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(5) In a fourth case a 15-year old boy presented with a rhabdomyoma of the left oculomotor nerve being attached to the midbrain.
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A third case report described a rhabdomyoma of the left 8th cranial nerve in a 6-year old boy manifesting in the cerebellopontine angle with growth into the internal acoustic meatus and adhesion to the pons. However, Antoni A and B regions were not seen.
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Histologically, many mature striated fibers were seen, and the tumor was localized within the nerve, which complicated the differential diagnosis of a schwannoma. (6) This tumor infiltrated the facial nerve root and extended from the brainstem to the geniculate ganglion. (7) Another report reviewed a case of a 41-year-old man with a tumor emerging from the right the porus acusticus internus, suggesting a schwannoma. reported a rhabdomyoma of the left trigeminal nerve in a 29-month-old male infant replacing the 5th nerve in the posterior fossa and in the region of Meckel's cave. Reports of rhabdomyomas manifesting at cranial nerves are exceptional, and only 4 cases have been published: Zwick et al. Whereas adult-type extracardiac rhabdomyomas mostly occur in adults older than 40 years, fetal-type tumors tend to occur predominantly in infants and may be associated with autosomal dominant nevoid basal cell carcinoma syndrome (Gorlin syndrome) characterized by PTCH mutations. Among extracardiac rhabdomyomas, adult, fetal and genital types are distinguished with head and neck region as the most common site. Cardiac rhabdomyomas typically occur in young patients and are often associated with tuberous sclerosis. Rhabdomyomas are benign tumors containing striated muscle and are categorized by location as cardiac and extracardiac tumors. A normal variant defect in the anteroinferior aspect of the osseous part of the canal that connects with the temporomandibular joint is known as the foramen tympanicum (foramen of Huschke).Final Diagnosis - Case 775 Final Diagnosis - Fetal type myxoid rhabdomyoma of the vestibular nerveįetal type myxoid rhabdomyoma of the vestibular nerve
PORUS ACOUSTICUS SKIN
The skin of this inner part is directly applied to periosteum, with no subcutaneous tissue present. The roof and upper part of the posterior wall arise from the squamous part of the temporal bone. The anterior wall, floor, and lower part of the posterior wall arise from the tympanic part of the temporal bone . The medial two-thirds is surrounded by bone. Defects in the cartilaginous part of the canal, which allow transmission of infection and malignancy, are known as fissures of Santorini. The lateral one-third is bounded by a fibrocartilaginous tube continuous with the auricle . The external auditory canal is typically 2.5 cm in length and is S-shaped. TerminologyĪs the term external auditory meatus is variably used to refer to the canal itself or the porus acusticus externus (the round lateral opening), it may be better to use the term external auditory canal rather than meatus to avoid potential confusion. The external auditory canal (EAC) or external auditory meatus (EAM) extends from the lateral porus acusticus externus medially to the tympanic membrane.