Ancient Schwannoma in the Nasal Cavity—A Rare Case Report With Brief Literature Review

Graphical abstract

Keywords

ancient schwannoma / nasal cavity / S‐100 / schwannoma

1 Introduction

Schwannomas, also known as neurilemmomas, are benign tumors, arising from any nerve covered by a Schwann cell sheath, which includes the cranial nerves (except for optic and olfactory), the spinal nerves, and autonomic nervous system [1]. While schwannomas are relatively common tumors in the head and neck region, they are rare within the nasal cavity and paranasal sinuses, comprising only a small fraction of benign nasal masses [1, 2]. Among the various subtypes of schwannomas, ancient schwannoma is an uncommon variant characterized by degenerative changes, including cystic alterations, nuclear atypia, hemorrhage, and hyalinization, which typically occur in longstanding tumors. These changes can complicate the diagnosis, as they may mimic more aggressive neoplasms on both imaging and histological examination [1].

Ancient schwannoma was first described by Ackerman and Taylor in 1951 [3], and has since been recognized as a unique subtype of schwannoma that demonstrates “ancient” or degenerative features [4]. These alterations are thought to result from slow tumor growth, leading to areas of ischemia within the tumor, which then undergo degeneration over time. Due to these distinct histopathological features, distinguishing an ancient schwannoma from other benign or malignant nasal tumors requires careful analysis, particularly when the lesion presents with atypical radiological or histopathological features [4].

Imaging studies, particularly computed tomography (CT) and magnetic resonance imaging (MRI), play an essential role in evaluating the extent and behavior of nasal schwannomas [2]. On CT, nasal schwannomas may appear as well‐defined, expansile masses with pressure effects on adjacent bony structures, including the nasal septum, ethmoid sinuses, and maxillary walls. MRI can further characterize these lesions by demonstrating the heterogeneous nature of the mass due to cystic or hemorrhagic changes, typical of ancient schwannoma. T1‐weighted MRI images often show iso‐ or hypointense signals, while T2‐weighted images reveal hyperintense areas corresponding to cystic degeneration, making MRI valuable for preoperative assessment and surgical planning [2].

Given their rarity in the nasal cavity, ancient schwannomas can be misdiagnosed as other benign or malignant conditions, emphasizing the importance of a comprehensive diagnostic approach. This case report illustrates the presentation, diagnostic challenges, and successful management of a rare ancient schwannoma in the nasal cavity, underscoring the role of a multidisciplinary approach involving clinical evaluation, radiology, histopathology, and surgical excision in achieving optimal patient outcomes.

2 Case Report

A 42‐year‐old female presented to the ENT outpatient department (OPD) with complaints of worsening left nasal obstruction and epistaxis over the last 9 months. Other associated symptoms like anosmia, headaches and face pain were not present. There was no history of trauma. The patient had no relevant family history or comorbid conditions. Anterior rhinoscopy was ordered for the patient and showed that the left nasal cavity was nearly entirely filled with a massive smooth, dark‐red, bleeding polypoid mass. The polyp seemed to be covered by normal nasal mucosa and had a hard firmness. The mass bled on touch. The site of attachment could not be clearly determined.

Radiology: Contrast‐enhanced CT of paranasal sinuses was ordered which showed a large predominantly enhancing with small patchy area of intensely enhancing soft tissue mass in left nasal cavity, causing complete obliteration of left nasal cavity. This large soft tissue mass was causing extrinsic compression of surrounding bones which were nasal septum medially, left lateral wall laterally, hard palate inferiorly and superiorly it was causing extrinsic compression on the left ethmoid sinuses. These bony walls were expanded with cortical thinning. The mass measured approximately 5.8 cm (anteroposterior [AP]) × 3.8 cm (transverse [TR]) on axial imaging and 4.5 cm (superoinferior [SI]) on coronal image (Figure 1). The right nasal cavity was significantly compromised and the right sided nasal turbinates were atrophied. Complete opacification of left maxillary sinuses with obstruction of left ostiomeatal unit was also present.

MRI of the paranasal sinuses with contrast showed a well marginated oval shaped heterogeneously enhancing lesion measuring approximately 6.5 cm (AP) × 3.3 cm (TR) × 4.3 cm (craniocaudal [CC]) in the left nasal cavity causing its marked expansion and posteriorly bulging into the nasopharynx causing partial luminal compromise. It was causing significant narrowing of the left ostiomeatal unit and fronto ethmoidal recess with retained secretions in the left side paranasal sinuses. The nasal septum was deviated towards the right side with compressed right side turbinates. The lesion was causing thinning with bony remodeling of inferomedial wall of left orbit without intraocular extension. The lesion was isointense on T1 and heterogeneously hyperintense on T2 with mild restricted diffusion and areas of blooming on multiple‐echo recombined gradient echo (MERGE) images. Left side turbinates were not separately visualized (Figure 2).

