Malignant external otitis is typically an infection of the external auditory canal that can cause Pseudomonas osteomyelitis of the temporal bone. Methicillin-resistant Staphylococcus aureus (MRSA) can also cause malignant external otitis. Diagnosis is based on imaging and culture. Treatment involves administration of systemic, usually intravenous, antibiotic coverage for both organisms along with serial debridement of the ear canal and topical antibiotic/steroid therapy (eg, ciprofloxacin 0.3%/dexamethasone 0.1%).(MRSA) can also cause malignant external otitis. Diagnosis is based on imaging and culture. Treatment involves administration of systemic, usually intravenous, antibiotic coverage for both organisms along with serial debridement of the ear canal and topical antibiotic/steroid therapy (eg, ciprofloxacin 0.3%/dexamethasone 0.1%).
Malignant otitis externa (also called necrotizing otitis externa) is a rare, potentially life-threatening invasive infection of the external auditory canal that extends to the temporal bone and skull base. Mortality can be high, even with antibiotic therapy (1).
Soft tissue, cartilage, and bone are all affected by malignant external otitis. The osteomyelitis spreads along the base of the skull and may cause cranial neuropathies (VII usually affected first followed by IX, X, and XI) and may cross the midline.
Malignant external otitis occurs mainly in older patients, in immunocompromised patients, and/or those with diabetes (1). It is often initiated by Pseudomonas external otitis; methicillin-resistant Staphylococcus aureus (MRSA) can also cause this infection. In patients with severe immunosuppression (eg, advanced HIV), fungal etiologies should be considered, especially infections by Aspergillus and Candida species (1).
The term "malignant" refers to the presence of locally destructive progression and potentially life-threatening nature of the disease; there is no association with cancer or metastasis.
General reference
1. Long DA, Koyfman A, Long B. An emergency medicine-focused review of malignant otitis externa. Am J Emerg Med. 2020;38(8):1671-1678. doi:10.1016/j.ajem.2020.04.083
Signs and Symptoms of Malignant External Otitis
Malignant external otitis is characterized by persistent and severe, deep-seated otalgia (often worse at night), foul-smelling purulent otorrhea, and the presence of granulation tissue or in severe cases, exposed bone in the ear canal (usually at the junction of the bony and cartilaginous portions of the canal).
In severe cases, extension to involve adjacent cranial nerves (or their branches) may occur. Vestibular and cochlear nerve deficits may occur, as may varying degrees of conductive hearing loss. Facial nerve paralysis, and even lower cranial nerve (IX, X, or XI) paralysis, may ensue as this infection spreads along the skull base (skull base osteomyelitis) from the stylomastoid foramen to the jugular foramen and beyond.
Rarely, intracranial spread can cause meningitis or intracranial abscess (1).
Signs and symptoms reference
1. Long DA, Koyfman A, Long B. An emergency medicine-focused review of malignant otitis externa. Am J Emerg Med. 2020;38(8):1671-1678. doi:10.1016/j.ajem.2020.04.083
Diagnosis of Malignant External Otitis
Imaging (CT scan of the temporal bone, MRI of skull)
Culture
Biopsy
The diagnosis of malignant external otitis is suggested by high-resolution CT of the temporal bone, which may show increased radiodensity in the mastoid air-cell system, middle ear radiolucency (demineralization) in some areas, and bony erosion usually identified in the bony ear canal. MRI can also be used to evaluate skull base osteomyelitis, offering superior sensitivity to CT in detecting soft-tissue involvement, marrow changes, and intracranial complications of osteomyelitis (1).
Cultures are taken, and the ear canal must be biopsied. Examination of biopsied granulation tissue can help differentiate this disorder from a malignant tumor or neoplastic process (eg, squamous cell carcinoma) (2).
Acute phase reactants (eg, CRP, ESR) may be elevated.
Disease may sometimes be categorized into different severity levels based on the extent of involvement (3, 4).
