Cytokeratin Expression in Subungual Squamous Cell Carcinoma

Squamous Cell Carcinoma of the Nail Unit: Review of the Literature

Squamous cell carcinoma of the nail unit (SCCNU) is often misdiagnosed and improperly treated because it mimics a number of other conditions. This review details current knowledge of anatomy, pathophysiology, clinical presentation, diagnosis, and treatment of SCCNU. A heightened clinical awareness is critical to treating SCCNU and preventing development of advanced disease at which time amputation is needed and metastasis may occur. Physicians should consider SCCNU in each case of a nail abnormality unresponsive to topical treatment. For adequate diagnosis and excision of SCCNU, timely and appropriate specialist referral is necessary.

The histopathological feature of the nail isthmus in an ectopic nail

The nail unit has a unique structure. It has been recently proposed that the nail isthmus as a transitional zone between the most distal part of the nail bed and the hyponychium. A 7-year-old Japanese boy presented with an ectopic nail, an additional and independent miniature nail on the digital pulp of the right fifth finger. We studied the expression of a series of keratin in longitudinal specimens and showed the histopathological manifestation in the nail isthmus. This region in the ectopic nail is subdivided into 2 parts: a proximal and narrow part anchored to the nail plate and a distal and wide part with a semihard keratinized structure.