A case of Langerhans cell histiocytosis localized in the temporal bone,which presented as sudden sensorineural hearing loss: A case report and review of the literature

Abstract

Sudden sensorineural hearing loss is a condition marked by a rapid decline in hearing, defined as a decrease of 30 dB or more across three adjacent audiometric frequencies within 72 h. It can result from various factors, including ischemic events, infections, or tumors like meningioma and schwannoma, and in rare cases, may be linked to Langerhans histiocytosis, which involves an accumulation of specific immune cells. This document reviews literature and presents a case study of a 24-year-old male from Iran diagnosed with sudden sensorineural hearing loss due to Langerhans cell histiocytosis. The patient, who had diabetes insipidus, showed eosinophil-rich lesions with CD1a-positive, S100-positive, and Cyclin D1-positive cells. After 6 months of chemotherapy, there was no change in hearing levels. This case report underscores the importance of considering an occupying lesion in cases of sensorineural hearing loss, particularly when there are indications of additional paraneoplastic conditions.

Introduction

Sudden sensorineural hearing loss (SSNHL) is known by a rapid onset of hearing loss greater than 30 dB across at least three adjacent audiometric frequencies, occurring within 72 h. ¹

SSNHL can appear as either unilateral (affecting one ear) or bilateral (affecting both ears); when bilateral, the high-frequency loss is typically symmetrical. ²

The estimated prevalence of SSNHL is between 5 and 20 cases per 100,000 individuals annually. ³

While recovery from SSNHL is not guaranteed and largely depends on the underlying cause, there are instances of partial recovery, and, though rare, some individuals experience total recovery. Factors that influence hearing recovery after SSNHL include the degree of hearing loss, the specific frequencies affected, the presence of vertigo, and the time elapsed between the onset of hearing loss and the initiation of treatment. ²

The etiology of most cases of SSNHL is idiopathic, meaning the cause is unknown. However, various suspected causes have been proposed, with vascular compromise being the most widely accepted theory. The cochlea, which is responsible for hearing, is supplied by two small terminal arteries, making it particularly vulnerable to damage due to its small diameter and lack of collateral circulation. ²

Unilateral SSNHL often presents similarly to ischemic vascular disorders, such as amaurosis fugax (temporary vision loss) and transient ischemic attacks. There are several theories regarding the pathogenesis of idiopathic SSNHL, including potential autoimmune causes such as systemic lupus erythematosus, ⁴ Behçet’s disease, ⁵ multiple sclerosis, ⁶ and Cogan’s syndrome. ²

Infections related to SSNHL include meningitis, fungal meningitis, AIDS, ⁷ mumps, ⁸ syphilis, ⁹ Lassa fever, ¹⁰ mycoplasma, ¹¹ Lyme disease, ¹² and Toxoplasma gondii infection. ¹³ Certain endocrine disorders, such as diabetes mellitus ¹⁴ and hypothyroidism, ¹⁵ some hematologic situations like sickle cell anemia, ¹⁶ as well as cancers like vestibular schwannoma, petrous meningiomas, ¹⁷ Ewing sarcoma, ¹⁸ metastatic adenocarcinoma, ¹⁹ Langerhans histiocytosis (LHC), ²⁰ leptomeningeal carcinoma, and medulloblastoma. ²¹

The histiocytoses are rare conditions characterized by the accumulation of cells thought to be derived from dendritic cells or macrophages. Their clinical manifestation ranges from mild to severe and, sometimes, life-threatening forms. ²² Langerhans cell histiocytosis (LCH) is diagnosed based on clinical, radiological, and histopathological findings that show lesions containing inflammatory cells, along with CD1a⁺ and CD207⁺ histiocytes, which are common markers of epidermal Langerhans cells. ²³

Annual LCH incidence has been reported to be 4.6 cases/million children <15 years old and estimated at one to two cases per million adults. ²⁴ The clinical presentation at onset can vary widely, ranging from a self-limiting disease affecting a single organ to multisystemic manifestations that may require chemotherapy or targeted therapy. ²⁵ While LCH can affect any organ, it most commonly involves the bones (80%), followed by the skin (33%), pituitary gland (25%), liver (15%), spleen (15%), bone marrow (15%), lungs (15%), lymph nodes (5%–10%), and central nervous system (CNS) (2%–4%). The liver, spleen, and hematopoietic system are considered high-risk organs, whereas the skin, bones, lungs, lymph nodes, pituitary gland, and CNS are classified as low-risk organs. ¹³

