Summary

A Glomus Tumor is a rare, benign neoplasm of the Glomus Body (a specialized arteriovenous anastomosis involved in thermoregulation). While they can occur anywhere, 75% are located in the hand (subungual), but they also occur in the foot. They are famous for causing disproportionate, excruciating pain relative to their tiny size (<5mm). The diagnosis is strictly clinical, relying on the Classic Triad: 1) Severe paroxysmal pain, 2) Pinpoint tenderness (Love's Test), and 3) Cold intolerance. Treatment is surgical excision, which is curative. [1,2,3]

Key Facts

• The Thermostat: The Glomus body controls blood flow to the fingertips/toes to regulate heat. This explains why the tumor hurts so much in the cold (vasoconstriction squeezes the mass).
• The Size: These tumors are tiny (often 2-3mm). They are often invisible to the naked eye and sometimes even invisible on MRI. You have to hunt for them.
• The Blue Dot: If the tumor is large enough, you might see a faint blue/purple discolouration under the nail plate.

Clinical Pearls

"Love's Pin Test": The most sensitive test. Take the head of a pin (or a paperclip) and press gently on the nail. You can map the tumor to the millimeter. Pressing 1mm away is painless; pressing on the spot causes the patient to jump.

"Hildreth's Sign": Exsanguinate the digit and apply a tourniquet. The pain disappears. Release the tourniquet, and the pain returns with a rush of blood. (Sensitivity 92%).

"It's not in your head": Patients are often misdiagnosed for years as having "psychosomatic pain" because no one can see a lump. Validating their pain is the first step in treatment.

                 PAINFUL NAIL
                      ↓
             LOVE'S TEST POSITIVE?
            ┌──────────┴──────────┐
           YES                   NO
      (Supsicious)           (Observe)
           ↓
        MRI SCAN
      (High Res T2)
           ↓
     LESION FOUND?
      ┌────┴────┐
     YES        NO (But high clinical suspicion)
      ↓         ↓
    SURGERY   REPEAT MRI / EXPLORE
   (Excision)

Excision Techniques

Complete removal is required.

1. Trans-Ungual Approach (Subungual)

• Indication: Central lesions.
• Technique:
  • Remove nail plate.
  • Incise nail bed longitudinally over the blue spot.
  • Shell out the tumor (pearly, encapsualted).
  • Repair nail bed with 6-0 absorbable.
  • Replace nail plate as splint.
• Outcome: High cure rate. Risk of nail deformity.

2. Lateral Subperiosteal Approach

• Indication: Lateral/Matrix lesions.
• Technique:
  • Elevate the lateral nail fold.
  • Access the tumor from the side, sparing the nail bed incision.
• Benefit: Better cosmetic nail outcome.

MRI Sensitivity

• Al-Qattan et al: Reported that MRI can miss very small tumors (<2mm). If clinical signs (Love/Hildreth/Ice) are strongly positive, surgical exploration is justified even with a negative MRI.

Surgical Approach

• Garg et al: Trans-ungual approach provides better visualization and lower recurrence rates compared to lateral approaches, despite the higher risk of nail dystrophy. Seeing the tumor is the priority.

The Lump

You have a tiny "hot water pipe" under your nail that has overgrown. It is full of nerves, which is why even a light touch hurts so much.

The Fix

We have to take the nail off and cut the tiny lump out.

• "Will the nail grow back?" Yes. We put the old nail back on as a bandage. A new one grows in 6 months.
• "Will the pain go?" Instantly. The relief is dramatic.

Q1: What are the three classic symptoms of a Glomus Tumor? A:

1. Paroxysmal Pain.
2. Pinpoint Tenderness.
3. Cold Intolerance.

Q2: Describe Hildreth's Sign. A: Pain relief when a tourniquet is applied to the proximal digit (ischemia), and return of pain ("rush") when the tourniquet is released. It differentiates glomus tumors from neuromas or other pathology as glomus tumors are blood-flow dependent.

Q3: What is the risk of leaving small satellite nodules behind? A: Recurrence. Glomus tumors can be multicentric (especially in Glomangiomatosis). The surgeon must inspect the cavity carefully for extra pearls.

Q4: Histopathologically, what cell type characterizes this tumor? A: The Glomus Cell. A modified smooth muscle cell of the Sucquet-Hoyer canal. They are round, uniform, and surround vascular spaces.

(End of Topic)