Answer: B. Stafne defect( SD)
Stafne defect( SD) is a normal anatomic variation. It represents a concavity in the cortical bone in the lingual mandible where a portion of a salivary gland rests, most frequently the submandibular gland. Clinically, the lesion is asymptomatic. Usually, it is thought to represent a developmental disorder that is believed to be congenital in nature, but it develops with time and presents in middle-aged to older adults. SD is not rare, and are present in 0.08 to 0.48 % of panoramic radiographs, with a striking 80-90 % male predilection. 1 Usually they are unilateral, but can present bilaterally.
Radiographically, they typically present as an asymptomatic, round to oval-shaped well-defined radiolucencies at the body or angle of the posterior mandible, often inferior to the IANC or occasionally overlapping the IANC. 2 Clinically, they present as a focal concavity or notch on the lingual surface of the mandible, but palpation of the area is difficult due to the overlap of other anatomic structures. Most commonly, 57 percent of cases present in the first molar and bicuspid area. 2 Occasionally, they have been noted to appear in other locations of major salivary glands, including the anterior mandible in association with the sublingual gland, or the ascending ramus in association with the deep tail of the parotid. 1 However, there have been cases that contained a cavity with muscle, fibrous / connective tissue, blood or lymphatic vessels, lymphoid tissue, or adipose tissue. 2 If present more anteriorly, the lesion may appear superimposed over the apices of teeth, mimicking periapical lesions. 1, 2
SD may be diagnosed on radiographic presentation, in conjunction with the clinical findings, namely, the lack of symptoms. Advanced imaging may be performed if the features on plain film imaging are not conclusive. Conventional or cone beam computed tomography imaging, magnetic resonance imaging( MRI), or even sialography can be used for diagnosis. MRI is quickly becoming the method of choice to determine the type of tissue present within the cavity, because it uses comparisons of tissues based on their soft tissue densities. 3 Biopsy is indicated if there is clinical suspicion of a pathologic lesion. Surgical exploration usually reveals normal salivary tissue in the defect. 2, 3 Since the defect represents an anatomic variation of normal, treatment is not indicated. In this case, given the presentation of asymptomatic, well-defined, bilateral radiolucencies inferior to the IANC, near the angle of the mandible in a middle-aged male, SD was considered high on the list of the differential diagnoses. No biopsy was performed in this case due to the lack of suspicion of any pathologic processes. Periodic radiographic observation is recommended.
Discussion
A. Traumatic neuroma is considered to be a reactive process rather than a neoplastic process. It forms as an exaggerated response to injury from a severed or damaged nerve bundle’ s attempt to regenerate. 4 The proximal portion of the nerve attempts to re-establish innervation to the distal portion of the nerve. In the case of trauma, scar tissue may inhibit this reinnervation, and this causes a tumor-like mass to form as the nerve continues to regenerate to establish connection. 1 TNs can occur at any site of trauma, but they are more common in the area of the mental foramen, lower lip, and tongue. 4, 5 They commonly occur after surgery or after extraction of the teeth with roots close to the inferior alveolar canal. Radiographically, these may be seen intraosseously as well, presenting as a well-delineated, radiolucency with diffuse borders that are contiguous with the inferior alveolar nerve canal or mental foramen( Figure 2). The lesions are most commonly diagnosed in middle-aged adults, but they can occur at any age and there is a slight female predilection. 4 They can present as a smooth nodule with up to one third of patients presenting with pain that can ranging from mild tenderness to severe burning, but paresthesia, anesthesia, or dysesthesia may occur. The pain is caused by compression of the nerve by the lesion itself. 4 Histologically, TNs appear as haphazard proliferations of mature nerve bundles in a fibrous stroma. It is usually a proliferation of the perineurium, epineurium, and endoneurium of the nerve as well as Schwann cells, and regenerating axons. 6 Inflammation may or may not be present. Treatment involves surgical excision of the lesion, including a small portion of the proximal nerve. The majority of lesions do not recur; however, there are reports of persistent pain and recurrence of the lesion after excision.
30 JANUARY / FEBRUARY 2017 | PENNSYLVANIA DENTAL JOURNAL