Bone manifestations can arise in any bone; however, the fingers and feet are regularly unaffected. The presence of both uni- or multifocal osteal involvement does now no longer implies a chance of different systemic manifestations. In pediatric cases, the maximum not common manifestation is a lytic lesion within the skull, which could regularly be asymptomatic. Other often affected regions generally consist of axial and proximal bones, which include the femur, humerus, ribs, vertebrae, and pelvis. Certain locations, just like the temporal, orbit, sphenoid, ethmoid, and zygomatic bones, are connected to an accelerated chance of crucial anxious device involvement. ¹³

Diabetes insipidus is the most common manifestation and can arise along with panhypopituitarism. Other neurological signs and symptoms may be categorized into number one types: tumors and neurodegenerative lesions. The scientific manifestations of tumoral infiltration or masses are primarily based on their location, and all signs and symptoms are possible, inclusive of deficits, seizures, palsies, and adjustments in behavior. The symptoms related to degenerative lesions are progressive, including extrapyramidal syndrome, cerebellar syndrome, pseudobulbar palsy, or cognitive decline. ¹²

The work has been reported in line with the SCARE criteria. ²⁶

Case report

A 24-year-old male patient from Iran was referred to our tertiary care facility with a primary complaint of SSNHL, which had developed 5 months prior to his consultation. The condition did not improve despite a full course of oral prednisolone. In addition, the patient had been receiving treatment with desmopressin for 7 years due to a diagnosis of neurogenic diabetes insipidus, which is characterized by polyuria. Medical reports indicated that during the evaluation for the etiology of his diabetes insipidus, a brain magnetic resonance imaging (MRI) revealed a lesion in his left sphenoid and sella. The patient was advised to undergo surgery at that time, but refused.

To assess the unilateral hearing loss that failed to respond to corticosteroid therapy, imaging studies (temporal MRI) were conducted to exclude the possibility of an occupying lesion that might compress or affect the cochlear nerve. The imaging revealed a lesion occupying the left mastoid region, which had extended into the left cerebellopontine angle. Consequently, the patient was referred for a comprehensive evaluation (Figure 1).

Figure 1.

(a) T1 axial view shows an intermediate to high signal lesion. (b) T2 axial view shows hyper-intense lesion. (c) Temporal CT scan demonstrates a destructive lesion in the left attic.

Upon arrival, a thorough physical examination of the head and neck was conducted. Both tympanic membranes were assessed and found to be intact, with no preauricular edema observed. Furthermore, there was no evidence of lymphadenopathy. During the audiological evaluation, the Weber test indicated lateralization to the right ear, while the Rinne test produced a positive result in both left and right ears. The assessment of the facial nerve demonstrated normal functionality.

No signs of hepatosplenomegaly or dermatological rashes were noted during the examination. Audiometric evaluation revealed severe hearing loss across all frequencies, ranging from 60 to 70 dB, specifically in the left ear. Consequently, the patient was scheduled for a biopsy to determine the pathological nature of the identified mass. The biopsy procedure was performed under general anesthesia, during which a posterior auricular incision was made, followed by a mastoidectomy and elevation of the tympanomeatal flap. A significant mass was observed in the left attic and aditus, and an incisional biopsy was executed via a trans-mastoid approach. The results of the frozen section analysis confirmed a diagnosis of LHC.

In the pathologic report, the photomicrographs reveal a destructive lesion characterized by a rich eosinophilic infiltration. The primary differential diagnoses for this lesion encompass a range of conditions, including inflammatory, reactive immune-mediated processes, drug reactions, parasitic infestations, and neoplastic disorders. ²⁷ The lesion contains sheets of large, round to oval cells that test positive for CD1a, S100, and Cyclin D1. These cells exhibit folded nuclei and coffee bean-shaped nuclear grooves, accompanied by abundant pale to eosinophilic cytoplasm. Notably, there is minimal nuclear atypia, and atypical mitotic figures are absent. CD1a is a specific marker for LCH. Unfortunately, Langerin immunohistochemistry was not available to confirm the presence of Birbeck granules. Cyclin D1 serves as a crucial marker to differentiate between reactive and neoplastic forms of histiocytosis (Figure 2). ²⁸

Figure 2.

