A Case Report with Hutchinson’s Sign: What Could It Be Other than Melanoma in situ?

Introduction: Many conditions, such as malnutrition, radiation exposure, drugs, trauma, and systemic and metabolic disorders, can lead to nail pigmentation. Many other dermatological and systemic conditions, mycologic and bacterial infections, and repetitive trauma can be associated with non-melanoma-related Hutchinson’s sign. Case Presentation: We report a 68-year-old woman with the complaint of darkening of her existing nail bands and development of a newly pigmented lesion on the edge of her left thumb after taking chemotherapy. Lateral longitudinal biopsy, including Hutchinson’s sign, was performed. Melanocytes in normal number and localization in the nail matrix on histopathological evaluation. The patient was diagnosed with frictional hypermelanosis. Conclusion: It is very important to exclude subungual melanoma and to find out the etiology of Hutchinson’s sign. Repetitive trauma can be a cause of non-melanoma Hutchinson’s sign.