Introduction

Otomycosis is an infection in the external ear canal and the inner ear. It can occur de novo in a patient with predisposing factors or appear as a complication of the use of broad-spectrum antibiotics. This is caused by different types of fungi, mainly Candida and Aspergillus, highlighting the species Aspergillus niger (the most common in this condition), Aspergillus alliaceus, Aspergillus candidus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus terreus, and Aspergillus versicolor¹. A rare and potentially fatal complication is otomastoiditis².

This disease can present clinically with otorrhea, otalgia, pruritus, and tinnitus and is more common in patients with predisposing factors such as immunocompromise, living in tropical or subtropical climates, insulin resistance and a history of storing brick and cement fragments in the home; important data to support the suspicion of the final diagnosis³.

Case report

A 61-year-old woman, resident of Mexico City, presented with left otalgia of 7 days of evolution, of insidious onset, associated with fetid seropurulent otorrhea and progressive hearing loss. Her personal history included prediabetes, systemic arterial hypertension, previous hospitalization for hypokalemic paralysis, storage of brick, and cement fragments in her home. On physical examination, bone fragments were observed in the left external auditory canal, foul-smelling purulent discharge, and loss of integrity of the tympanic membrane. Plain and contrast-enhanced computed tomography of the skull showed left mastoid destruction, with no evidence of neuroinfection (Fig. 1).

Figure 1 Cranial CT in contrast-enhanced phase, axial section: loss of pneumatization of the left mastoid cells associated with bone destruction is observed. 

A left mastoidectomy with tissue debridement was performed. The histopathological study reported fungal structures compatible with Aspergillus spp. (Fig. 2), later identified as Aspergillus terreus by genetic sequencing. Treatment with oral voriconazole was started for 6 weeks, with adequate clinical and imaging response, without subsequent neurological alterations, and with complete resolution of the condition.

Figure 2 Periodic acid-Schiff stain in mastoid bone biopsy sample: hyaline, septate, thin-walled hyphae are observed, with dichotomous branches at 45 degrees. 

Discussion

A case was presented with the diagnosis of Aspergillus otomastoiditis confirmed by histopathological report and genetic sequencing. This was treated satisfactorily with a medical and surgical approach, with favorable evolution. The diagnosis requires a high level of suspicion according to risk factors and epidemiological context since the prognosis worsens exponentially when these are delayed and the initial clinical course can be insidious. In the case presented here, timely detection prevented additional complications.

The diagnosis can be made by identifying hyphae in a debridement sample of the lesions. During the approach, soft-tissue involvement, bone destruction, or intracranial extension must be evaluated. Skull tomography with simple and contrasted phases is the best study to evaluate bone tissue and data of possible infection in the central nervous system; among the findings, bone erosion, decreased density of the skull base, abscesses, and mastoid involvement should be looked for. To assess whether there is intracranial extension, magnetic resonance imaging is more appropriate. The definitive laboratory diagnosis is by mycological culture, direct microscopy, or histopathology with samples taken directly from the external auditory canal and secretions. In the case presented, the diagnosis could be established by histopathological study of a sample taken directly from the mastoid bone³,⁴.

One of the most feared, but rarest complications of otomycosis is otomastoiditis, described in a small series of cases⁵, where the prolonged use of antibiotics and topical steroids is common. Fungal disease of the temporal bone has been classified into three types: type 1 or non-invasive, Type 2 or with bone invasion (especially in immunocompetent patients), and Type 3 or fulminant angio-invasive (more common in immunosuppressed patients)⁶; The case presented here corresponds to Type 2.

There is no consensus on the most effective agent for the treatment of otomycosis; there are a few publications on its treatment with topical antifungals. It is important to note that some of these studies do not report clinical or mycological details cure rates, or routes of administration. However, everyone agrees on the importance of local mechanical debridement of visible fungal elements and the use of topical or systemic antifungals. Systemic antifungals are reserved for fungal cases of mastoiditis or cerebral extension⁷.

For extrapulmonary forms of aspergillosis, the first treatment option is triazoles, among which the preferred is voriconazole, or alternatively, posaconazole or isavuconazole. If it is not available, or if the patient is intolerant or refractory to such treatments, Amphotericin B is considered the next therapeutic option⁸. New antifungals are in development, such as fosmanogepix, ibrexafungerp, olorofim, and rezafungin, which could be good therapeutic options in the near future⁹.