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Print version ISSN 0365-0596
An. Bras. Dermatol. vol.85 no.2 Rio de Janeiro Mar./Apr. 2010
IMAGING IN DERMATOLOGY
Laura de Sena Nogueira MaeharaI; Eugenia Maria Damasio OheII; Mauro Yoshiaki EnokiharaIII; Nilceo Schwery MichalanyIV; Sergio YamadaIV; Sergio Henrique HirataIII
Resident Physician - Federal University of Sao Paulo - UNIFESP - Sao Paulo (SP),
IISpecialist Physician - Federal University of Sao Paulo - UNIFESP - Sao Paulo (SP), Brazil
IIIPh.D. - Federal University of Sao Paulo - UNIFESP - Sao Paulo (SP), Brazil
IVProfessor, M.S. - Federal University of Sao Paulo - UNIFESP - Sao Paulo (SP), Brazil
Surgery is the best treatment for glomus tumors. Sometimes this can be a challenging procedure because, despite being a well-defined tumor, its visualization can be difficult. The use of nail bed and matrix dermoscopy facilitates the diagnosis and aids in the localization and demarcation of the tumor. It is a simple and low-cost procedure that does not involve additional risks to the patient who will undergo surgery.
Keywords: Dermoscopy; Glomus tumor; Nail diseases
For a long time, nail alterations were not viewed as a priority by doctors of various specialties. However, a growing interest in the diagnosis and treatment of nail disorders1 transformed an area previously neglected by practicing physicians and researchers into an attractive and necessary field of knowledge to dermatologists.
Glomus tumors represent from 1 to 5% of soft tissue tumors of the hand. They are painful benign hamartomas with increased sensitivity to cold. They originate from the normal myoarterial apparatus and are constituted by an afferent arteriole and vascular channels with endothelial cells, surrounded by cuboidal cells.2,3 Nearly 75% of glomus tumors are localized in the hands, particularly in the nail apparatus. These tumors present as purple-blue subungual nodules. They rarely cause changes in color or deformity in the nail plate.
Diagnosis of glomus tumor is accomplished through clinical and imaging examination.
Clinical analysis involves the performance of the following procedures:2
Loves pin test: allows the identification of pain in the lesion, being positive if the patient withdraws the finger.
Hildreths test: it is the repetition of the previous test after the use of a medical tourniquet in this case pain is absent.
Cold sensitivity test: greater pain intensity with temperature drop.
Nail plate dermoscopy.
Glomus tumors are often small and rarely palpable. Thus, clinical examination is insufficient to determine their precise localization. 4,5,6
Imaging exams help the precise localization of tumors and the pre-surgical evaluation of their size. These are very important data in the choice of the surgical approach.7 Ultrasound often shows hypoecogenic lesions with up to 3 mm of diameter; however, it is an operator-dependent examination. 5 Magnetic resonance is more sensitive and shows the extension of the lesion. Its disadvantage, in addition to cost, is low specificity (50%, producing similar images in cases of mucous cyst, hemangioma, epithelial inclusion, and giant-cell tumor of the tendon sheath).6,8 Its greatest advantage is its high sensitivity (90%), especially if high resolution is used, detailing the characteristics of the tumor and allowing the diagnosis while the tumor is still small.6,7
Nail plate dermoscopy can reveal the presence of vascular structures; however, sometimes these structures can be discreet or absent (Figure 1).
Once the diagnosis has been accomplished, tumor excision surgery is the definitive treatment, with immediate post-surgical pain relief. Direct excision is the standard procedure.2 There are alternative techniques involving lateral incision which allow tumor exposure without nail plate avulsion. This reduces the chance of post-surgical deformity, but it increases the possibility of incomplete tumor resection.2,5
The treatment of glomus tumors can be a challenge because, despite being a well-defined tumor, sometimes its visualization is difficult. Recidivation often occurs within weeks and it is a consequence of incomplete tumor excision, which is caused by the difficulty of distinguishing between normal and affected tissue.
To overcome these difficulties, we suggest the performance of bed and matrix nail dermoscopy, 9,10 before tumor exeresis. This procedure is performed during the intra-surgical period, after anesthetic block and careful avulsion of the nail plate. The use of tourniquets is recommended to avoid bleeding that may difficult the visualization of the structures to be examined. The tourniquet should not be too tight because ischemia can prevent the visualization of vascular structures. It is possible to examine the entire nail bed and matrix without contact with the area of surgery, preserving asepsis conditions, with polarized light dermoscopy.
This technique aids in tumor localization and in the visualization of the vascular pattern of the lesion (Figure 2), suggesting the diagnosis of glomus tumor. Especially when the tumor is not encapsulated, the use of dermoscopy facilitates the delimitation of surgical margins in the intra-surgical period (Figure 3). It also allows, after lesion exeresis, the visualization of other residual macroscopic tumor foci in the nail apparatus (Figure 4).
Dermoscopy does not replace histopathologic examination, which should always be performed. The study of the nail bed and matrix reveals non-observable aspects when the nail plate is interposed between the lesion and the dermatoscope. It is a simple and low-cost procedure that assists in the diagnosis and lesion exeresis and that does not involve additional risks to the patient who will undergo surgery.
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10. Hirata SH, Yamada S, Almeida FA, Tomomori-Yamashita J, Enokihara MY, Paschoal FM, et al. Dermoscopy of the nail bed and matrix to assess melanonychia striata. J Am Acad Dermatol. 2005;53:884-6 [ Links ]
Received on January
Approved by the Peer Review Board and accepted for publication on January 29th, 2010.
Conflict of interest: None
Financial funding: None
* Trabalho realizado Departamento de Dermatologia da Universidade Federal de São Paulo