Correlating endoscopic and radiological findings, the lesion was scheduled for removal under general anesthesia (GA). After proper pre‐anesthetic workup, the patient was found to be fit for surgery. An incision was made inferiorly along the floor of nasal cavity, starting in the left nasomaxillary groove. After elevating the flap, the skin incision was made between the mass and the ala. The mass was seen to be in close approximation to the lateral wall as well as the inferomedial wall of the orbit. The mass was completely excised without any major complications. The excised mass was sent to the department of pathology for histopathological examination, fixed in 10% formaldehyde.

On gross examination, the solid mass measured approximately 5 cm × 4 cm × 1 cm. The external surface was grey white with tiny areas of hemorrhage. On cut, the mass was grey white to grey yellow homogeneously and no areas of necrosis were identified grossly. Tissue sections were given for routine hematoxylin and eosin stain examination.

Microscopically, the lesion was circumscribed and encapsulated. It showed two distinct areas, consistent with schwannoma. The first area was the hypercellular (Antoni A) area, which was formed by nuclear palisading and interlacing bundles of spindle‐to‐oval cells. These cells had fibrillary eosinophilic cytoplasm, inconspicuous nucleoli, and spindle‐to‐oval nuclei with granular chromatin. The second area was the hypocellular (Antoni B) and composed of loose microcystic areas interspersed with hyalinized congested arteries and moderate lymphocytic infiltration. The hypocellular area also showed evidence of hemorrhage especially around the congested vessels. Focal areas showed hyalinization, thick‐walled dilated blood vessels, hemorrhage, nuclear atypia and hemosiderin deposition. Mitotic activity was inconspicuous. These additional characteristics pointed towards ancient schwannoma (Figure 3).

Immunohistochemistry (IHC) was performed for S‐100 (mouse monoclonal, clone 4C4.9, Biocare Medical), SMA (mouse monoclonal, clone IA4, Biocare Medical), CD34 (mouse monoclonal, clone QBEnd/10, Biocare Medical) and CD10 (mouse monoclonal, clone 56C6, Biocare Medical). IHC showed strong diffuse positivity for S‐100, while SMA, CD34, and CD10 were negative. The Ki‐67 (mouse monoclonal, clone MIB‐1, Biocare Medical) proliferation index was less than 5% (Figure 4). Immunohistochemical findings were consistent with histopathological observations. The final impression was given as ancient schwannoma, left nasal cavity.

At 2 months of follow‐up, patient was doing well with no evidence of recurrence.

3 Discussion

Schwannomas exhibit various histopathological subtypes, including microcystic, cellular, plexiform, epithelioid, ancient, and neuroblastoma‐like variants [1]. An extensive literature review revealed a limited number of documented cases of schwannomas originating from the nasal septum, dating back to 1943 [5]. The English language literature on nasal cavity schwannomas has been reviewed by two primary groups. The first was by Berlucchi et al. in 2000, who published a case report and literature review documenting a total of 12 cases, including their own [5]. Later, between 2000 and 2017, Min et al. reviewed an additional 19 cases [6]. Nasal septum schwannoma was first described by Bogdasarian and Stout in 1943 [7].

Ancient schwannoma is a rare histological variant of schwannoma with characteristic degenerative changes. Its occurrence in the nasal cavity is unusual, with only a few cases reported in the literature. A systematic search of PubMed, Scopus, and Web of Science identified a limited number of reported cases of ancient schwannoma involving the nasal region to date, including one case arising from the external surface of the nose (Table 1). Recent literature has reported additional cases of sinonasal ancient schwannoma, including several reports published in 2025, highlighting that although rare, the number of documented cases is gradually increasing [8–12]. These recent reports demonstrate similar clinical presentations, most commonly nasal obstruction and epistaxis, and reaffirm that complete surgical excision remains the treatment of choice with excellent prognosis.

The typical presentation includes discharge, nasal obstruction, epistaxis and anosmia, though such symptoms are often non‐specific and may overlap with more common nasal pathologies such as polyps or angiofibromas. The absence of symptoms like facial pain, or headache can further obscure the diagnosis. As for ancient schwannoma of nasal cavity the symptoms noted on literature review were obstruction, nasal discharge and anosmia/hyposmia [8–10]. Our case presented with history of left nasal obstruction and epistaxis.

The nasal cavity has thin network of veins, making it difficult to pinpoint the origin of nasal schwannomas. During surgery, it is challenging to locate the nerve attachment. Their potential source is thought to be the sympathetic, parasympathetic, or sensory nerves. The septal blood arteries are surrounded by sympathetic nerves that emerge from the stellate ganglion [12, 13]. The sphenopalatine ganglion's parasympathetic nerves innervate the septal mucous gland. The branches of the maxillary nerves (nasopalatine nerve) and ophthalmic nerves (anterior ethmoid nerve) give rise to the sensory nerves in the nasal septum. The olfactory bulb and nerve may be the source of olfactory groove schwannomas [6]. Anatomically, the middle meatus and, in rare instances, the nasal septum and lateral wall are the usual sources of nasal schwannoma [14, 15].

