Ungual and Subungual Disease

It may seem surprising to devote a chapter to the nail unit, as the imaging of this structure has developed poorly over time. However, high-frequency transducers have recently allowed accurate imaging of the fingertips with ultrasonography. Now magnetic resonance (MR) imaging of the nail unit is also available thanks to small dedicated surface coils. These new resources could modify the imaging strategy of ungual and subungual diseases. The main indication is the investigation of nail tumors. Neoplasia of the nail area may be benign, but is sometimes aggressive or malignant. A history of trauma, an associated infection or the interposed nail plate may mislead the physician. Deep tumors located under the matrix or the nail bed exert pressure upward and may cause ridging or even anonychia or onycholysis. Thus every suspicious tumor of the nail unit should undergo radiography and a biopsy. An additional imaging modality such as ultrasonography or MR imaging should help in doubtful cases by confirming and accurately locating an ungual or subungual tumor.