Diagnosis references
1. Stocker M, Hempel JM. Patient cases with malignant otitis externa at the university clinic of Ludwig Maximilians University Munich from 2009 until 2020. Sci Rep. 2025;15(1):26367. Published 2025 Jul 21. doi:10.1038/s41598-025-11742-z
2. Handzel O, Halperin D. Necrotizing (malignant) external otitis. Am Fam Physician. 2003;68(2):309-312.
3. Thakur A, Tandon DA, Bahadur S, et al. Malignant externa otitis. Indian J. Otolaryngol. Head Neck Surg. 1996:48:114-120.
4. Long DA, Koyfman A, Long B. An emergency medicine-focused review of malignant otitis externa. Am J Emerg Med. 2020;38(8):1671-1678. doi:10.1016/j.ajem.2020.04.083
Treatment of Malignant External Otitis
Systemic antibiotics, typically a fluoroquinolone and/or an aminoglycoside/semisynthetic penicillin combination
Topical antibiotic/glucocorticoid preparations (eg, ciprofloxacin/dexamethasone)Topical antibiotic/glucocorticoid preparations (eg, ciprofloxacin/dexamethasone)
Rarely surgical debridement
Treatment of malignant external otitis is with systemic antimicrobial therapy, which is often empirically initiated. When feasible, multidisciplinary management with an otorhinolaryngologist and an infectious disease specialist is recommended to help determine the optimal setting of therapy (outpatient versus inpatient), antibiotic regimen, and duration of therapy. Antibiotic regimens should cover both Pseudomonas aeruginosa and Staphylococcus aureus. In addition to systemic antibiotics, treatment should also include topical ciprofloxacin/dexamethasone preparations (eg, ear drops, impregnated canal dressings) and serial debridement. . In addition to systemic antibiotics, treatment should also include topical ciprofloxacin/dexamethasone preparations (eg, ear drops, impregnated canal dressings) and serial debridement.
Treatment approaches differ depending on the severity of disease. Mild cases presenting without cranial nerve involvement and with optimized glycemic control may be managed in the outpatient setting, utilizing oral antibiotics, serial debridement, and close surveillance. Moderate to severe disease typically necessitates hospitalization and intravenous therapy.
Antibiotic treatment is typically a 6-week systemic (oral or IV) course of a culture-directed fluoroquinolone (eg, ciprofloxacin) and/or a semisynthetic penicillin (piperacillin–tazobactam or piperacillin)/aminoglycoside combination (for ciprofloxacin resistant Antibiotic treatment is typically a 6-week systemic (oral or IV) course of a culture-directed fluoroquinolone (eg, ciprofloxacin) and/or a semisynthetic penicillin (piperacillin–tazobactam or piperacillin)/aminoglycoside combination (for ciprofloxacin resistantPseudomonas). Mild cases may be treated with a high-dose oral fluoroquinolone (eg, oral ciprofloxacin 750 mg twice/day) on an outpatient basis with close follow-up. Topical preparations may be additionally used.). Mild cases may be treated with a high-dose oral fluoroquinolone (eg, oral ciprofloxacin 750 mg twice/day) on an outpatient basis with close follow-up. Topical preparations may be additionally used.
Extensive bone disease may require more prolonged antibiotic therapy.
Hyperbaric oxygen may be a useful adjunctive treatment, but its definitive role remains to be elucidated.
If the patient has diabetes, meticulous control of diabetes is essential, and consultation with an endocrinologist for strict diabetic control is recommended. In immunocompromised patients, immunotherapy may be stopped.
Frequent debridement, performed in office, is necessary to remove granulation tissue and purulent discharge. Usually surgery is not necessary, but surgical debridement to clear necrotic tissue or bony sequestra may be used for more extensive infections (1).
Treatment reference
1. Treviño González JL, Reyes Suárez LL, Hernández de León JE. Malignant otitis externa: An updated review. Am J Otolaryngol. 2021;42(2):102894. doi:10.1016/j.amjoto.2020.102894
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