|Ahead of print
Rhabdomyosarcoma of middle ear: No longer a radiological surprise!
Shilpa Sankhe1, Ayush Jain1, Subhash Yadav2
1 Department of Radiology, Seth GS Medical College and KEM Hospital, Mumbai, Maharashtra, India
2 Department of Pathology, Tata Memorial Hospital, Mumbai, Maharashtra, India
|Date of Submission||29-May-2020|
|Date of Decision||27-Aug-2020|
|Date of Acceptance||01-Oct-2020|
|Date of Web Publication||02-Jul-2021|
Department of Radiology, Seth GS Medical College and KEM Hospital, Parel, Mumbai 400012, Maharashtra.
Source of Support: None, Conflict of Interest: None
| Abstract|| |
An eight-year-old girl presented to the outpatient department with a history of decreased hearing from the right ear, bloody ear discharge, and facial deviation to the left side. On clinical examination, she was afebrile with conductive right-sided hearing loss. With a primary diagnosis of unsafe type of chronic suppurative otitis media in mind, computed tomography scan of the temporal bone was performed which showed an aggressive destructive lesion in the petrous temporal bone. Magnetic resonance imaging was then performed to look for soft tissue extension and vascular involvement. Based on the clinical and imaging findings, she was diagnosed as a high-grade neoplasm of the right temporal bone, such as rhabdomyosarcoma. Histopathology finally confirmed the diagnosis of an embryonal type of rhabdomyosarcoma of the middle ear cleft.
Keywords: Embryonal rhabdomyosarcoma, middle ear cleft, tadpole cells, temporal bone
An 8-year-old girl presented with a 6-week history of decreased hearing from the right ear, bloody ear discharge, and facial deviation to the left side. High-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) scans of the temporal bone were performed, which showed an aggressive destructive lesion centered on the right petrous apex [Figure 1] and [Figure 2]. These findings in a pediatric patient were suggestive of a high-grade neoplasm centered in the petrous temporal bone. Biopsy of the mass showed a primitive tumor [Figure 3] composed of ovo-spindloid cells admixed with chronic inflammation. On immunohistochemistry (IHC), these were positive for desmin, focally for myogenin, and negative for SMA (a marker for smooth muscle) and AE1/AE3 (epithelial marker). Hence, a diagnosis of embryonal rhabdomyosarcoma (RMS) of the middle ear cleft was made. Few rounded pulmonary nodules were seen on chest CT, suggestive of metastatic disease. The patient was not a surgical candidate, and hence was treated with chemoradiation.
|Figure 1: Axial (A and B) and coronal (C and D) sections of the HRCT temporal bone showing moth eaten destruction of the right petrous apex (black arrow) with involvement of the bony carotid canal. Post contrast images (B and D) show mild homogenous enhancement. Mastoid cavity is filled with fluid. The ear ossicles were preserved (not shown). Note that the epicenter of the lesion is seen in the petrous apex|
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|Figure 2: Axial T2 (A) and coronal FLAIR (B) images showing ill-defined isointense soft tissue (blue asterisk) in the petrous apex extending into the external auditory meatus. Axial Non EPI Diffusion (C) showing no restricted diffusion. Axial Pre and post contrast T1 images (D and E) showing significant post contrast enhancement (blue dashed arrow). Axial highly T2-weighted image (F) depicting the encasement of the right petrous ICA (orange arrow) |
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|Figure 3: (A) Scanner view showing a subepithelial primitive tumor arranged in sheets. Overlying squamous epithelium appears unremarkable. (B) High-power view (HE 400x) shows round to oval cells with hyperchromatic nuclei and indistinct cell border. Immunohistochemistry shows strong positivity for desmin (C) and myogenin (D) in these primitive cells|
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The clinical presentation of patients with middle ear RMS mimics that of chronic suppurative otitis media (CSOM) with a few case reports describing the erroneous clinical diagnosis of CSOM. Facial palsy early in the disease is an important pointer towards a neoplasm rather than CSOM and involvement of cranial nerves in middle ear RMS is an indication of advanced disease.
The histological appearances of the tumor vary with rhabdoid component showing cells with eccentric nuclei and abundant eosinophilic granular cytoplasm. On IHC, rhabdomyoblastic differentiation is seen with desmin, myogenin, and myoD1 which are markers of skeletal muscle differentiation.
In summary, the pointers toward neoplasm in the middle ear cleft include early facial nerve involvement, serosanguinous ear discharge, and an aural mass. Imaging and histopathology are vital for the diagnosis and follow-up.
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Conflicts of interest
There are no conflicts of interest.
| References|| |
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[Figure 1], [Figure 2], [Figure 3]