Monodactylous Longitudinal Nail Plate Changes: Differential Diagnosis and Work-up

The discussion led by a faculty member at the University of Miami focuses on monodactylous longitudinal nail plate changes, emphasizing their significance as potential indicators of nail matrix tumors, including malignant ones. The presentation outlines three common tumors associated with nail changes: longitudinal melaninicia, longitudinal erythronychia, and longitudinal pachonychia, detailing their visual characteristics and differential diagnoses. Melaninicia can indicate melanocytic neoplasms such as melanoma or, importantly, squamous cell carcinoma, particularly linked with high-risk HPV. Longitudinal erythronychia is often due to onychopapilloma, highlighted for its commonality yet noteworthy for its atypical presentations, especially in darker skin tones. Pachonychia is characterized by thickened nails and has a narrower differential diagnosis primarily involving onychomatricoma and various carcinomas. The speaker emphasizes the necessity for clinicians to maintain a high index of suspicion for underlying pathologies, including squamous cell carcinoma, and suggests utilizing nail clippings as an initial diagnostic tool. The overall message is to enhance awareness and improve detection of serious nail conditions through careful observation and differential diagnosis.