Diagnosis: Subungual glomus tumor
Glomus tumor is a rare vascular neoplasm derived from the cells of the glomus body, a specialized arteriovenous shunt involved in temperature regulation. Glomus bodies are most abundant in the extremities, and 75% of glomus tumors are found in the hand.1 The most common location is the subungual region, where glomus bodies are highly concentrated.
These lesions are typically benign, although a malignant variant has been reported in 1% of cases.1,2 Glomus tumors are most common in adults 30 to 50 years of age, with subungual tumors occurring more often in women.3 The majority of glomus tumors are solitary and less than 1 cm in size.2,4 Multiple tumors may be familial and tend to occur in children.2,4
In an analysis of 43 patients with glomus tumors, only 19% of referring practitioners and 49% of hospital practitioners made the correct diagnosis.Patients with subungual glomus tumors present with intense pain that they may describe as shooting or pulsating in nature.
The pain may be spontaneous or triggered by mild trauma or changes in temperature—especially warm to cold. The classic triad of symptoms includes pinpoint tenderness, paroxysmal pain, and cold hypersensitivity. 3,4 The glomus tumor may appear as a focal bluish to erythematous discoloration visible through the nail plate, and in some cases the tumor may form a palpable nodule. Nail deformities such as ridging and distal fissuring occur in approximately one-third of patients.4
Longitudinal erythronychia, as seen in our patient, results when the glomus tumor exerts pressure on the distal nail matrix. This force leads to a thinning of the nail plate and the formation of a groove on the ventral surface of the nail. Swelling of the underlying nail bed with engorgement of vessels produces the red streak that is seen through the thinned nail.5 And, because the affected portion of the nail is fragile, it tends to split distally.
Longitudinal erythronychia with nail dystrophy involving multiple nails is also seen in inflammatory diseases, such as lichen planus and Darier disease, due to multifocal loss of nail matrix function.5