A high‐resolution CT scan can reveal information regarding the size and spread of tumors in cases with nasal cavity schwannomas. On a contrast‐enhanced CT scan, the tumors exhibit a weak and uneven enhancement pattern [2]. When it comes to identifying tumors from inflammatory alterations and assessing their extranasal expansions, MRI performs better than CT imaging. On T1‐weighted pictures, MRI signals exhibit an intermediate signal intensity. On T2‐weighted images, the signal intensity varies from intermediate to a heterogeneous high level [5]. Preoperative imaging might be useful in diagnosing and choosing the best surgical strategy and also the further plan of management [2]. MRI is more sensitive to the presence of contrast enhancement than CT. In a study by Kim et al., while most of the schwannomas (8 of 9, 88.9%) showed a mild and patchy enhancement pattern on contrast‐enhanced CT, all tumors showed marked enhancement on contrast‐enhanced MRI [2].

Histologically, ancient schwannoma is relatively underreported due to its rarity, with only a small number of publications detailing its characteristics. Although calcification may not be apparent on radiographs, Isobe et al. recommend considering ancient schwannoma when MRI reveals a hypervascular soft‐tissue mass with cystic regions and amorphous calcifications on radiographic images [16]. Despite these radiological clues, histopathological examination remains the definitive gold standard for diagnosis. On histopathology, schwannomas show two distinct cellular patterns: Antoni A, a hypercellular pattern with organized nuclear palisading, and Antoni B, a hypocellular, more loosely organized area. Ancient schwannomas, in particular, may exhibit additional degenerative changes, especially in Antoni B areas, such as nuclear atypia and pleomorphism, hyperchromasia, nuclear kinking, vascular hyalinization, diffuse fibrosis and hemosiderin deposition. Despite these atypical features, they remain benign and are characterized by low mitotic activity, making the prognosis excellent when appropriately managed [4]. Immunohistochemistry is also valuable in diagnosis, with S‐100 protein positivity serving as a hallmark of schwannomas due to its specificity for Schwann cells [4]. The differentiation between schwannoma and neurofibroma can be particularly challenging due to the overlap of their histological features. Neurilemmomas/schwannomas are typically solitary, tender, and exhibit degenerative changes. In contrast, neurofibromas are more often multiple, commonly associated with Von Recklinghausen's disease, and tend to be non‐tender with fewer regressive changes. Unlike neurilemmomas, neurofibromas are unencapsulated and consist of a mixed proliferation of all components of a peripheral nerve, including axons, Schwann cells, fibroblasts, and possibly perineural cells [17]. Schwannomas are highly selective for calretinin and CD56 on IHC, whereas neurofibromas a close differential diagnosis, are more sensitive for CD34 and factor XIIIa. Schwannoma was diagnosed in our instance due to strong immunostaining for S‐100 protein and negative results for CD34 [18]. However, hybrid tumors can occur, with areas of both neurofibroma and schwannoma within the same tumor, and these appear to be more common in schwannomatosis and NF1 and 2 [19–21]. Other differential diagnoses of sinonasal schwannoma include, fibromyxoma, juvenile nasopharyngeal angiofibroma, ectopic or secondary meningioma, glomangiopericytoma, leiomyomas, and solitary fibrous tumor [14].

Given the spindle cell morphology and unusual location, a range of differential diagnoses must be considered. The differential diagnosis of a spindle cell lesion in the nasal cavity includes nasal polyp, inverted papilloma, hemangioma, neurofibroma, and olfactory neuroblastoma. Histopathological examination along with immunohistochemistry is essential for accurate diagnosis [8, 9].

Complete surgical excision is therapy of choice for schwannomas of the nasal cavity. Although most schwannomas of the head and neck are encapsulated, certain sinonasal schwannomas are not, which makes en bloc tumor excision challenging [1, 22–24]. The size, location, and infiltration of surrounding structures of the tumor determine the surgical method. Limited nasal cavity schwannomas are often treated with transnasal excision, either with or without endoscopy. Open surgery is often saved for conditions that are more widespread. The majority of reports on endoscopic surgery date back to the last 20 years, and this method is quickly gaining popularity. After endoscopic surgery, no recurrence was noted, even in cases of significant illnesses [20].

4 Conclusion

Ancient schwannoma of the nasal cavity is a rare entity that can mimic other vascular and soft tissue lesions clinically and radiologically. A thorough understanding of its histopathological and immunohistochemical characteristics is essential for accurate diagnosis. Complete excision is usually curative, and histopathology plays a critical role in confirming the diagnosis and ruling out malignancy.

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