My Instructive Nail Case

The speaker presents a case study at a nail symposium involving a 56-year-old man with big toenail dystrophy, ultimately diagnosing it as onychometric. An examination revealed multiple cavities in the nail plate, leading to full nail aversion where a tumor was found attached to the thickened nail. Histopathological analysis showed a fibroblastic tumor associated with neural metrics-like epithelium, solidifying the diagnosis of onychometric. To further understand the tumor's molecular characteristics, single cell RNA sequencing was performed, yielding critical insights into the tumor's cellular makeup. The study found elevated levels of RSPO4, a secreted protein involved in Wnt signaling and crucial for nail formation, particularly in the fibroblasts associated with the tumor. The findings propose the novel concepts of onicodermis and onico fibroblast, indicating their significant roles in nail formation and pathology. The speaker concludes with the take-home message that onychometric is a nail-specific tumor originating from onico fibroblast, where Wnt signaling is implicated in its pathogenesis.