A wound that fails to close within a typical timeframe, usually defined as four to six weeks, often signals an underlying complication that prevents normal tissue repair. While most non-healing sores are caused by issues like poor circulation, diabetes, or chronic pressure, a persistent ulcer may occasionally represent a more serious condition: skin cancer presenting as a chronic wound. This phenomenon, known as a malignant ulcer, requires a high index of suspicion because the symptoms often mimic common, benign skin conditions. Recognizing that a wound is fundamentally incapable of healing is the first step toward a diagnosis that can significantly impact the patient’s outcome.
The Biological Obstacles to Wound Closure
A cancerous lesion physically prevents the natural healing cascade by hijacking the body’s repair systems. The tumor microenvironment (TME) maintains a state of chronic, disorganized inflammation that stalls the progression from the initial inflammatory phase to the subsequent proliferative and remodeling phases of wound repair. Normal wound healing relies on a highly coordinated switch between these phases, but the TME locks the site in a sustained, aberrant proliferative state.
Cancer cells corrupt surrounding non-cancerous cells, such as fibroblasts, transforming them into cancer-associated fibroblasts (CAFs). These CAFs deposit a dysfunctional extracellular matrix, which provides a scaffold for tumor growth instead of forming the structured scar tissue needed for wound closure. Tumors also generate a dense network of abnormal blood vessels through pathological angiogenesis, stimulated by factors like Vascular Endothelial Growth Factor (VEGF). This process siphons off oxygen and nutrients for the tumor’s proliferation, diverting these resources away from normal tissue repair.
The resulting blood vessels are structurally leaky and disorganized, creating areas of low oxygen (hypoxia) within the wound that perpetuate the inflammatory cycle. Immune cells, such as macrophages, are also corrupted by the TME to switch to an immunosuppressive phenotype. These cells actively protect the cancer cells rather than clearing the infection and debris needed for healing. This cellular and molecular chaos ensures the wound remains open, as the tumor growth program overrides the body’s repair program.
Common Malignancies Presenting as Chronic Ulcers
The most frequent malignancy arising in a chronic, non-healing wound is Squamous Cell Carcinoma (SCC). This is particularly true for Marjolin’s ulcer, an aggressive form of SCC that develops in long-standing scars, such as those resulting from burns, chronic osteomyelitis, or venous ulcers. The malignant transformation typically occurs after a long latency period, often averaging 30 to 35 years after the initial injury. SCCs arising in this context are aggressive and carry a higher risk of metastasis than SCCs associated with sun exposure, with metastatic rates ranging from 18 to 38%.
Basal Cell Carcinoma (BCC), the most common form of skin cancer, may also present as a chronic ulcer, particularly the nodulo-ulcerative or morpheaform subtypes. These cancers can ulcerate as they grow, mimicking a benign sore. Malignant Melanoma, particularly the fast-growing nodular type, also has the potential to ulcerate and be mistaken for a non-healing sore.
The lower extremities, especially the gaiter area of the leg, are the most frequent site for malignant ulcers, likely due to the high prevalence of underlying chronic conditions like venous stasis ulcers. Less common malignancies, such as cutaneous T-cell lymphoma, Kaposi’s sarcoma, or metastasis from internal cancers, can also manifest as chronic, atypical ulcers. The possibility of malignancy should be considered regardless of location if a wound is refractory to standard treatment.
Visual Signs Indicating Malignancy
A visual inspection can reveal several characteristics that set a malignant ulcer apart from a typical benign chronic wound. One telling sign is the appearance of the border, which may be rolled, everted, or raised, especially with BCC. Unlike benign ulcers that often have gently sloping edges, a malignant lesion can feel firm or indurated when touched, indicating tumor growth extending into the deeper tissue.
The wound bed often lacks the healthy, pink, granular tissue that signals active healing. Instead, the tissue may appear pale, necrotic, or covered with excessive, disorganized, and friable granulation tissue that bleeds easily. Malignant ulcers frequently exhibit rapid growth or a noticeable change in color, shape, or size over a short period. Any persistent, foul-smelling discharge or ulceration that develops in a pre-existing scar, especially an old burn scar, should increase the level of suspicion.
The Importance of Biopsy and Treatment Modalities
The definitive way to determine if a non-healing wound is cancerous is through a tissue biopsy. Medical guidelines recommend performing a biopsy on any ulcer that fails to show signs of healing after four to twelve weeks of appropriate standard care. The procedure involves taking a small tissue sample, typically using a punch, shave, or deep incisional technique. The sample must include tissue from both the center and the firm, atypical edge of the lesion.
Multiple tissue samples from different areas of the ulcer are often necessary because the malignancy may not be uniformly distributed. Once cancer is confirmed, the primary treatment is surgical, aiming for complete tumor removal while preserving surrounding healthy tissue. Surgical options include wide local excision, which removes the tumor along with a margin of healthy tissue, or Mohs micrographic surgery, used for certain skin cancers to precisely map and remove the cancer layer by layer.
For extensive or advanced malignancies, particularly those that have invaded deep tissues like bone, more aggressive measures such as amputation may be required. Adjuvant therapies, including radiation therapy or chemotherapy, are sometimes employed following surgery, especially if the cancer is aggressive or has a high risk of local recurrence or metastasis. Early detection through a timely biopsy improves the prognosis and limits the need for disfiguring or extensive surgical procedures.