Glomus Tumors

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Introduction & Epidemiology - Tumor Tidbits

  • Definition: Highly vascular, typically benign neoplasms (paragangliomas).
  • Origin: Neural crest cells (paraganglia) along glossopharyngeal (CN IX) & vagus (CN X) nerves within the temporal bone.
  • Common Types:
    • Glomus Tympanicum: Middle ear origin (Jacobson’s nerve on cochlear promontory).
    • Glomus Jugulare: Jugular foramen/bulb origin.

⭐ Glomus tumors are the most common benign tumors of the middle ear.

  • Prevalence: Rare overall. Female predominance (F:M ≈ 3:1). Peak incidence 40-50 years.
  • Genetics: Familial in ~10-50%; linked to Succinate Dehydrogenase (SDH) gene mutations (e.g., SDHD, SDHB). Glomus tumor in middle ear

Clinical Presentation - Symptom Symphony

  • Hallmark: Pulsatile tinnitus (often earliest).

    ⭐ Pulsatile tinnitus is the hallmark symptom of glomus tumors.

  • Key Otoscopic Signs:

    • Rising Sun Sign: Reddish-blue vascular mass behind intact TM (Glomus Tympanicum). Glomus Tympanicum "rising sun" sign
    • Brown's Sign: Blanching of mass with positive pressure (pneumatic otoscopy).
    • Aquino's Sign: Blanching of mass with ipsilateral carotid artery compression.
  • Glomus Tympanicum vs. Glomus Jugulare:

    FeatureGlomus TympanicumGlomus Jugulare
    TinnitusPulsatilePulsatile
    Hearing LossConductive (CHL)CHL / SNHL / Mixed
    Key Sign'Rising sun' behind TMOften involves CN palsies
    CN PalsiesRareIX-XII (Vernet's: IX,X,XI).
    - IX: Dysphagia
    - X: Hoarseness
    - XI: Shoulder drop
    - XII: Tongue deviation

📌 Mnemonic for Jugulare CNs (IX-XII): "Jugular foramen is home to 9, 10, 11, 12 nerves."

Diagnosis & Imaging - Detective Work

  • Otoscopy:
    • Reddish-blue pulsatile mass behind intact TM (Rising Sun sign).
    • Brown's sign: Blanching/↓pulsation on +ve pressure (pneumotoscopy).
  • Audiometry: Conductive (CHL), mixed (MHL), or sensorineural (SNHL) hearing loss.
  • Imaging:
    • HRCT (Temporal Bone): Phelp's sign (tumor mass at jugular foramen), details bony erosion. Axial CT showing glomus tumor with Phelps sign
    • MRI (Gadolinium): 'Salt & pepper' appearance (T1WI+C: flow voids, hemorrhage); defines extent, intracranial spread.
    • Angiography: 'Mother-in-law' sign (early blush, late retention); identifies feeders; pre-op embolization.
  • ⚠️ Biopsy: Generally contraindicated: high vascularity, significant bleeding risk.
  • Biochemical Tests: If functional suspected: 24-hr urine VMA, metanephrines; plasma free metanephrines.

⭐ The "salt and pepper" appearance on T1-weighted MRI with contrast is characteristic of paragangliomas.

Staging & Management - Battle Plan

Fisch Classification:

  • Glomus Tympanicum (Middle Ear):
    • Type A: Tumor limited to middle ear cleft.
    • Type B: Tumor involving tympanomastoid compartment.
    • Type C: Tumor involving infralabyrinthine compartment & petrous apex.
    • Type D: Intracranial extension < 2 cm.
  • Glomus Jugulare (Jugular Foramen):
    • Type A: Tumor limited to jugular bulb, middle ear, mastoid.
    • Type B: Tumor extending to infralabyrinthine compartment, petrous apex.
    • Type C: Tumor extending into petrous apex, carotid canal, foramen lacerum.
    • Type D: Intracranial extension (D1: < 2 cm; D2: > 2 cm).

Management Options:

  • Observation: Small, asymptomatic, elderly/comorbid patients.
  • Surgery: Mainstay treatment.
    • Pre-operative embolization: Often 24-48 hours prior.
    • Approaches: Transcanal, transmastoid, infratemporal fossa.
  • Radiotherapy (RT): Stereotactic Radiosurgery (SRS) / Stereotactic Radiotherapy (SRT).
    • Primary (elderly/unfit/recurrent) or adjuvant.

⭐ Pre-operative embolization is often performed 24-48 hours before surgery for vascular glomus tumors to reduce intraoperative bleeding.

High‑Yield Points - ⚡ Biggest Takeaways

  • Most common benign tumor of the middle ear; arises from paraganglia.
  • Pulsatile tinnitus (synchronous with pulse) is the classic symptom.
  • "Rising sun" sign: Reddish vascular mass behind the tympanic membrane.
  • Brown's sign: Blanching of mass with pneumatic otoscopy (positive pressure).
  • Phelp's sign (CT): Assesses bony erosion, e.g., jugular foramen.
  • Aquino's sign: Blanching with ipsilateral carotid artery compression.
  • Surgery is primary treatment; radiotherapy for specific cases.

Practice Questions: Glomus Tumors

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Flashcards: Glomus Tumors

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_____ otosclerosis is the most common type of otosclerosis.

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