An elderly woman underwent a radical mastectomy with radiation to the axilla 20 years ago. For 25 years, she has had an open wound that has never healed. It is not a recurrence of breast cancer. It is most likely:

First described by Marjolin in 1828 and known as Marjolin's ulcers, malignant degeneration arising in a chronic wound is nearly always squamous cell carcinoma. These lesions are most commonly seen in burn scars but have been associated with osteomyelitis, radiation therapy, hidradenitis suppurativa, and diabetic ulcers.