Fibrous Dysplasia of the Temporal Bone Presenting with Chronic Suppurative Otitis Media: Not All Chronic Ear Discharge is CSOM

Abstract

Dear Editor,
     We read with interest the grand rounds presentation of Alvarez and Uy describing a patient with fibrous dysplasia (FD) of the temporal bone.¹ While the authors provide valuable insights into a rare presentation, we wish to highlight significant concerns regarding the diagnostic framework used in this case.

     Chronic suppurative otitis media (CSOM) is described as a chronic inflammation of the middle ear and mastoid that presents with recurrent ear discharge or otorrhea through a tympanic membrane perforation. The disease usually begins in childhood as a spontaneous tympanic perforation due to an acute infection of the middle ear, known as acute otitis media (AOM), or as a sequelae of less severe forms of otitis media.² It is clear that the infection begins in the middle ear, and is associated with a perforation of the tympanic membrane. One cannot diagnose CSOM in the absence of evidence of a tympanic membrane perforation.

     In the case presented in the article, we note that the diagnosis of chronic suppurative otitis media was first made simply based on the presence of a 1-year history of clear, non-foul-smelling discharge from his left ear associated with intermittent otalgia. This suggests that the physician evaluating the patient thinks that all patients presenting with a long history of otorrhea and otalgia have CSOM. That is an obvious fallacy, as conditions such as (but not limited to) chronic otitis externa, temporal bone carcinoma, a long-standing foreign body in the ear canal, and external canal cholesteatoma can also present with the exact same symptoms. We would like to point this out as a demonstration of the availability bias or availability heuristic. This diagnosis led to the patient being treated for 3 months with management specific to CSOM. It is only later that we learn that there is a hard mass in the external auditory canal. This apparently blocks the external auditory canal, as there is no mention whatsoever of the status of the tympanic membrane. The CT scan, done after the patient did not respond to their medical therapy, shows the presence of a bony lesion whose description ("ground glass") indicates a fibro-osseous lesion such as fibrous dysplasia. It must be noted that this lesion obliterates the external auditory canal and middle ear.

     The medical literature on fibrous dysplasia of the temporal bone describes a sequelae that can explain the patient’s symptoms without resorting to a diagnosis of CSOM. Fandino et al.³ state:

     Fibrous dysplasia involving the temporal bone is an unusual presentation, with the most common associated finding being
conductive hearing loss and stenosis of the external auditory canal (EAC), seen in approximately 8% of patients. Stenosis of the ear canal can result in secondary canal cholesteatoma with extension into the middle ear, leading to conductive hearing loss because of either canal obstruction or erosion/fixation of the ossicular chain.