Fig 1. - A well defined erosive change in the distal phalanx of right 4^th distal phalanx.

Fig 2A. - On the longitudinal and transverse US scans, a relatively well defined hypoechoic mass is noted on dorsal aspect of the distal phalanx. Bony erosion by hypoechoic mass is also noted in dorsal aspect of the distal phalanx.

Fig 2B. - On the longitudinal and transverse color Doppler US scans, marked hypervascular flows are noted in the mass.

Differential Diagnosis:

1. vascular leiomyoma - hypervascular but mainly located more superficial and in the papillary dermis and the epidermis.

2. mucoid cyst – anechoic or hypoechoic, but no inner vascular flow.

              classically located in the proximal nail fold and is painless.

              has a pedicle communicating with the distal interphalangeal joint.

Diagnosis: Glomus tumor on the dorsal aspect of the right 4^th finger tip

Discussion:

Glomus tumors are rare, benign lesions. Pathologically glomus tumors are hamartomas developed from the neuromyoarterial glemus body. Glomus bodies regulated blood flow in skin. They are present throughout the body but are highly concentrated in the digits, palms, and soles of the feet.

Seventy-five percent of glomus tumors occur in the hand, especially in the fingertips, and particularly in the subungal area. However, they may affect areas other than the hands and feet. Of all hand tumors, 1% - 2% are glomus tumors. Multiple glomus tumors are present in 2.3% of cases.

 The patients with glomus tumors have pain, point tenderness, and cold sensitivity – so called “classic triad” of glomus tumor. The average age of patients at diagnosis ranges from 30 to 50 years. Men are affected less frequently than are women.

 Sonography shows a small solid homogeneously hypoechoic mass beneath the nail, possibly associated with erosion of the underlying phalangeal bone. The high-velocity flow of intratumor shunt vessels makes this lesion a hypervascular mass at color and power Doppler imaging. This finding is fairly specific for the diagnosis.

Most glomus tumors are highly vascular and show high signal intensity on T2-weighted spine echo MR images and strong enhancement after injection of a contrast media.

Histologic analysis shows vascular channels surrounded by irregularly arranged cuboidal cells. Nerves are found and may account for the pain. The tumor is surrounded by a fibrous capsule.

The only treatment for glomus tumors is surgical removal. The incidence of tumor recurrence after surgical excision ranges from 5% to 50%.

References:

1. Theumann NH, Goettmann S, Le Viet D, Resnick D, Chung CB, Bittoun J, Chevrot A, Drapé JL. Recurrent glomus tumors of fingertips: MR imaging evaluation. Radiology 2002; 223:143-151

2. Opdenakker G, Gelin G, Palmers Y. MR imaging of a subungual glomus tumor. AJR Am J Roentgenol 1999; 172:250-251

3. Drapé JL, Idy-Peretti I, Goettmann S, Wolfram-Gabel R, Dion E, Grossin M, Benacerraf R, Guérin-Surville H, Bittoun J. Subungual glomus tumors: evaluation with MR imaging. Radiology 1995; 195:507-515

4. Fornage BD. Glmus tumors in the fingers: diagnosis with US. Radiology 1988; 167:183-185

5. Van Ruyssevelt CE, Vranckx P. Subungual glomus tumor: emphasis on MR angiography. AJR Am J Roentgenol 2004; 182:263-264

6. Martinoli C, Bianchi S. Hand. In: Bianchi S, Martinoli C eds. Ultrasound of the musculoskeletal system. Berlin, Gemany: Springer; 2007:495-548