Background Most glomus tumours are located in the digits, especially in subungual areas. Less is known, however, about the clinical characteristics of extradigital glomus tumours.
Objectives The aim of this study was to characterize extradigital glomus tumours and compare their clinical, pathological and immunohistochemical characteristics with those of digital glomus tumours.
Methods We retrospectively reviewed the charts of 110 patients with digital and 42 patients with extradigital glomus tumours, treated at a single centre from 1991 to 2010. We also investigated the immunohistochemical expression of substance P and TRPV1 in the biopsy specimens from patients with digital (n = 5) and extradigital (n = 5) glomus tumours.
Results Compared with patients with digital glomus tumours, patients with extradigital tumours were significantly older (P = 0.009) and showed a significantly greater male predominance (P < 0.001), lower incidence rates of pain (P = 0.019), cold intolerance (P < 0.001) and a higher frequency of the glomangioma subtype (P < 0.001). Extradigital glomus tumours were located most frequently on the upper extremities (n = 25). The most common clinical presentations were solitary purplish papules (n = 10). Only 20% of extradigital glomus tumours were diagnosed correctly by the initial physician. Of 38 evaluable patients, 34 (89.5%) were successfully treated with simple excision without recurrence. Substance P and TRPV1 were expressed moderately to strongly in glomus cells, but there were no differences in their expression between patients with digital and extradigital glomus tumours.
Conclusion Extradigital glomus tumours do not have specific clinical features such as pain, leading to frequent misdiagnosis. To prevent delay in diagnosis or misdiagnosis, it is important to increase awareness of these tumours.