Erosive External Otitis: A Novel Distinct Clinical Entity of the External Auditory Canal in Nonimmunosuppressed Individuals

Abstract

Objective

We introduce erosive external otitis (EEO) as a novel erosive process of the external auditory canal in the absence of diabetes or immune suppression.

Study Design

Case series and literature review.

Setting

Tertiary referral center.

Patients

Primary eligibility criteria included patients who had an erosive process of their external auditory canal in the absence of diabetes or immune suppression.

Intervention

Surgical debridement and split-thickness skin grafting.

Main Outcome Measures

Uneventful wound healing and disease-free long-term follow-up after surgical debridement and skin grafting.

Results

Three cases of EEO in the absence of immune suppression or diabetes were diagnosed and treated. All patients required surgical debridement and skin grafting as part of their management. All recovered uneventfully from surgery and had no evidence of recurrence on long-term follow-up.

Conclusion

We propose that EEO, which occurs in the absence of immune suppression or diabetes, is a clinical entity that is distinct from the more commonly diagnosed malignant external otitis and that the management of EEO is primarily surgical debridement with skin grafting.

Malignant external otitis (MEO) was first described in 1959 as an invasive infection of the external auditory canal (EAC) and cranium base (1). This well-known disease typically arises in elderly patients with diabetes mellitus or in immunosuppressed individuals (2). In this case series, we describe erosive external otitis (EEO), an erosive process of the EAC that occurs in healthy patients with a clinical presentation and treatment that are distinct from MEO.

Case Report 1

Patient 1 is a 21-year-old woman with history of Down syndrome and chronic intermittent Eustachian tube dysfunction. She was regularly seen by an otolaryngologist for conductive hearing loss thought to be secondary to Eustachian tube dysfunction and routine cerumen removal. The patient swims daily and had no complaints of any otalgia or otorrhea. On previous routine otologic examinations, the patient was noted to have mild bilateral tympanic membrane (TM) retraction without evidence of cholesteatoma.

Eight months before presentation, the patient was seen for routine otologic examination. Examination of the left EAC revealed significant cerumen impaction with some purulent material on the floor of the canal beneath the cerumen. The patient had no complaints of otalgia or otorrhea. After microscopic debridement, the patient was instructed to use cortisporin otic drops for 1 week in addition to Domboro’s solution in both ears after swimming.

Eight months after the initial finding of purulent material in the left EAC, microscopic examination revealed exposed bone of the floor of the EAC. The patient denied any instrumentation to the external canal and had no symptoms of otalgia or otorrhea. The patient was started on ciprofloxacin hydrocortisone otic drops and instructed to follow up in 8 weeks.

At the next visit, the patient still did not have any evidence of otalgia or otorrhea. Examination of the floor of the left EAC revealed persistent bony erosion with some bony sequestrum that was cleaned under microscopy. Temporal bone computed tomography showed shallow bony erosion on the floor of the left EAC. A fasting glucose was obtained, which was within normal limits.

Despite continued ciprofloxacin otic drops for 7 months, the bony erosion on the left EAC did not improve. Subsequently, the patient was brought to the operating room for canalplasty with split-thickness skin graft. Intraoperatively, the exposed bone was drilled down until fresh smooth bone was encountered. A split-thickness skin graft obtained from the postauricular region was used to graft the exposed bony canal. Specimens removed from the operative site were sent to the laboratory for gram stain, culture, and histopathologic examination. There was no evidence of mycobacterium, fungal, or bacterial organisms seen within the specimen. Cultures were negative after 2 weeks. Final pathologic diagnosis of the soft tissue was mild, nonspecific inflammation (Fig. 1). Pathologic examination of the bony fragments did not show evidence of polymorphonuclear leukocyte infiltration and necrosis typically seen in osteomyelitis (Fig. 2).

FIG. 1.

Histopathology of soft tissue obtained from surgical debridement of the left EAC of Patient 1 showing moderate infiltration by polymorphonuclear cells (black arrows) consistent with mild, nonspecific inflammation (hematoxylin-eosin stain).

FIG. 2.

Histopathology of bone fragments obtained from surgical debridement of the left EAC of Patient 1 showing moderate polymorphonuclear infiltration (black arrows) and no evidence of bone necrosis (hematoxylin-eosin stain).

The patient did well postoperatively with complete healing of the canal 2 weeks postoperatively. The patient continues to swim regularly, and the canal remains intact 2 years after surgery.

Case Report 2

Patient 2 is an 83-year-old man with no significant medical history who had been followed for gradual down-sloping sensorineural hearing loss. The patient had been wearing hearing aids bilaterally for 4 years before current presentation. He had no previous otologic surgeries and denied instrumentation of the EAC.

