Glomus tumors are benign hamartomas that account for 1% to 5% of all soft-tissue tumors of the hand. Painful spasms radiating from the lesion are typical clinical signs. As the pain production mechanism is unclear, we evaluated S100 protein, substance P, and cyclooxygenase-2 expression by immunohistochemistry in glomus tumor samples.

Methods: 

Eight solitary glomus tumors were surgically excised and confirmed histologically by an experienced pathologist. Paraffin-embedded tissues were prepared for immunohistochemistry. The sections were stained with separate polyclonal antibodies for S100, substance P, and cyclooxygenase-2. In three of the tumors, we measured the prostaglandin E₂ concentrations.

Results: 

All samples were positive for S100 protein and cyclooxygenase-2.Substance P was found in five of the eight samples. High prostaglandin-E₂ concentrations were seen in all three samples tested.

Conclusions: 

Cyclooxygenase-2-immunoreactive cells are present in solitary glomus tumors. Since cyclooxygenase-2 produces prostaglandin E₂, which is thought to be a strong vasodilator, the pain could be caused by vasodilation in the glomus tumor, with increased intracapsular pressure.

Clinical Relevance: 

Clinically, non-steroidal anti-inflammatory drugs that block prostaglandin production may control glomus tumor pain. However, considering the possible medication side effects, operative management remains the treatment of choice.