Abstract
The authors present a case of Endolymphatic Sac Inflammatory Pseudotumour treated at our institution and reviewed the relevant literature. This is a benign lesion which arises due to chronic inflammation. It has similar clinical and radiological features as endolymphatic sac tumors and is diagnosed through histopathological examination. To date, there have been over 200 case reports of ELSTs but only 2 case reports of endolymphatic sac pseudotumour. This report highlights the clinical presentation, radiological features, histological characteristics, treatment, and clinical outcomes of endolymphatic sac inflammatory pseudotumours and explores their likely etiology and discusses possible treatment options. Endolymphatic sac inflammatory pseudotumour may represent the end of a spectrum of immune-mediated inflammatory disease of the endolymphatic sac. Based on the experience of managing inflammatory pseudo-tumours elsewhere in the body, there may be a role for high dose steroids in its management.
1
Introduction
Endolymphatic sac inflammatory pseudotumours (ELS-IPs) are benign, localized inflammatory lesions of unknown etiology. They have similar clinical presentation and radiological features as endolymphatic sac tumors (ELSTs) and can be differentiated only on histopathological examination . ELSTs have been well described in scientific literature with over 200 case reports. In contrast, ELS-IPs are a relatively new clinical entity, with only 2 cases described by Diaz et al in 2007 .
The two reported cases of ELS-IPs presented with non-specific audiovestibular symptoms. The first patient presented with a 3-month history of complete unilateral hearing loss, tinnitus, fullness, vertigo, and imbalance. The second patient presented with a 2-year history of unilateral aural fullness with intact hearing. Both cases were investigated with Computed Tomography of the temporal bone (CT-temporal bone) and Magnetic Resonance Imaging (MRI), which revealed irregular, gadolinium contrast-enhancing lesions in the region of the ELS associated with bony erosion. Intraoperative findings were of fibrous infiltration of the ELS with involvement of surrounding structures (otic capsule in the first patient, dural and lateral sinus in the second). No adjuvant treatments were administered. Under light microscopy, the ELS-IPs appeared as a chronic inflammatory infiltrate and fibrosis within normal endolymphatic sac epithelium. Both patients are well with no disease recurrence at 23 and 26 months respectively .
Inflammatory pseudotumours (IPs) occur throughout the body, with the majority developing in the orbit, lung and liver. Approximately 5% of IPs occur in the head and neck region, with 21 reported cases occurring in the temporal bone . They are often locally aggressive and present with symptoms related to mass effect or invasion of adjacent tissues. The treatment response of IPs varies with the site of the body—orbital pseudotumours are responsive to steroids/radiotherapy whereas lung and liver generally require surgery . Given the scarce clinical information about Endolymphatic Sac Inflammatory Pseudotumours (ELS-IPs), additional clinical information is required to further our understanding of the pathogenesis, diagnosis and optimal treatment of these rare lesions. Our objective is to contribute to the existing literature on ELS-IPs by presenting a case of ELS-IP treated at our institution and discuss the diagnostic approach and possible treatment modalities for ELS-IPs.
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Case report
The patient was a 54 year old Chinese female with a medical history of hypertension and hyperlipidemia who initially presented with short episodes of vertigo (1–3 min) related to posture 10 years prior to diagnosis with ELS-PT. Initially diagnosed as Benign Paroxysmal Positional Vertigo (BPPV), her vertigo was not debilitating and was treated with Epley’s manoeuvre. She responded to the manouvre and was symptom free for 5 years. Subsequently, her symptoms recurred and became more severe—her vertigo was present daily, lasted for a few hours each time, was associated with tinnitus, headaches, moderate unilateral hearing loss and nausea, and was aggravated by physical exertion. She was diagnosed to have Meniere’s Disease and treated accordingly with vestibular sedatives.
Examination was unremarkable with an intact tympanic membrane, type A tympanogram as well as negative Dix Hallpike and head thrust tests. She did not have any neurological deficits such as facial nerve palsy or cerebellar dysfunction. Audiology showed asymmetric SNHL of the left ear (~ 60 dB) with retained hearing of the right ear (~ 30 dB).
A CT scan of the temporal bone showed a 1.2×1.2×0.7 cm irregular osteolytic lesion with internal bony spicules in the retrolabyrinthine region of the left petrous temporal bone ( Fig. 1 A ), with T1W MRI showing a high signal lesion ( Fig. 1 B) .
The patient was treated with excision of the left endolymphatic sac lesion via a transmastoid approach along with mastoid obliteration with abdominal fat. Histological examination revealed chronic inflammation, fibrosis, foreign body giant cell reaction and cholesterol clefts within the columnar epithelium of a normal endolymphatic sac, consistent with that of an ELS-IP ( Fig. 2 ) .
The patient is currently symptom free and is followed up at regular intervals with radiologic surveillance. She has completed 1 year of follow up, with no clinical or radiologic evidence of tumour recurrence ( Fig. 3 ). Her hearing in the left ear has deteriorated from moderate deafness (60 dB) to profound deafness, a consequence of the hearing ablative surgery.
2
Case report
The patient was a 54 year old Chinese female with a medical history of hypertension and hyperlipidemia who initially presented with short episodes of vertigo (1–3 min) related to posture 10 years prior to diagnosis with ELS-PT. Initially diagnosed as Benign Paroxysmal Positional Vertigo (BPPV), her vertigo was not debilitating and was treated with Epley’s manoeuvre. She responded to the manouvre and was symptom free for 5 years. Subsequently, her symptoms recurred and became more severe—her vertigo was present daily, lasted for a few hours each time, was associated with tinnitus, headaches, moderate unilateral hearing loss and nausea, and was aggravated by physical exertion. She was diagnosed to have Meniere’s Disease and treated accordingly with vestibular sedatives.
Examination was unremarkable with an intact tympanic membrane, type A tympanogram as well as negative Dix Hallpike and head thrust tests. She did not have any neurological deficits such as facial nerve palsy or cerebellar dysfunction. Audiology showed asymmetric SNHL of the left ear (~ 60 dB) with retained hearing of the right ear (~ 30 dB).
A CT scan of the temporal bone showed a 1.2×1.2×0.7 cm irregular osteolytic lesion with internal bony spicules in the retrolabyrinthine region of the left petrous temporal bone ( Fig. 1 A ), with T1W MRI showing a high signal lesion ( Fig. 1 B) .
