Diagnosis: Rodent ulcer

The lesion was a rodent ulcer. Often considered a synonym for basal cell carcinoma (BCC), “rodent ulcer” describes a skin cancer that has significantly invaded dermal tissues. The term underscores the capability of BCC to produce extensive local tissue destruction including cartilage and bone.

BCC is a malignant, cutaneous epithelial tumor derived from alterations in basal cells from the Malpighian layer of the epidermis. Tumors are slow-growing, frequently taking 10 years to reach the size seen in our patient. BCC occurs predominantly after the age of 60, but the lesions can appear in the third decade in patients with moderate-to-severe actinic skin damage.

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Although BCC occurs on any skin surface, the most common sites are the head and neck, followed by the shoulders and upper trunk. BCC does not occur on the mucous membranes except by adjacent invasion. The tumors normally occur de novo on the face, but they can follow trauma, such as burns; x-rays; and vaccinations. Nevoid lesions in which BCC can occur include nevus sebaceum and epidermal nevus. Genetic syndromes associated with basal cells include xeroderma pigmentosa, basal cell nevus syndrome, and Bazex syndrome. While there is a relationship with chronic UV exposure, the most important contributing factor is likely an inability to immunologically patrol and destroy aberrant epidermal cells.

BCC is the most common skin cancer found in people of Caucasian descent. Epidemiologic studies in North America note that the incidence of these tumors is increasing and they are being diagnosed in younger patients.

BCC is recognizable as a translucent (pearly) papule or nodule with telangiectasias and possibly central ulceration. Left untreated, lesions will continue to expand peripherally while the center remains ulcerative or sclerotic with an elevated, telangiectatic border. Neglected lesions can be extremely destructive and disfiguring. Metastasis is rare, with fewer than 150 cases reported. (In 30 years, I have not seen one BCC metastasize, although I have seen one invade the bone of the cranium.)

A superficial variety of BCC appears as an erythematous, slightly scaling, well-demarcated patch with a threadlike pearly border. Rarely, a morphealike form of BCC presents as a yellow-white, indurated plaque with ill-defined borders, resembling scleroderma. Occasional pigmentation in a BCC can obscure the lesion’s features, causing clinical confusion with other entities, such as seborrheic keratosis and melanoma.

The striking feature of the rodent ulcer is a hard rolled edge of cartilaginous consistency and pearly white color. The lesion has a tendency to improve and to appear to heal with or without scarring, giving rise to false hopes that may last for years.

Classic nodular BCC presents little clinical diagnostic difficulty, but many lesions are only suggestive of cutaneous malignancy and biopsy is needed for an accurate diagnosis. Consequently, the differential diagnosis of BCC includes dermatofibroma, nonpigmented nevus, seborrheic keratosis, pyogenic granuloma, sebaceous hyperplasia, squamous cell carcinoma, lupus erythematosus, Bowen’s disease, trichoepithelioma, cylindroma, eccrine acrospiroma, and some sweat-gland carcinomas.

The most common treatment approaches are surgical excision and electrodesiccation and curettage. Cure rates average well above 90% in most studies. Mohs surgery, which involves chemical in vivo fixation of cutaneous tissue, followed by serial excision and microscopic control, offers a high cure rate. At a cost of about $6,000 per lesion, Mohs surgery is usually reserved for difficult tumors, e.g., recurrent lesions in the nasolabial fold or the periorbital or periauricular regions.

Radiation is also effective, especially for lesions with ill-defined margins or in difficult locations and for patients who should avoid surgery. Some success has been reported with topical imiquimod and topical 5-fluorouracil.

Our patient’s tumor needed extensive surgical excision and reconstructive surgery. I had a member of my staff make the appointment with a plastic surgeon and follow up with phone calls to ensure that the surgery was undertaken.

Dr. Burkhart is clinical professor of dermatology at the University of Toledo College of Medicine in Ohio and clinical assistant professor of dermatology at Ohio University College of Osteopathic Medicine, in Athens.