and anatomical spaces [10,11]. The diagnosis is established with the clinical examination, radiologic appearance and histological findings. Maxillary ameloblastomas may exhibit minimal or no symptoms at the time of the diagnosis . However, they are able to develop toothache, loose teeth, intraoral ulceration, edema or nasal obstruction, nasal epistaxis and visual disturbances. In general, symptoms appear when the lesion has already advanced beyond the maxillary bony boundaries . In imaging tests, maxillary ameloblastomas display unilocular or multilocular radiolucency features associated with destruction of cortical bony walls . They can present different histopathologic patterns, but follicular is the more frequent variant .
A 54-year-old African American male who presented to our clinic after dental extraction of impacted tooth #1 and biopsy that revealed right posterior maxillary ameloblastoma. Patient denied weight loss, pain, loose teeth, dysphagia, sensory deficit, facial edema, sinus congestion or discharge. His past medical history included controlled hypertension and abdominal surgeries (appendectomy, small bowel obstruction). No history of tobacco or alcohol consumption.
On physical examination, his neck appeared symmetric with normal range of motion, soft, non-tender and with no palpable lymphadenopathies. Normal temporomandibular joints assessment and good dentition with stable and reproducible occlusion. Maximum Interincisal Opening (MIO) of 40-mm. Normal intraoral soft tissue appearance with well healed socket from previous extraction and no obvious exophytic mass or expansion of bone in maxilla. Panoramic dental radiograph and CT neck demonstrated a 2.8 x 2.4 x 1.5 cm expansile lesion centered in the posterolateral aspect of the right alveolar maxilla (Figure 1). Other findings were unremarkable except impacted tooth #16 and unerupted tooth #32. The chest imaging assessment was normal except for thoracic scoliosis. CTA of lower extremities showed that posterior tibial arteries were diffusely small in caliber and peroneal arteries provided blood supply to plantar regions. CTA of chest revealed a favorable vascular anatomy for a right scapula flap. The presence of circumflex scapular artery and angular branch of thoracodorsal artery were confirmed with handheld Doppler. Based on patient’s body composition (BMI 22 kg/m2) and Doppler findings, we decided to perform an ipsilateral Scapular Tip Free Flap (STFF). Prior to the surgery, a virtual surgical planning session was carried out to design a pre-bent plate and surgical cutting guides for both maxillary and scapular resection (Figure 2(A-B)).
Patient underwent general anesthesia with endotracheal intubation through the left nostril. To maintain the same position during the entire procedure, the patient was placed in a modified lateral decubitus at 30 degrees of right hip elevation and 45 degrees of chest rotation (Figure 2C). This position was achieved with foam padding and suction beanbag. The opposite upper extremity was cradled without pressure or distraction on the shoulder. In addition, adequate padding was applied around knees, ankles and feet. During the surgery, we modified the lateral inclination of the operating table every 1-2 hours to change the points of maximum pressure on the skin. The right upper extremity was prepped and covered with sterile sleeve to facilitate its movements and the dissection within the surgical field. A sterile handheld Doppler was utilized to localize and define trajectory of vessels of interest, and subsequently, confirm the integrity of the resulting flap pedicle. An incision on the right neck was performed (2-cm below the mandibular margin) by the ablative team to expose neck vessels in preparation for microanastomoses. Using intraoral approach, and after appropriate elevation of soft tissues, a right partial maxillectomy was initiated with reciprocating saw over prefabricated cutting guides. Then, through a series of straight and curved osteotomes, the specimen was finally freed and passed off to the back table.
Simultaneously, the reconstructive team started the elevation of the right STFF. A lazy S incision was made along the mid-axillary line ending in the inferior angle of the scapula (dotted green line, (Figure 2C)). Superior and inferior skin flaps were elevated above the muscular plane. Thereafter, the superior border and the inner aspect of the latissimus dorsi muscle were dissected to expose the scapula tip and identify the angular branch (Figure 3A). To facilitate the isolation of the flap and its pedicle in cephalad direction, the teres major and rhomboid muscles were divided with Harmonic scalpel. The subperiosteal branch of the circumflex scapular artery was also identified and dissected in cephalad direction (Figure 3A). These two scapular pedicles were fully freed from surrounding tissues in retrograde direction until they converged into a main pedicle (12 cm in length) formed by the subscapular artery and a large accompanying vein. Subsequently, using prefabricated cutting guides and oscillating saw, we performed the bony cuts to obtain the vascularized STFF (Figure 3B). A nonvascularized bony segment was also obtained from the lateral border of the scapula (Figure 2A). Subsequently, under the microscope, end-to-end arterial anastomosis with right facial artery (2.5 mm in diameter) and end-to-side venous anastomosis with right external jugular vein were performed using interrupted stitches of 8-0 nylon and 3.5 mm coupler, respectively.
