Ectopic salivary tissue of the mandibular condyle: A case report and review of the literature

Abstract

Primary ectopic salivary tissue within the mandible (salivary choristoma) is a rare phenomenon. Previous cases of mandibular intraosseous salivary tissue usually arise due to salivary gland tissue perforation through the lingual cortical plate in the posterior body/angle region of the mandible. We present a case report of a 22-year-old, otherwise healthy, woman who presented with an asymptomatic radiolucent lesion of the left condylar neck and head. The pathology was discovered on routine radiographs. A surgical approach utilizing a vertical ramus osteotomy through a submandibular incision was utilized to explant the condyle with a ramus segment. An extracorporeal removal of the pathology was performed and the defect was grafted prior to reimplantation of the segment which was stabilized with bone plates and screws. Histopathologic analysis revealed ectopic salivary tissue consistent with an intraosseous salivary gland choristoma. This report will discuss clinical findings, surgical intervention, and potential mechanisms to explain the etiology of ectopic salivary tissue within the mandible.

Highlights

  • Historically, salivary tissue growth within bones of the head and neck is rare.

  • Asymptomatic growth found within mandibular condyle.

  • Lesion removed via extraoral vertical ramus osteotomy.

  • Biopsy of condylar lesion resulted in benign salivary tissue.

Introduction

Ectopic salivary gland tissue has been documented in multiple locations within the head and neck region, including the middle ear, cervical lymph nodes, mastoid bone, skin of the neck, as well as various regions within the mandible [ ]. While considered rare, the prevalence of salivary tissue in the mandible has increased since being highlighted by Dr. Stafne in 1942 [ ]. Stafne defects are diagnosed radiographically, as a well-defined, round, unilocular radiolucency located below the mandibular canal between the first molar and angle of the mandible. The defect arises secondary to pressure from the submandibular gland, thinning or even eroding through the adjacent lingual cortical plate. However, without direct clinical observation, the pathogenesis of the cortical erosion is unclear. When discovered in other less common areas, like the anterior mandible, exploration of these lesions reveal solid tissue pedicled to the lingual soft tissues through a defect in the lingual cortex. Histologically, the lesions reveal salivary tissue [ ]. Intraosseous ectopic salivary tissue is rare and only one report of histologically confirmed benign salivary gland tissue in the condylar region has been documented in the literature [ ]. We provide an example of an unusual presentation of ectopic salivery tissue exhibited in the mandibular condyle.

Case report

A, 22 year old otherwise healthy female with no related past medical history was referred for evaluation of an asymptomatic radiolucent lesion of the left mandibular condyle and neck incidentally discovered with a panoramic radiograph. The panoramic radiographs from her orthodontist demonstrated the presence of the lesion throughout orthodontic treatment which was initiated at age 12 ( Fig. 1 ). A CT scan revealed a 3 × 1.3 × 1.3 cm hypoattenuating intramedullary mass within the left mandibular ramus and condyle ( Fig. 2 ). No cortical disruption or expansion was identified, although thinning of the cortex was present.

Fig. 1
Serial panoramic radiographs from pre and post treatment. A) Initial orthodontic treatment with evidence of lesion of the left condyle. B) Completion of orthodontic treatment C) Initial presentation to UNC. D) 1.5 months post-surgery. E) 1 year follow up.

Fig. 2
CT Maxillofacial exhibiting a well circumscribed radiolucent lesion of the left mandibular ramus and condylar neck extending into the condyle. No evidence of erosion through the cortex.

Given the benign appearance of the lesion, pending wedding ceremony, and the challenging anatomic location, a decision was made to forego an incisional biopsy and perform excision of the lesion. The patient underwent a left vertical ramus osteotomy via a submandibular approach to amputate the condyle along with a segment of the ramus to allow for complete removal of the lesion extracorporeally. During removal of the condyle, there was a fracture of the mid-ramus due to the thinning of the cortex as well as perforation of the medial cortex of the condylar neck. The lesion was curetted from the specimen and sent for histopathology ( Fig. 3 ). On inspection, the tissue was solid with no cystic components.

Fig. 3
Surgical specimen: A) Vertical Ramus osteotomy with condyle and posterior ramus. B) Fracture of the segment visualized with subsequent fixation.

Following removal of the lesion, the bony cavity was packed with allogeneic bone mixed with bone morphogenic protein after being reconstructed/reinforced with titanium plates. The proximal condyle was then re-implanted into the glenoid fossa and secured with titanium plates to the distal segment of the mandible. This restored her preoperative position and occlusion. Immobilization was not instituted but range of movement was controlled with Erich arch bars with elastic traction.

The patient was discharged home and placed on a soft diet for 6 weeks. Post-surgical radiographs confirmed an adequate position of the treated mandibular condyle. The specimen was read as “benign salivary gland tissue, adipose, fibrous tissue, focal skeletal muscle, reactive lymph tissue, and scant benign bone. Negative for evidence of malignancy or odontogenic tumor.” An additional comment stated “intraosseous heterotopic salivary gland tissue could represent a salivary gland choristoma.” The case was subsequently reviewed independently by a Board Certified Oral and Maxillofacial Pathologist who agreed with the diagnosis of salivary gland choristoma ( Fig. 4 ).

Mar 21, 2021 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Ectopic salivary tissue of the mandibular condyle: A case report and review of the literature
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