A cutaneous wound subjected to continuous irritation has an increased potential for malignant degeneration. The types of trauma that may give rise to the initial injury are diverse and have been well documented. We report a case of one such lesion in a 65-year-old man who had a persistent right forearm wound for over three years. The wound arose from the site of venous cannula puncture. Malignant transformation occurred in a manner comparable to that seen in other chronic lesions (Marjolin's ulcer).