Mammalian glomus tumor: contribution of nerve ultrasound

Glomus tumor is an enigmatic tumor derived from proliferation of the normal capsular–neural glomus apparatus of the skin. 1 This type of tumor is usually painful and may be solitary or multiple. 2 Tenderness and cold FIGURE 1.Photos of the patient:(A) tongue deviation, (B) a moderate motor deficit in flexion of the terminal phalanx of the right thumb due to impairment of the anterior interosseous nerve innervating the flexor pollicis longus muscle, and (C) right scapular winging due to impairment of the long thoracic nerve innervating the serratus anterior muscle. Abbreviation:US, ultrasound Key words:glomus tumor; imaging; magnetic resonance; pain; rehabilitation; ultrasound Correspondence to:L. Padua; e-mail: lpadua@rm.unicatt.it VC 2016 Wiley Periodicals, Inc. 336 Letters to the Editor MUSCLE & NERVE August 2016 hypersensitivity are other common symptoms with marked impairment of quality of life. It usually occurs in men from the fourth to the seventh decade. 3 Localization of this tumor is highly variable, with major prevalence at subungual sites. The low frequency of glomus tumor and the heterogeneous presentation often delay diagnosis. 4 An atypical anatomical site and the usually small size of the tumor may further complicate diagnosis. 5 Nerve ultrasound (US) is considered an efficient tool for diagnosis of nerve diseases. 6–8 Because US is less expensive, less invasive, and less time-consuming than magnetic resonance imaging, nerve US may become the first choice for evaluation of peripheral nerve diseases. 9 Recent studies have emphasized that US may play a crucial role, not only in the diagnosis but also in preoperative localization of glomus tumor, facilitating excision of the mass. 2,3,10 Currently, MRI is frequently recommended for preoperative assessment, but it may be less sensitive for detection of tumors <3 mm in diameter. 11 According to the literature, knowledge of the exact site and size of the glomus tumor before surgical intervention appears to improve results and reduce recurrence rates. 12 We report the case of a man who had suffered for several years from disabling neuropathic pain and in whom US was able to identify a glomus tumor. A 69-year-old man was referred to our neurophysiological laboratory because of long-lasting, superficial, very severe pain in the right breast, which was not responsive to drugs (including antiepileptics, antidepressants, and opioids). He had been previously diagnosed with herpes zostersine herpete. After clinical and neurophysiological examination (needle electromyography of paravertebral muscles and sensory nerve conduction studies of hand), MRI of cervical spine and chest was performed and showed no pathological findings. US was performed twice over the painful area, using a 10–18-MHz linear probe. The first US evaluation did not identify any abnormality. The second US evaluation, which was done more carefully and with better accuracy, showed a very small, hypoechoic, round, subcutaneous structure with a 15-mm 2 area. Diagnoses of neuroma/ neurofibroma or glomus tumor were suspected. Perilesional infiltration with methylprednisolone (1 ml of Depo-Medrol 40 mg/ml solution) and lidocaine (1 ml of 2% 200 mg/10 ml solution) provided partial relief of pain. The patient subsequently underwent surgical excision of the lesion, which turned out to be a glomus tumor. Immediately after surgery, he reported complete pain relief with full recovery of quality of life. Subsequently, the patient reported that he, his daughter, father, and brother were also affected by neurinoma. Typically, glomus tumor appears as a homogeneous, hypoechoic lesion on US and hyperintense T2-weighted MRI image with high-contrast enhancement. 13 MRI did not show any abnormality in the patient described in this report. This case confirms the utility of accurate US to depict a very small nerve lesion, which provides important information for diagnosis and preoperative localization. The morphologic information obtained allowed for a complete excision of the mass along with complete pain relief.