Odontogenic myxoma of maxilla: A rare presentation in an elderly female.

Odontogenic myxomas are rare benign neoplasm of mesenchymal origin, comprising 3-6% of all odontogenic tumors. They are slow growing, non-metastasizing, often asymptomatic with local aggressiveness due to its infiltrative nature and hence high recurrence rate, with a high incidence of occurrence in the mandible. Most frequently occurs in second to third decade of life, seldom occurs beyond these age groups. Hereby, we present a case of odontogenic myxoma occurring in the maxilla in a 65-year-old female managed by partial maxillectomy.

Odontogenic myxomas are benign tumors, non-metastasizing, nonencapsulated, derived from the primitive mesenchymal tissue of dental follicle, dental papilla or periodontal ligament.[1] WHO defines odontogenic myxoma as a benign, locally invasive neoplasm characterized by rounded and angular cells lying in an abundant mucoid stroma that replaces the cancellous bone expanding the cortex.[2] Clinically present as a slow-growing, locally aggressive lesion, often remains asymptomatic and hence reach considerable size even before patient become aware of it and seek treatment.[3] It more frequently affects the mandible than maxilla in the ratio of 3:1. Commonly occurs in the age group of second to a fourth decade, more often in females than in males. Rarely occurs below 10 years of age and older than 50 years.[4]

Odontogenic maxillary myxoma was first described by Thoma and Goldman in 1947, which is less frequent and behaves more aggressively than mandible, as it spreads through maxillary sinus, causing loosening and displacement of tooth and less frequently root resorption and exophthalmos and nasal obstruction in severe cases.[56]

Radiographically, it presents a varied appearance ranging from unilocular radiolucency to multilocular and mixed radiolucent-radio opaque lesion.[3] Histologically, the mucoid stroma is responsible for its local infiltrative nature, and it may resemble few malignant lesions such as myxoid chondrosarcoma and malignant nerve sheath tumor.[7] Hence, it necessitates accurate clinical, radiological, and histopathological interpretation to arrive at a definitive diagnosis and effective management of the patient.

Clinical Presentation

A 65-year-old female patient presented with a complaint of swelling over the left side of the cheek for the past 6 months. Patient gave a history of the extraction of a left back tooth due to mobility 3 months back, followed by progressive increase in the size of the lesion accompanied by a dull pain and burning sensation with difficulty in swallowing.

Extraoral examination revealed a diffuse, ill-defined, firm swelling of size 5 cm × 4 cm involving the left cheek extending superioinferiorly from infraorbital rim to 2 cm above the inferior border of the mandible. Medially the lesion was found to extend to the lateral wall of the nose with obliteration of the nasolabial groove and laterally to about 1 cm in front of tragus; the skin over the lesion appeared normal and pinchable. The swelling was tender and afebrile.

Intraoral examination revealed an erythematous ulceroproliferative growth on left maxillary alveolus extending anteroposteriorly from 23 to the left maxillary tuberosity. Medially the lesion was found to extend 1 cm lateral to midpalatine raphae and laterally extending buccally with obliteration of the vestibular sulcus. The entire occlusal surface of the left posterior teeth was covered by the lesion with an inferior extension of about 1 cm below the occlusal plane [Figure 1].

Figure 1

Ulceroproliferative growth involving left maxillary alveolus

Radiographically para nasal sinus (PNS) view of the skull shows haziness of the entire left maxillary sinus. Computed tomography (CT) scan of both axial and coronal views showed the lesion was confined to left maxillary sinus [Figures 2 and 3].

Figure 2

Computed tomography scan of coronal showing the lesion involving the left maxillary sinus

Figure 3

Computed tomography scan of axial views showing the lesion involving the left maxillary sinus

Considering the clinical and radiographic features a differential diagnosis of fibro-osseous lesion, central giant cell granuloma, ameloblastoma, and odontogenic myxoma were made. Patient was sending for a routine blood examination, which revealed normal parameters.

An incisional biopsy was performed, and the tissue was sent for histopathological examination. Microscopic examination of the hematoxylin and eosin stained tissue section showed a stroma composed of myxoid tissue with the spindle to stellate-shaped fibroblasts. Many odontogenic cell rests were present all over the stroma with loose collagen fiber bundles [Figure 4].

Figure 4

Stroma composed of myxoid tissue with spindle to stellate-shaped fibroblasts

On account of these features, the case was finally diagnosed as odontogenic myxoma. Hence, the patient was advised for surgical excision of the lesion under general anesthesia. A left side Weber Ferguson incision was placed, and partial maxillectomy was performed sparing the infraorbital rim, excising the lesion in toto, by keeping a margin of safety of 1 cm [Figure 5]. Reconstruction of the maxillary defect was done using an obturator [Figure 6]. The patient was followed up for 2 years and remained disease free.

