The exquisitely painful fingertip – subungual glomus tumours

Abstract

While most painful fingertips have a distinct causal history and/or associated symptoms, some can leave the practitioner at a loss during diagnosis. We present a rare differential that often has an indistinct history, subtle clinical signs and is commonly misdiagnosed, with average diagnosis time reported as 7 years 1. A 25-year-old patient presented with a several-year history of a gradually increasingly painful fingertip, just beneath her nail plate. There was no history of trauma or precipitating event she could recollect. She had been assessed by several practitioners over the years with normal radiology and ineffective neuromodulation, and analgesics offered little effect. On examination, she had a minimal area of slight blue discolouration under her nail plate, which elicited exquisite pain on palpation. This was diagnosed clinically as a subungual glomus tumour based on the symptom of exquisite pain in the fingertip without causal history and the subtle colour discolouration. Treatment was surgical excision under a digital nerve block with removal of the overlying nail plate. The lesion was characterised as a spot directly beneath the nail plate (Figure 1A), with a leash of proximal feeding vessels (Figure 1B). Excision was performed and the resulting defect closed directly (Figure 1C). Histology subsequently confirmed the clinical diagnosis of a glomus tumour, and on postoperative review, she was pain free. Glomus tumours were first described by Wood in 1812, with subsequent histological characterisation by Masson in 1924 2, 3. They are rare, typically benign tumours that arise from the neuromyoarterial structure of the glomus body, a structure believed to serve a thermoregulatory purpose 4. They account for 1–4·5% of hand tumours and are more common in women 1, 5. Although within the hand, the most common site being subungual, glomus tumours may also be found under the nail fold, nail matrix and within the pulp. They characteristically present with a triad of a tender, single, identifiable spot, which is hypersensitive to the cold and causes extreme pain 2. Two clinical tests, with high specificity, are commonly used to aid diagnosis: Love and Heldrith's tests. “Love's test” describes using a small rounded tip, such as a ball point pen nib, to press against the lesion eliciting exquisite pain. “Heldrith's test” involves raising the arm above heart level to exsanguinate the limb prior to inflation of a blood pressure cuff over the upper arm. The patient may experience symptomatic relief during this phase. The pressure cuff is then released, and pain is instantly elicited in the fingertip with a positive test 1, 6. Magnetic resonance imaging and ultrasound scanning have been shown to play a role in delineating the extent and location of the tumour, although this is not clinically indicated 7. In summary, when presented with a patient who has an extremely painful fingertip and an unclear history, never forget the rare but debilitating glomus tumour and refer the patient on to a hand surgeon for further management.