Schwannoma of the external auditory canal as a part of schwannomatosis

Figures & data

Figure 1. Tumors of the external auditory canal and auricle. (a, b)At the initial visit, a painless mass with a smooth surface was found in the right external auditory canal which was almost completely occluded. Also, several tender masses with severe pain were observed around the right auricle. (a) Inside the right ear. (b) Behind the right ear. (c, d) Three years after surgery, no recurrence is observed either in the ear or the subcutaneous region behind the ear. (c) Inside the right ear (after surgery). (d) Behind the right ear (after surgery).

Figure 2. Pure tone audiometry. (a) Before surgery, conductive hearing loss of the right ear was observed. (b) After surgery, the right air-bone gap completely disappeared.

Figure 3. Preoperative images. (a, b, c, d) In CT, a 2 cm tumor on the anterior wall of the right external auditory canal with the destruction of the bones of the anterior and inferior walls was found. Also, multiple masses were observed behind the right ear. (e, f) In contrast-enhanced MRI, a tumorous lesion with a diameter of 19 mm in the right external ear canal, as well as multiple well-defined masses above, behind, and below the right auricle were found. Also, a suspected small vestibular schwannoma localized in the left internal ear canal was observed.

Table 1. Diagnostic criteria of Schwannomatosis.

Molecular diagnosis

Two or more pathologically proved schwannomas or meningiomas AND genetic studies of at least two tumors with loss of heterozygosity (LOH) for chromosome 22 and two different ‘NF2’ mutations; if there is a common ‘SMARCB1’ mutation, this defines SMARCB1‐associated Schwannomatosis

One pathologically proved schwannoma or meningioma AND germline SMARCB1pathogenic mutation

Clinical diagnosis

Two or more non‐intradermal schwannomas, one with pathological confirmation, including no bilateral vestibular schwannoma by high‐quality MRI (detailed study of internal auditory canal with slices no more than 3 mm thick). Recognize that some mosaic NF2 patients will be included in this diagnosis at a young age and that some schwannomatosis patients have been reported to have unilateral vestibular schwannomas or multiple meningiomas.

One pathologically confirmed schwannoma or intracranial meningioma AND affected first‐degree relative

Consider as possible diagnosis if there are two or more non‐intradermal tumors but none has been pathologically proven to be a schwannoma; the occurrence of chronic pain in association with the tumor(s) increase the likelihood of Schwannomatosis

Patients with the following characteristics do not fulfill diagnosis for Schwannomatosis:

Germline pathogenic NF2 mutation

Fulfill diagnostic criteria for NF2

First‐degree relative with NF2

Figure 4. Histopathological examination. (a) Compact spindle cells arranged in short bundles, composed of focal hypercellular (Antoni-A) areas and hypocellular areas (Antoni-B) with no malignant findings (H–E). (b) The tumor cells are positive for S-100 (Immunohistochemistry). Scale bar: 100 μm in (a) and (b).