Stafne bone cavity

A Stafne bone cavity is a depression in the lingual surface of the mandible, usually holding part of the submandibular gland or fat. On a panoramic radiograph it reads as a well-defined oval radiolucency in the posterior mandible, below the mandibular canal. It has no epithelial lining, so it is a pseudocyst.

Synonyms: Stafne defect; static bone cavity; lingual mandibular bone depression

What is a Stafne bone cavity?

A Stafne bone cavity is a depression in the lingual surface of the mandible [1]. The bone is hollowed from the lingual side, so the defect opens toward the tongue [2].

It has no epithelial lining. An imaging review describes it as a pseudocyst that forms as bone remodels against the submandibular gland [3]. You'll still meet "Stafne bone cyst" in paper titles. The finding is the same, and the lining is what that name gets wrong.

It is uncommon. A 2023 meta-analysis of 54 studies and 355,890 individuals put its prevalence at 0.17% (CI:0.14%-0.21%) [1]. Studies that counted it on radiographs found fewer, 0.12% (CI:0.09%-0.15%), than computed tomography, skeletal and excavation studies [1]. Single studies report anything from 0.03% to 3.55% [4].

It was four times more common in males than females in that meta-analysis, and almost always on one side only [1]. Across 465 published cases the mean age was 52.78 years [5].

Where does a Stafne bone cavity appear on a panoramic radiograph?

Follow the mandibular canal back toward the angle of the mandible. The typical cavity is an oval or round radiolucency below the canal in the posterior mandible [4, 6]. In one series of 21 patients, most sat at the angle [7].

A series of 91 cases read on panoramic radiographs described what you see most often [8]:

• a thick sclerotic margin around the whole outline
• an oval shape
• contact with the inferior border of the mandible, with the border itself unbroken
• a position level with the third molar
• a single compartment
• an interior that is only partly radiolucent

In the posterior variant, the defect most often lay below the upper wall of the mandibular canal and ran continuous with its inferior wall [8].

A systematic review of 465 published cases reported that, of the lesions with data, 93.77% were in the posterior mandible, 97.37% were unilocular and 91.97% were well-defined. The mean size was 1.58 cm [5]. An imaging review gives the usual size as under 2 cm [3]. Those figures describe cases that were written up, which is a different sample from every patient who has one.

Less common positions are reported. It can sit in the anterior mandible near the symphysis, in the ramus, or above the inferior alveolar canal, and it can be bilobate or bilateral [4, 8, 9]. Of 109 published cases gathered in one review, three were at the symphysis and six were bilateral [9].

What is inside a Stafne bone cavity?

Most contain part of the submandibular gland [2]. Multislice CT in a two-centre series showed glandular tissue within the defects [10]. In one case, MRI showed the cavity filled with soft tissue continuous with the submandibular gland and identical to it in signal [11].

Some hold only fat. In a CT study of 16 concavities, four of the six that did not reach the buccal cortical plate were filled solely with fat. Every concavity that expanded the buccal plate contained submandibular gland [12]. The published cases also report muscle, lymphoid tissue, blood vessels and connective tissue inside the cavity [9].

Whether a cavity can be empty is unsettled. The CT study found no empty concavities [12]. In an 11-case series, two of the four cavities explored surgically were described as empty [13]. Both series are small.

The cause is also unsettled. In a sialography study of seven patients, contrast filled a lobe of the submandibular gland inside the defect with certainty in two [14]. A 2025 systematic review states that the aetiology and pathogenesis are still unknown [4].

In the MRI case above, the panoramic radiograph and CT gave the outline and three-dimensional shape but could not identify the soft tissue inside [11].

How do you tell a Stafne bone cavity from a cyst?

Start with where the radiolucency sits and what it has to do with the teeth. In the 91-case series, the Stafne bone cavity most often touched the inferior border of the mandible [8].

The patient helps too. Odontogenic keratocysts occur mainly in the second and third decades, in the posterior body or ramus of the mandible, and can expand it [3]. In a series of 100 keratocysts, 47% were associated with an impacted tooth [17]. Most simple bone cysts occur before the age of 20 [3]; in a series of 23, patients ranged from 8 to 59 years, with a mean of 21.4 [18].

In a series of 64, 46.8% of patients were above 50 years of age, 60.9% were edentulous, and the posterior mandible was the commonest site (51.6%) [15]. A residual cyst sits at an extraction site, and there is always a missing tooth [3].

In a study of 500 patients, the submandibular fossa showed as a radiolucent area in 31.9% of hemi-mandibles, and whether it showed did not correlate with its depth on CBCT [16].

A simple bone cyst shares the Stafne bone cavity's lack of epithelial lining; it is filled with serous or haemorrhagic fluid [3].

Does a Stafne bone cavity need further imaging?

Authors disagree on how much imaging a typical cavity needs.

One imaging review holds that a panoramic radiograph is sufficient for diagnosis, with CT or MRI used occasionally for an atypical presentation to exclude an ameloblastoma or a traumatic bone cyst [3]. A 21-patient series prefers cross-sectional imaging to plain projections [7]. A panoramic series of 14,005 views advises excluding other pathology and notes that surgery might be necessary in doubtful cases [19]. A diagnostic algorithm from a Zurich series names odontogenic keratocyst, ameloblastoma and metastasis among the diagnoses to exclude [2].

The European SEDENTEXCT guidelines on cone beam CT set the general rules [20]:

• CBCT is used only when lower-dose conventional radiography cannot answer the question.
• Where the soft tissue needs assessing, the appropriate imaging is medical CT or MR rather than CBCT.
• For a bony lesion you are referring on, the guideline panel judged it probably correct to leave the choice of imaging to the surgeon who will treat the patient.

The Zurich series finds CBCT helpful to verify the lingual opening in atypical presentations, and MRI able to confirm the diagnosis when it is still unclear [2]. In one anterior cavity, MRI confirmed fat and avoided surgical exploration [6]. A two-centre series suggests CBCT as the non-invasive choice for the bony outline because its dose is lower than multislice CT [10].

Most cavities stay the same size. None of 11 in one series showed progressive change [13]. Enlargement has been documented, though: one case report found five similar cases in the literature besides its own [21]. A 2025 systematic review recommends periodic radiographs, noting that in exceptional cases tumours seem to have developed in the gland tissue inside the cavity [4]. One imaging review suggests a follow-up examination at 3 to 6 months can be performed to ascertain lesion stability [3].

Common errors

• Calling it a cyst. It has no epithelial lining [3]. Call it a Stafne bone cavity, or a static bone cavity.
• Assuming the dark area is gland. Some cavities hold only fat [12], and in one case the panoramic radiograph and CT could not identify the soft tissue inside [11].
• Taking "static" literally. Most do not change, and a handful have enlarged [13, 21].
• Reading position alone when the picture is atypical. A Zurich series names keratocyst, ameloblastoma and metastasis among the diagnoses to exclude [2].