A. Benign glomus tumor
The clinical presentation and associated symptomatology is classic, and nearly pathognomonic, for a benign glomus tumor. The latter represents a proliferation of normal neuromyoarterial structures (glomus bodies) that physiologically aid in temperature homeostasis. Solitary glomus tumors, which represent over 90% of such lesions, are sporadic in nature, arise during adulthood, favor the upper extremities, and are more common in women. Some 70% to 90% of these tumors arise in the subungual tissue due to the high concentration of glomus bodies in that anatomical location. When glomus tumors arise under the nail, they most often appear as a small red or purple-colored macule; if tumors grow sufficiently large, there may be distortion of the nail plate. Glomus tumors may be subcategorized into three histological variants on the basis of the predominant tumor component: solid glomus (most common), glomangiomas, or glomangiomyomas. Gastric and other visceral glomus tumors have occasionally been reported in the medical literature, but remain uncommon. Malignant glomus tumors do exist, but these are exceedingly rare, and are visibly and palpably infiltrative.
As is true of virtually all neoplasms, histologic examination remains the gold standard for the diagnosis of glomus tumor. Nonetheless, several clinical “tests,” with sensitivity and specificity of over 90%, can be applied to help establish this as a probable diagnosis. These include: the Love test (probing with a pinpoint object reproduces the pain), the Hildreth test (application of a tourniquet reduces pain), the cold test (pain is provoked by application of an ice cube to the suspected tumor site), and the Joseph–Posner test (ethyl alcohol(Drug information on alcohol) spray to the affected area provokes pain).
Although a variety of alternative treatment modalities have been noted, the therapy of choice is meticulous and complete excision.[1,5,7] Since incomplete removal will almost certainly lead to tumor regrowth and symptom recurrence, presurgical and/or intraoperative evaluation of tumor extent and localization is recommended. This may be accomplished by either color duplex Doppler ultrasonography or magnetic resonance imaging, both of which can precisely identify tumors as small as 2 mm.[8,9] Standard digital radiographs may show subtumoral bone erosion, but are typically not useful to help precisely plan the anticipated surgical intervention. The most common surgical approach is the transungual approach, during which the nail plate is removed and the portion of the nail bed bearing the tumor is incised longitudinally; after tumor removal, the nail bed is repaired to minimize postoperative nail deformity.[5-7,10]
Despite the fact that glomus tumors have a prototypical presentation, one must never be complacent about this diagnosis. On occasion, a subungual squamous-cell carcinoma (in situ or invasive) or subungual malignant melanoma (especially an amelanotic one) may closely mimic a glomus tumor. When in doubt, a transungual punch biopsy in advance of definitive surgery may be in order.
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3. Samaniego E, Crespo A, Sanz A. Key diagnostic features and treatment of subungual glomus tumor. Actas Dermosifiliogr. 2009;100:875-882.
4. Folpe AL, Fanburg-Smith JC, Miettinen M, et al. Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors. Am J Surg Pathol. 2001;25:1-12.
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8. Chen SH, Chen YL, Cheng MH, Yeow KM, Chen HC, Wei FC. The use of ultrasonography in preoperative localization of digital glomus tumors. Plast Reconstr Surg. 2003;112:115–119.
9. Kim SW, Jung SN. Glomus tumor within digital nerve: A case report. J Plast Reconstr Aesthet Surg. 2011;64:958-960.
10. Song M, Ko HC, Kwon KS, Kim MB. Surgical treatment of subungual glomus tumor: a unique and simple method. Dermatol Surg. 2009;35:786-791.
11. Baran R. The red nail—always benign? Actas Dermosifiliogr. 2009;100 (Suppl):106-113.