Diagnosis: Glomus tumor
Treatment: Surgical excision
Discussion: Glomus tumors arise from glomus bodies, which are numerous in the nail bed. These are vascular tumors. Glomus tumors may be locally aggressive, recurrent, and occasionally malignant.
They are more common in females and may be either solitary or multiple. Typically presentation includes severe pain, exacerbated by pressure or temperature change, especially cold.
MR signal correlates with histology. The vascular type demonstrates avid enhancement. These are high on T2-weighted sequences and have multiple vascular lumens.
The cellular type is predominantly composed of epithelioid cells. The paucity of vascular lumens explains the poor enhancement. These can be difficult to detect on MRI and may show small bone erosions.
The mucoid type demonstrates mucoid degeneration and is very high-signal on T2-weighted sequences. These demonstrate mild enhancement.
Glomus tumors typically have well-defined pseudocapsules, but may show small foci of tumor extending into the nearby nail bed. Recurrence rate is high if some tumor is incompletely excised. Occasionally, the tumor is located in the pulp or posterior nail fold.
The bone erosions are similar in appearance to epidermal inclusion cysts.
Keratoacanthoma is a rare, benign, rapidly growing tumor from the most distal part of the nail bed. These begin as a small, painful dome-shaped nodule, which may have a central plug.
Differential diagnoses include subungual squamous carcinoma. Multiple recurrence concerning for glomangiosarcoma, but this is rare.
