What is the clinical significance of the Brown sign in a suspected glomus (glomus tumor) tympanicum tumor in an adult patient?

Brown Sign in Glomus Tympanicum

The Brown sign refers to blanching of a reddish retrotympanic vascular mass when positive pressure is applied during pneumatic otoscopy, and it is a pathognomonic clinical finding that confirms the diagnosis of glomus tympanicum tumor. 1

Clinical Significance and Diagnostic Value

The Brown sign is a highly specific physical examination finding that occurs due to the vascular nature of glomus tympanicum tumors:

• The sign demonstrates the tumor's rich vascular supply and compressibility, distinguishing it from other middle ear masses that would not blanch with pressure 1
• When present, the Brown sign essentially confirms the diagnosis of glomus tympanicum without requiring biopsy, which is contraindicated due to risk of devastating hemorrhagic complications 2

Mechanism and Pathophysiology

The Brown sign occurs because:

• Glomus tympanicum tumors arise from neuroendocrine paraganglion cells of the tympanic plexus (Jacobson's nerve) on the medial wall of the middle ear and are highly vascular benign neoplasms 2
• The primary blood supply comes from the inferior tympanic artery, a branch of the ascending pharyngeal artery, making these tumors extremely vascular and pulsatile 2
• Positive pressure applied during pneumatic otoscopy temporarily compresses the tumor's blood supply, causing visible blanching of the characteristic reddish mass behind the tympanic membrane 1

Clinical Presentation Context

When evaluating a patient with suspected glomus tympanicum:

• The most common presenting symptom is pulsatile tinnitus (present in nearly all cases), followed by conductive hearing loss 3, 4, 1
• Physical examination reveals a vascular retrotympanic mass visible on otoscopy as the primary diagnostic sign 2
• The Brown sign, when elicited, provides immediate bedside confirmation of the vascular nature of the mass 1

Diagnostic Algorithm Following Brown Sign Detection

Once the Brown sign is identified:

• High-resolution CT of the temporal bone without contrast is the first-line imaging modality, showing a soft tissue mass on the promontory without bone erosion of the jugular foramen or carotid canal 2
• MRI with contrast serves as the confirmatory study and is essential for evaluating potential glomus jugulare extension 2
• Biopsy must never be performed due to hemorrhagic risk; imaging alone establishes the diagnosis 2

Critical Pitfall to Avoid

• Do not confuse glomus tympanicum with other vascular middle ear lesions such as high-riding jugular bulb or aberrant carotid artery, which may also present as retrotympanic masses but will not demonstrate the Brown sign 5, 6
• The Brown sign specifically indicates a compressible vascular tumor rather than a displaced major vessel, which would be rigid and non-compressible 6

Treatment Implications

• Surgery remains the treatment of choice for glomus tympanicum, with gross total resection achievable in over 90% of patients 3, 7
• The presence of the Brown sign does not alter surgical approach but confirms the diagnosis preoperatively, allowing appropriate surgical planning and patient counseling 3, 4