Highlights • Marjolin’s ulcers are a rare form of malignancy that present at regions exposed to chronic inflammation. • They are classically encountered in lower extremities more commonly than in the upper extremities. • This disease should be suspected in every case of chronic ulcer, where histological studies of the lesion must be conducted. • Treatment options vary according to local and regional factors. • Early recognition and control of the disease allow for better control and relapse., Background Marjolin’s ulcers are a rare form of malignancy that present at regions exposed to chronic infection. They present with a clinical triad of nodularity, induration, and ulceration greater than 3 months. Case report We present herein, an extremely rare case of Marjolin’s ulcer of the forearm, secondary to osteomyelitis, resulting from a 30-year neglection of external fixator used to treat a war injury of the forearm. Discussion Marjolin’s ulcers are classically encountered in lower extremities at sites of burns, trauma or complicated wounds. In the upper extremity however, they are seldom mentioned in literature. The presence of risk factors raise the suspicion of the disease. Conclusion Marjolin’s ulcer is rare sequelae of chronic wound infection. Patients often present after a latency period with exacerbated pain, discharge, and exophytic mass. This disease should be suspected in every case of chronic ulcer, where histological studies of the lesion must be conducted to exclude or confirm the diagnosis.