A mistaken identity: rhabdomyosarcoma of the middle ear cleft misdiagnosed as chronic suppurative otitis media with temporal lobe abscess

Abstract

A 5-year-old girl presented with a 3-month history of left side facial palsy, followed sequentially by purulent ear discharge, complete external ophthalmoplaegia and blurred vision. On clinical examination she was febrile with left-sided conductive hearing loss. She was clinically diagnosed to have chronic suppurative otitis media of the unsafe type with petrous apicitis, middle cranial fossa abscess and cavernous sinus involvement. Preliminary CT scan findings were reported as a large left temporal lobe abscess and left otitis media with cholesteatoma. MRI of the brain obtained later corroborated the abnormalities detected on the CT scan. Ten days after admission, a mass was seen protruding from the external auditory canal. A biopsy of the mass was obtained and sent for histopathological examination. Meanwhile, review of the MRI suggested an aggressive neoplasm such as sarcoma/rhabdomyosarcoma. Histopathology clinched the final diagnosis of an anaplastic type of embryonal rhabdomyosarcoma of the middle ear cleft.

Figure 1

A peripherally enhancing lesion involving the left medial temporal lobe and petrous apex, suggesting likelihood of an abscess.

Figure 2

Axial high resolution CT of left temporal bone showing permeative destruction of the left-sided petrous apex. Left middle ear ossicles are surrounded with soft tissue and medially eroded, but there is absence of complete ossicular destruction/disruption.

Figure 3

Clinical photograph of the child showing a mass visible in the left external auditory canal.

Figure 4

T2-weighted axial section of MRI brain shows a heterogeneous, hyperintense lesion measuring 4.7×4 cm (anteroposterior × transverse) in the left petrous temporal bone. This lytic, expansile lesion extends anterosuperiorly to the left temporal lobe region, medially to the left cavernous sinus, posteriorly to the left cerebellopontine angle and left middle cerebellar peduncle, laterally to mastoid air cells and the left external auditory canal.

Figure 5

Coronal and sagittal T1 fat saturated postgadolinium-enhanced MRIs showing heterogeneously enhancing mass lesion with central necrosis that engulfs the carotids with involvement of contiguous structures such as cerebellum, skull base, sphenopalatine fossa, infratemporal fossa, parapharyngeal and visceral space of neck. Central flow voids are visible.

Figure 6

Photomicrograph of tumour cells stained with myogenin (immunohistochemical stain) showing focal positivity, graded+ (×100).

Figure 7

Focal, nuclear positivity for MyoD1 (immunohistochemical stain) in rhabdomyoblastic tumour cells, graded+ (×100).