| Squamous Cell Lung Cancer with Solitary Subungual Metastasis. |
| Subungual collections of keratotic material are common, with distal separation of the nail from the nail bed. |
| A number of conditions can cause longitudinal melanonychia, but its main importance is that, in some patients, it may indicate the presence of a subungual malignant melanoma. |
| When a solitary nail is involved, the possibility of a subungual tumor such as onychornatricoma or exostosis may be considered. |
| Subungual exostosis begins as a reactive fibrous growth that develops cartilage and ultimately ossifies. |
| Subungual exostosis is an osteoma growing from the terminal phalanx of the great toe. |