Figure 5

Excised lesion in toto

Figure 6

Prosthetic reconstruction of the maxillary defect using obturator

Discussion

Odontogenic myxoma, an uncommon benign tumor represents 3–6% of all odontogenic tumors with a high incidence of occurrence in the mandible (66.4%) than the maxilla (33.6%).

Myxomas can occur in various sites such as skin, subcutaneous tissue, heart, and head and neck.[1] Those arising in head and neck can be either derived from facial bone (osteogenic/odontogenic) or facial soft tissues,[8] with odontogenic origin been more common. They appear to originate from the mesenchymal tissue of dental papilla, follicle or periodontal ligament. Its odontogenic origin being evident by its high incidence of occurrence in tooth-bearing areas of jaws, occurrence in young individuals, association with missing or unerupted teeth and presence of the odontogenic epithelium.[2] Controversies still persists regarding its origin as being either as a myxomatous change of odontogenic fibroma or residual foci of embryonic tissue.[29]

In 1863, Virchow coined the term myxoma for a set of tumors having a histologic resemblance to the mucinous substance of the umbilical cord.[10] In 1948, Stout redefined the histologic criteria for myxomas as true neoplasms that do not metastasize and exclude the presence of recognizable cellular components of other mesenchymal tissues such as chondroblasts, lipoblasts, and rhabdomyoblasts.

In the international histological classification of odontogenic tumors, odontogenic myxoma is defined as a benign odontogenic tumor of mesenchymal origin that is locally invasive and consists of rounded and angular cells that lie in the abundant mucoid stroma.[2]

Odontogenic myxoma commonly occurs in the age group of 10–40 years, and seldom seen below 10 years and above 50 years of age.[1011] The most frequent site of location is posterior mandible and premolar–first molar region in case of maxilla.[1112] They are often asymptomatic being diagnosed accidentally on a routine dental checkup.[12] However in advanced cases, they present with disturbing symptoms such as pain, paresthesia, mobility of teeth, ulceration, bony perforation, with subsequent invasion into the soft tissues.[1113]

Radiographically they present a varied appearance with smaller lesions tends to be unilocular, larger lesions are greater than 4 cm tend to be multilocular with a honeycomb, tennis racket or soap bubble pattern or with mixed radiopaque-radiolucent appearance.[14] CT images may present with the cortical expansion with or without cortical perforation, and a mixture of hypodense or hyperdense regions depending on the amount of calcified areas.

On magnetic resonance imaging, presents with the intermediate signal in the T1-weighted image and heterogeneous high signal on the T2-weighted image.[15] Histologically odontogenic myxoma shows proliferation of a few rounded, fusiform and stellate types of cells in an abundant myxoid stroma with scattered odontogenic epithelium and collagen fibers.

Histologically, other lesions with mucoid stroma such as neurogenic sarcoma, myxoid liposarcoma, rhabdomyosarcoma, neurofibroma, fibroma, lipoma, chondromyxoid fibroma may mimic odontogenic myxoma.[16] Clinically and radiographically odontogenic myxomas must be distinguished from cherubism, ameloblastoma, central giant cell granuloma, aneurysmal bone cyst intraosseous hemangioma, traumatic bony cyst, fibrous dysplasia, and odontogenic cysts such as radicular, lateral periodontal, dentigerous and keratocysti.[517]

On immunohistochemistry, the tumor cells show positivity for smooth muscle actin and vimentin, and negative for neuron-specific enolase, desmin, glial fibrillary acid protein and S-100, suggestive of its myofibroblastic origin.[18]

Odontogenic myxoma being benign and locally aggressive with high recurrence rate, its treatment remains controversial, varying from simple enucleation and curettage to more aggressive en bloc resection. Due to its local infiltration, simple enucleation and curettage have been associated with a high recurrence rate of 10–33% and hence requires radical excision with burring of the cavity borders with maximum preservation of surrounding structures.[12] Due to its high recurrence rate, a minimum of 5 years follow-up period is required before moving to the final reconstruction.[7] Buccal pad of fat or corticocancellous iliac crest bone graft can be used for reconstruction of maxillary bony defects lesser than 5 cm. For larger maxillary defects, greater than 5 cm requires prothetic reconstruction using obturator. For Mandibular defects, reconstruction can be done using either free fibula flap, costochondral graft, iliac crest graft or scapular osteocutaneous free flap.[19]

Conclusion

Odontogenic myxoma with its local infiltrative nature and high recurrence rate, justifies aggressive treatment with surgical en bloc resection and delayed reconstruction requiring a minimal follow-up period of 5 years to ensure disease free status before moving to final reconstruction phase. Its radiologically varied appearance and histologically the mucoid stroma mimicking few malignant lesions impose a diagnostic and operative dilemma; hence, warrants accurate clinical, radiological and histopathological interpretation to arrive at a definitive diagnosis, and effective management of patient.