The patient presented for his annual otologic examination complaining of intermittent otorrhea from the right ear with minimal tenderness. Examination of the right EAC revealed an intact TM with a soft tissue shelf (granulation tissue) immediately lateral to the TM. There was an eroded area of exposed bone lateral to this shelf on the floor of the EAC. Microdebridement and biopsy of the thickened soft tissue and bony sequestrated fragments within the EAC revealed chronically inflamed granulation tissue. Gram stain and culture revealed no organisms. Final cultures were negative. A temporal bone computed tomographic scan suggested osteomyelitis. Erythrocyte sedimentation rate (ESR) was normal. A hemoglobin A1c was obtained, which was within normal limits. The patient was started on oral and topical ciprofloxacin.

Despite continued oral and topical ciprofloxacin for 4 months, the bony erosion of the right EAC did not improve. The patient was taken to the operating room for canalplasty with split-thickness skin graft. Intraoperatively, the exposed bone and granulation tissue were removed, and split-thickness skin graft obtained from the patient’s right upper inner arm was used to cover the bony defect.

Specimens removed from the operative site for histology and culture showed no evidence of malignancy, mycobacterial, fungal, or bacterial growth. Final pathologic diagnosis of the soft tissue was chronic inflammation. Pathologic examination of the bony fragments showed nonspecific inflammation and no evidence of osteomyelitis or cholesteatoma.

The patient did well postoperatively, and the canal was well-healed 4 months after surgery.

Case Report 3

Patient 3 is a 60-year-old woman with no significant medical history who presented to the clinic complaining of several months of mild right ear pain and foul-smelling otorrhea. The patient reported that she has had intermittent itchiness of her right ear for several years. She denied previous otologic surgeries or instrumentation of the EAC and did not use hearing aids. Microscopic examination of the right EAC revealed an intact TM with granulation tissue extending laterally from the annulus and separated from the annulus by an area of exposed bone. Bony sequestrations were removed, and the patient was started on ciprofloxacin otic drops. A temporal bone computed tomography was obtained, which revealed shallow bony erosion of the right EAC. The patient was started on oral ciprofloxacin in addition to the topical regimen. Hemoglobin A1c was obtained, which was normal. ESR also was normal.

Despite 2 months of systemic and topical ciprofloxacin treatment, the bony erosion of the right EAC did not improve. The patient was taken to the operating room for canalplasty with split-thickness skin graft. Intraoperatively, the exposed bone and granulation tissue were removed, and a split-thickness skin graft obtained from the postauricular area was used to cover the bony defect. Subsequently, the area healed without difficulties.

Specimens removed from the operative site were sent to the laboratory for gram stain, culture, and histologic examination. There was no evidence of mycobacterial, fungal, or bacterial organisms seen within the specimen. Cultures were negative after 2 weeks. Final pathologic diagnosis of the soft tissue was chronic inflammation. Pathologic examination of the bony fragments showed no evidence of osteomyelitis.

DISCUSSION

We propose that EEO is an erosive process of the EAC that is distinct from MEO. The diagnosis of MEO is made by a combination of clinical presentation (usually of severe otalgia with otorrhea in a patient who is elderly diabetic or immunocompromised), elevated ESR, aural culture of Pseudomonas aeruginosa, and temporal bone computed tomographic scans indicative of bony erosion (3,4). The treatment of MEO is prolonged systemic anti-pseudomonal antibiotics, usually a fluoroquinolone for 6 to 8 weeks. Surgical treatment is reserved only for rare instances in which patients do not improve after correction of the underlying medical problem and systemic antibiotics (2).

Here, we describe an erosive process of the EAC in 3 patients with no history of diabetes or known systemic immune suppression. Although one of our patients described in this case series is elderly (age 83), he is in otherwise excellent health. The clinical presentation of EEO is mild, with little or no aural discomfort. Aural cultures do not show P. aeruginosa isolates, and patients have ESR within reference range. Specimens obtained from patients with EEO during surgical debridement showed a more benign, nonspecific pattern of inflammation, as opposed to the intense polymorphonuclear infiltration and necrosis observed in MEO (5). Finally, we have found that the most expedited therapy for EEO is surgical debridement with a split-thickness skin graft. The skin graft donor sites for our patients were chosen depending on the amount of graft needed.

The pathophysiology for EEO is not clear. One possibility is that chronic moisture within the EAC may lead to chronic inflammation and increased susceptibility to infection. One of our patients described in this series (Case 2) did use a hearing aid before the presentation of EEO, which could contribute to elevated moisture in the EAC. The first patient presented (Case 1) swam daily, and this consistent water exposure may have been a factor in the development of EEO. Still, it is likely that the pathophysiology for the development of EEO is multifactorial.

CONCLUSION

In this case series, we describe a distinct erosive process of the EAC affecting healthy patients in the absence of immunocompromise, diabetes mellitus, or Pseudomonas infection. The cause of EEO is unclear because the patients in our series differed widely in sex, age, water exposure, or hearing aid use. After the diagnosis of EEO, attempts at treating the erosive process medically with topical and systemic antibiotics did not result in clinical improvement. It is our recommendation that surgical management is the most expedient means to resolve this condition.