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Compiled By:
Margaret Phillips, M.D.
History:
34-year-old woman complains of pain under the right fourth fingernail for eight years. This pain is notably worse during cold weather.
Exam:
Using the microscopy coil, finger images were performed. Arrows denote a lesion shown with axial T1 (Figure 1), axial T2 (Figure 2), coronal PD STIR (Figure 3), sagittal T2 STIR (Figure 4), sagittal T1 (Figure 5), axial T2 STIR (Figure 6) weighting.
Findings:
A rounded soft tissue nodule at the dorsal lateral distal ring finger tuft measures 2.6x 2.4 x 3.2 mm and has increased T1 and T2 signal with hyperintense signal on STIR.
Diagnosis:
Glomus Tumor.
Discussion:
Glomus bodies function in thermoregulation, being comprised of a specialized arteriovenous anastomoses. They consist of an afferent arteriole that branches into two to four connecting arterioles with thick segments containing concentric smooth muscle cells. These segments have arteriovenous anastomoses connecting with efferent veins. A neurovascular retinaculum regulates blood flow through the anastomoses.
Normal glomus bodies occur in the dermis throughout the body, but in a greater frequency in the digits, palms and soles of the feet. Seventy-five per cent of glomus tumors arise in the hands, particularly the fingertips and especially the subungual regions. They account for 1-2% of all hand tumors, are multiple in 2.3%, and present at an average age range of 20 to 50 years, more frequently in women than men.
Potential locations of glomus tumors, other than subungual fingertips, include the pelvis, wrist, forearm, and foot. The second most frequent site of involvement following the dermis is the subcutaneous tissues. At the tip of the coccyx, these tumors may rarely arise from the glomus coccygeum. Rarely, they arise in deep organs without apparent known normal glomus bodies. Intraosseous lesions are extremely rare.
Clinical symptoms include extreme pain, often out of proportion to the tumor size. Temperature change or minor mechanical stimuli can provoke paroxysms of pain, but discomfort may also occur with no apparent inciting factor. Pain is not predominantly nocturnal nor does it respond to aspirin, unlike osteoid osteoma.
MRI characteristics reflect tumor vascularity with high signal intensity on T2 weighting and intense gadolinium enhancement during the arterial phase with delayed images showing a tumor “blush” that usually increases in size. Erosion of the underlying distal phalanx usually occurs in subungual glomus tumors.
Other lesions that may cause lytic, well-demarcated lesions that are less that 1 cm in size in the distal phalanx include osteoid osteoma, intraosseous epidermal inclusion cyst, and invasive subungual keratoacanthoma of the nail bed.
Glomus tumors are well-circumscribed, soft, tan-gray masses that are easily separable at curettage from soft-tissue or bone. Most glomus tumors are benign; the extremely rare malignant tumors involve soft tissue and have never been reported in an intraosseous location. Treatment of glomus tumors is surgical removal with post-surgical recurrence ranging from 5% to as high as 50%. In one study, MRI showed 54% of recurrent lesions to have a nodule with typical features of a classic glomus tumor, 33% had low or isointense T2-weighted signal compared to the nail bed, and 25% had only faint enhancement after gadolinium, with margins blurred by scar tissue in 9 of 24 cases [1].
Images:
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