Extra Digital Glomus Tumor: A Rare Cause for Undiagnosed Chronic Pain in Unusual Sites

Abstract

Glomus tumor, also known as Glomangioma, originates in the neuromyoarterial glomus, a normal arteriovenous shunt abundantly supplied with nerve fibres and fulfilling a temperature-regulating function. The classic location of the glomus tumor is the subungual region, but it can occur elsewhere in the skin, soft tissues, nerves, stomach, nasal cavity, and trachea. There is some question as to whether this is a true neoplasm or simply a normal structure. Glomus tumor constitutes 1% to 5% of all hand tumors. It usually occurs at the subungual region and more commonly in aged women. Its classical clinical triad consists of pain, tenderness, and temperature intolerance, especially cold sensitivity. Glomus tumors are usually benign, but on rare occasions may exhibit an uncertain or malignant behavior as with glomangiosarcoma. In this article, we present a case of a 60-year-old female patient diagnosed with extradigital glomus tumor of the palm of right hand.

Introduction

A glomus tumor is a rare, benign, small vascular tumor that arises from specialized cells normally found within the glomus (Latin for ‘‘ball’’ or spherical mass) body in the reticular dermis. The most common site for glomus tumor development is the distal phalanx, particularly beneath the nails; however, this tumor can be found anywhere on the body. ¹

A glomus body is composed of an afferent arteriole, anastomotic vessel (SucquetHoyer canal), primary collecting vein, intraglomerular reticulum, and capsular portion. ² The glomus tumor was originally considered to be a form of angiosarcoma until the findings demonstrated by Masson ³ in 1924. Multiple nerve fibers can be identified in solitary glomus tumors. Most glomus tumors are benign, but atypical examples exist. The study of atypical glomus tumors by Folpe et al. resulted in a classification scheme that categorizes these lesions as follows: malignant glomus tumor, symplastic glomus tumor, glomus tumor of uncertain malignant potential, and glomangiomatosis. ⁴ Various microscopic types of glomus tumor have been recognized: Three important types are solid, angiomatous, and myxoid variety of glomus tumor. Although glomus tumors are commonly situated at subungal locations but they are rarely also present at extradigital sites also, so glomus tumor must be considered as a differential diagnosis in patients presenting with purple colored, small, compressible, soft, extremely painful nodule at sites other than subungal region of digits. ⁵

Technical investigations are rather nonspecific. Radiography sometimes shows a small impression or sclerotic reaction in the bone adjacent to the tumor, therefore it is important to compare normal and symptomatic sides. Ultrasonography is more specific and it should allow differentiation from ganglia or cysts. Scintigraphy is said to be positive in all cases but is nonspecific. High-resolution MRI is a very sensitive and specific investigative tool. ^6,7 The only effective treatment is excision. Histologically, the tumor consists of well-differentiated clusters of small polygonal cells with dark round nuclei and scanty cytoplasm around small blood vessels.

Case Presentation

History

A 60-year-old female, otherwise healthy, presented with pain and tenderness at the palm of right hand for around 20 years prior but got worse 3 to 4 months before presentation. The patient gave history of seasonal variation getting worse in cold weather, yet no definite palpable masses could be detected.

Patient consulted orthopedic surgeon and neurologist but no specific diagnosis was made. Magnetic resonance imaging revealed a focal lesion at the ventral aspect of the wrist adjacent to the median nerve, appears hypointense on T1 W and hyperintense on T2 W, measured 0.63 × 0.84 cm. A provisional diagnosis of ganglionic cyst was offered (Figure 1).

Figure 1.

Magnetic resonance images.

Surgery

A 3-cm incision was made over the demarcated area in the fourth web space revealed the round nodule involving the common digital artery and nerve (Figure 2).

Figure 2.

Round nodule involving the common digital artery and nerve.

The rounded mass was excised and a microsurgical repair of the common digital artery and nerve “neurorrhaphy” was carried out (Figure 3).

Figure 3.

Excision of the rounded mass followed by microsurgical repair of the common digital artery and nerve.

Pathology

Grossly the specimen was slightly purple in colour of size 0.5 × 0.5 cms. The specimen was sent for histopathology. The histopathological examination showed circumscribed lesion exhibiting proliferation of vascular spaces. Around these vascular spaces, there are round to polygonal cells with distinct cell outlines. Features are consistent with glomangiomyoma and the lesion is completely excised. The patient had significant pain reduction and complete resolution of all symptoms.

Discussion

The presence of glomus tumors in sites other than the digits makes an early and accurate diagnosis difficult. However, following the correct diagnosis, the treatment involves complete surgical excision. ⁸ Diagnosis of a glomus tumor is primarily clinical as imaging techniques, such as plain radiography, magnetic resonance imaging, ultrasonography, and angiography do not yield a specific image of the tumor as they may only show the precise location and size of the tumor. ⁹

Symptoms of glomus tumors are typical and often out of proportion to the size of the neoplasm. Paroxysms of pain radiating away from the lesion are the most common complaint. These episodes may be elicited by changes in temperature, particularly by exposure to the cold, and tactile stimulation even to a minor degree. The mechanism of pain production requires further elucidation, however, identification of nerve fibers containing immunoreactive substance P (SP) in glomus tumors suggests pain mediation through the release of this substance. ¹⁰

The triad of localized pain, cold sensitivity, and point tenderness is characteristic of glomus tumors, although other hand tumors may mimic this clinical presentation. ¹¹ Accurate diagnosis followed by complete excision is regarded as curative for patients with solitary lesions, and recurrence rates for solitary tumors have been found to range from 12% to 33%. ^12,13

Conclusion

Glomus tumors are commonly located in the subungual region of finger. Other sites include palm, wrist, forearm, foot and tip of the spine. It’s a solitary painful lesion composed of glomus cells which are round, regular shaped with a sharply punched out rounded nucleus. Unusual tumor sites and differing clinical symptoms occasionally interfere with the diagnosis and treatment of patients with extradigital tumors. Therefore, it is important to include the glomus tumor in the differential diagnosis of patients with extradigital painful or asymptomatic lesions that are purple in color. Complete surgical excision with pathologic evaluation provides both definitive diagnosis and treatment.