Incidentally discovered lacunar image of the mandible: A diagnostic orientation.

Stafne bone cavity belongs to the class of pseudocysts as a mandibular radiolucency image with well-defined borders. It is asymptomatic and incidentally discovered. CT scan is the best examination to identify characteristics and content of this image. This study aimed to highlight these radiological features to establish the correct diagnosis.

A 62‐year‐old female patient presented with right mandibular pain related to the right first molar (46). Panoramic radiography revealed a well‐limited lacunar image with a clear peripheral condensation border, located below the mandibular canal that was incidentally detected (Figure 1A). At this stage, several diagnoses were possible, including keratocyst, ameloblastoma, and Stafne lacuna. A second‐line mandibular computed tomography examination was performed. It showed a well‐limited osteolysis involving both the spongious and the lingual cortical bone. The vestibular table was reduced without rupture (Figure 1B). The mandibular canal was located below and medially to this osteolysis (Figure 1B,C), extending to the mandibular basilar border (Figure 1C,D). Narrow window sections with contrast injection revealed the presence of grease density tissue within the osteolysis, centered by tissue of glandular nature in communication with the submandibular gland (Figure 1E,F).

FIGURE 1

(A) Panoramic radiography: lacunar image (white arrow) related to the mandibular canal (black arrow) and extending towards the basilar border. (B) Axial CT section: destruction of the lingual cortex (white arrow), thinning of the vestibular cortex (white arrowhead). (C) Coronal CT section: osteolysis extending superiorly and laterally, leading to thinning of the vestibular cortex and to lingual displacement of the mandibular canal. (D) Sagittal CT reconstruction: evolution of osteolysis below the mandibular canal to the basilar border. (E, F) Axial CT section and oblique reconstruction perpendicular to the mandibular body in a narrow window with contrast product: osteolysis of greasy nature (star) centered by an image of glandular density (black arrowhead) and communicating with the submandibular gland (SMG) by a canal (white dotted arrows)

All these clinical and radiological features were in favor of Stafne bone cavity. It is a benign, asymptomatic, and rare bony depression of incidental finding, often found in the posterior region of the mandible. It is due to an exaggerated depression caused by hyperplastic lobe of a salivary gland and classified according to the basis of its depth and content. In the present case, this lacuna is type II according to the depth, type G depending on the content, type 5 based on the contact with the mandibular canal, and type D regarding the contact with the basilar border of the mandible. According to the literature, this class is considered among the least frequent.

AUTHOR CONTRIBUTIONS

Dr. R. K. contributed to the study design, radiographs analysis, and writing of the paper. Dr. I. C. contributed to the study design and radiographs analysis. Dr. T. B. supervised the study, contributed to radiographs analysis, and to the writing of the paper.

CONFLICT OF INTEREST

The authors declare that they have no conflict of interest.

CONSENT

A written informed consent was obtained in accordance with the journal's patient consent policy.