A 43-year-old man presents with an extremely painful mass under one of the nails of his right hand. He states that he has become more aware of the mass over the past month. There is a bluish hue to the mass with lifting of the nailbed

b. Glomus tumour typically presents as a mass under the nail with severe pain as the most common feature. The bluish hue is another feature of this rare tumour that can resemble a subungval melanoma. Looking for other signs of melanoma can often be useful in differentiating between these two conditions.