After completion the microvascular step, the flap was inset using the prefabricated plate and monocortical screws (Figure 4A). In addition, as planned, the nonvascularized bone graft was utilized to reconstruct the remaining maxillary-zygomatic defect. This was fixed in position with a separate straight plate and monocortical screws. Next, the oral cavity and neck were profusely irrigated with normal saline and closed in standard fashion. At the right scapular region, the surgical field was also irrigated and hemostasis achieved with bipolar electrocautery. To prevent winged scapula, several holes were drilled through the scapula near to the new postosteotomy lateral edge. These bony holes were used to reattach previously divided teres major muscle with several stitches of #0 PDS. Two 19 Fr Blake drains were placed inside the surgical cavity, exited through the skin and secured with 3-0 nylon stitches. The incision was finally closed by layers using multiple stitches of 2-0 and 3-0 PDS. The skin closure was accomplished with interrupted stitches of 3-0 nylon. At the end of the case, the patient was transferred to surgical intensive care unit in stable condition. The patient stayed intubated, sedated and in respiratory support until the following morning. The immediate postoperative period was satisfactory without any complications. The histopathologic examination of the specimen reported unicystic (2.9 x 1.4 x 1.1 cm) ameloblastoma with mural invasion. All margins were negative for tumor. Patient was discharged on day 6 after surgery with arm sling to limit Range of Motion (ROM) of the right shoulder. The active ROM of the shoulder was initiated on postoperative day 11 and weight bearing exercises 7 weeks after surgery. Three weeks after surgery, the flap required bulking procedure in clinic due to redundant intraoral soft tissue that was interfering with occlusion (Figure 4(B-C)).
Fourteen months after surgery, patient has no signs of local or systemic recurrence. He reached a satisfactory outcome, working without restrictions with no local pain or edema, inconspicuous scar on the neck, symmetric face, normal MOI and adequate bony structure and intraoral lining for dental implants (Figure 4(CF)). The donor site of the flap exhibited soft, pliable and painless mature scar. The right upper extremity displayed normal ROM and strength without pain (Figure 5). Patient verbalized to experience only sporadic tingling on the right arm that does not affect his activities of daily living (DASH score of 0.8/100).
Currently, the reconstruction of head and neck tumors needs to consider not only the repair of ablative defects, but also meet expectations of optimal functional and cosmetic outcomes with short hospital stay and minimal complications and residual morbidities. In general, the curative management of ameloblastomas should include the complete excision of the tumor with a 1-1.5-cm safety margin of uninvolved bone around the lesion. This radical approach is often necessary because the definitive diagnosis (including microscopic extension) is only possible after histological examination of the entire specimen [3,16].
The incidence of maxillary ameloblastomas is lower (15%) than their mandibular counterparts [13,14]. However, due to the cancellous nature of the bony structure at their more frequent location (molar region), maxillary ameloblastomas tend to break the “Eggshell-Like” thin cortical bone and subsequently invade adjacent anatomical spaces. For instance, they can spread into pterygomaxillary space, nasal cavity, paranasal sinuses, infratemporal fossa and orbital cavity. Furthermore, maxillary ameloblastomas can infiltrate the skull base, and even the central nervous system which account for most of fatal cases of this condition [12-14]. Accordingly, radical resection of any maxillary ameloblastoma (i.e., partial/total maxillectomy, en bloc resection) seems to be necessary to ensure local control of the disease. However, the deep anatomical confinement of these lesions and proximity of vital structures may cause highly challenging resections and often insufficient safety margins . For this reason, maxillary ameloblastomas present elevated postoperative complications as well as significantly higher local and distant recurrence rate . Indeed, radical tumor resection in these areas generate secondary defects that require complex reconstructive procedures. Thus, immediate reconstruction with vascularized bone grafts have acquired popularity among surgeons due to psychosocial benefits of one-stage surgeries and the advantage of performing microsurgical procedures in absence of tissue fibrosis or scar contracture. This approach not only restore the bone structure, but also favors early intervention on functional aspects of the surgical reconstruction such as speech, deglutition, mastication and dental rehabilitation.
In this regard, even though it is not usually the first choice for maxillary reconstruction, Scapular Tip Free Flaps (STFF) have multiple advantages such as reliable vascular anatomy, long pedicle, several chimeric options and low rate of donor site morbidity. Their versatility makes these flaps suitable for a large variety of surgical settings. Furthermore, the muscular component (cuff of teres major muscle) can be mucosalized in few weeks and provide adherent mucosa lining on the alveolar ridge for dental implants placement. Accordingly, our patient got an uneventful surgery and short hospital stay with a satisfactory long-term cosmetic and functional outcome without major complications. He recovered full ROM and strength of the right upper extremity and returned to work in the same position as prior to the surgery and without restrictions. He is currently in the process of oral rehabilitation pursuing the placement of dental implants. After 14 months postsurgery, our patient is free of local or systemic recurrence [1,7]. Because of relapses mainly occur within the first 5 years after the primary surgery, we are planning to continue regular follow-up with this patient for at least 4 more years.
The anatomical confinement and easy spread to surrounding tissues make difficult the successful resection of maxillary ameloblastomas and increase the risks of postoperative complications and recurrence. Therefore, an experienced multidisciplinary team is required to ensure appropriate outcomes not only from ablative and reconstructive points of view, but also from the functional and psychological aspects of these cases. Reconstructive procedures for maxillary ameloblastomas with vascularized bone grafts such as fibula free flap and STFF have demonstrated excellent cosmetic and functional results.
The authors declare that there is no conflict of interest.