(a) Hematoxylin and eosin stain (H&E): the photomicrographs show an eosinophil-rich destructive lesion (power magnification 400×). (b) Immunohistochemistry (IHC) (positive for S100). (c) IHC (positive for Cyclin D1). (d) IHC (positive for Cd1).

Ultimately, the patient was referred for systemic evaluation and possible scheduling for chemotherapy to an expert oncologist. Following the evaluation in 6 months, it was observed that the hearing level neither exhibited signs of deterioration nor improvement.

Discussion

Nenad Arsovic et al. reported in 2013 on a 47-year-old male patient experiencing progressive unilateral sensorineural hearing loss in the left ear, accompanied by retroauricular soft tissue swelling. A computed tomography scan of the temporal bone revealed a lytic, destructive lesion in the mastoid pneumatic space, extending toward the middle and posterior cranial fossa without intracranial involvement. An MRI showed an expansive tumor mass eroding the mastoid process and infiltrating the dura. Notable findings included narrowing of the left sigmoid sinus and decreased blood flow velocity. Post-contrast imaging indicated a significant increase in the T1-weighted signal within the tumor.

During surgery via a retroauricular incision, a mastoid cavity tissue sample was collected for histopathological analysis, which revealed CD1- and S100-positive Langerhans cells and a mixed infiltrate of eosinophils, macrophages, and lymphocytes, leading to a diagnosis of eosinophilic granuloma.

Following surgery, skeletal scintigraphy demonstrated intense radionuclide accumulation in the left mastoid process. The patient underwent postoperative radiotherapy with a total dose of 20 Gy. A subsequent computed tomography showed complete regression of the lesion, although the hearing loss persisted unchanged. ²⁰

In 2010, Suzuki et al. published a case report detailing a 56-year-old woman diagnosed with LCH of the petrous bone, who presented with a sudden onset of sensorineural hearing loss and vertigo, absent any other neurological deficits. This clinical presentation closely resembled that of idiopathic SSNHL, rendering the differential diagnosis particularly challenging. It was not until neuroimaging revealed a lesion in the petrous bone that a definitive diagnosis could be established. The patient subsequently underwent surgical excision of the lesion via the transpetrosal approach and received postoperative chemotherapy comprising vinblastine, methotrexate, 6-mercaptopurine, and prednisolone. Despite the absence of hearing recovery, the patient achieved complete remission and is currently disease-free. This case highlights the necessity for healthcare providers to consider that sudden hearing loss may indicate an underlying condition necessitating further neuroimaging and histological evaluation to ensure accurate diagnosis and appropriate treatment. ²⁹

About treatment, regrettably, even with our advanced understanding of LCH pathogenesis, primary treatment still relies on data with low evidence levels. ²³

We summarized the characteristics of the patients presented in these two case reports in Table 1.

Table 1.

The summarized characteristics of the patients in the two previous case reports.

Author	Year	Country	Age	Sex	Ear side	Post-op radiotherapy/chemotherapy	recurrence	Primary hearing level	Post-treatment hearing level
Arsovic et al. 20	2013	Serbia	47	Male	Left	Radiotherapy	No	—	No change
Suzuki et al. 29	2010	Japan	56	Female	Left	Chemotherapy	No	50 db	No change

Despite advances in unraveling the pathogenetic mechanisms of LCH, the modern preferred first-line management of multifocal LCH remains empirically derived chemotherapy. ¹³ Overall consequences have progressed in LCH scientific trials over the last decades, though progression-free survival among high-threat sufferers remains at much less than 50%. Skin-limited LCH can be managed with topical steroids or, potentially, oral methotrexate or thalidomide. For single-bone lesions located near low-risk CNS sites, curettage or nonsteroidal anti-inflammatory medications can be recommended, while chemotherapy should be administered when there is CNS involvement. Treating CNS symptoms is challenging, particularly for neurodegenerative lesions. ¹²

This case report aims to present a patient diagnosed with LHC, initially misidentified as a primary case of diabetes insipidus, which subsequently manifested as a refractory case of SSNHL. A comprehensive evaluation revealed an occupying lesion in the left attic, which was surgically excised and subsequently diagnosed as LHC. The patient has been referred for chemotherapy following the surgical intervention.

Conclusion

The primary emphasis of this case report is that all neuro-otologists should consider systemic etiologies and tumors as potential causes of SSNHL, especially in cases that do not respond to medical therapy.