What could be the cause of and how to manage a 2-year history of chronic throbbing pain on the right side of a patient's thumb near the nail at the 2 o'clock position, without signs of infection, inflammation, or trauma, and what treatment options are available?

Chronic Lateral Thumb Pain Near Nail Without Inflammation

This patient most likely has either a glomus tumor or chronic nail unit trauma/deformity causing localized neuropathic pain, and requires immediate referral to dermatology or hand surgery for definitive diagnosis, as nail pain without visible inflammation lasting two years warrants investigation for occult pathology including neoplasm. 1

Critical Diagnostic Considerations

The "2 o'clock position" lateral location is highly specific and concerning for:

• Glomus tumor: These benign vascular tumors classically present as severe, paroxysmal throbbing pain localized to one specific area of the nail unit, often triggered by cold or pressure, and may be invisible on examination 1, 2
• Occult nail deformity or trauma: Chronic repetitive microtrauma can cause localized neuropathic pain without visible changes 1
• Early inflammatory arthritis: Metacarpophalangeal or interphalangeal joint involvement can refer pain to the nail area, though typically presents with some joint findings 3

Immediate Diagnostic Workup

Physical examination must include:

• Pinpoint palpation with a blunt probe to reproduce exact pain location - positive "Love's pin test" suggests glomus tumor 1
• Cold sensitivity testing - immerse thumb in ice water; exquisite pain reproduction is pathognomonic for glomus tumor 1
• Examination of all 20 nail units to identify systemic patterns 2
• Assessment of nail plate for subtle ridging, splitting, or color changes that may indicate chronic trauma 1, 2
• Palpation of metacarpophalangeal and interphalangeal joints for synovitis or crepitus 3

Imaging studies required:

• MRI of the thumb is the gold standard for detecting glomus tumors, which may be <2mm and invisible clinically 1
• Plain radiographs to exclude bony pathology or arthritis 3

Management Algorithm

If Glomus Tumor Suspected (localized point tenderness + cold sensitivity):

• Urgent referral to hand surgery or dermatology for surgical excision - this is curative and the only definitive treatment 1
• Do NOT attempt conservative management, as these tumors do not respond to medical therapy 1

If No Tumor Identified:

• Trial of neuropathic pain medication: Gabapentin titrated to 2400mg daily in divided doses for localized neuropathic pain 4
• Topical capsaicin 0.035% applied to painful area for neuropathic pain relief 5
• Thumb spica splinting to immobilize and reduce mechanical irritation 6

If Inflammatory Arthritis Suspected:

• Corticosteroid injection into affected joint may provide diagnostic and therapeutic benefit 3
• NSAIDs for anti-inflammatory effect 3

Critical Pitfalls to Avoid

• Never dismiss chronic localized nail pain as "nothing" or purely psychological - this presentation pattern strongly suggests organic pathology requiring investigation 1, 2
• Do not delay imaging - glomus tumors are frequently missed for years because they are not visible, causing unnecessary suffering 1
• Do not empirically treat for fungal infection - the absence of nail plate changes, the localized nature, and throbbing quality make onychomycosis extremely unlikely 7
• Avoid assuming "no findings" means no disease - many painful nail conditions have minimal or no visible changes 1, 2

Referral Indications

Immediate referral to dermatology or hand surgery is warranted because:

• Pain duration >2 years without resolution suggests structural pathology 1
• Highly localized pain at specific position is characteristic of glomus tumor 1
• Nail unit tumors require specialist evaluation and often biopsy 2
• Chronic pain significantly impairs quality of life and function 2