When A Patient Presents With An Unusual Lesion On The Sole
A 60-year-old Caucasian female patient presents for consultation to the foot and ankle clinic regarding a one-year history of an erythematous, scaly and irregular lesion on the sole of her right foot. She notes the lesion is entirely asymptomatic. She originally saw a primary care physician about the lesion. The physician told her that she had a case of “athlete’s feet” and recommended an over-the-counter (OTC) antifungal cream. After four weeks of treatment with the antifungal cream, the patient showed no improvement.
The primary care physician then re-diagnosed the lesion as “eczema” and prescribed an intermediate strength topical cortisone cream. However, after two weeks of treatment, the lesion again failed to respond. Since the lesion was not pruritic and did not hurt, the patient simply quit worrying about it. Yet she recently noticed that it appeared to get bigger so she sought a second opinion.
The patient has had no known exposures to any new drugs, chemicals, paints, toxins, irritants or other potential allergens. She is currently taking a thyroid supplement but denies taking any other medications, vitamins or supplements. Her husband recently died due to heart failure and no one else in her household or within her family has any similar conditions.
What The Exam Revealed
Examination of the plantar aspect of the patient’s right foot reveals an obvious lesion that demonstrates a slightly elevated, red, irregular, scaly plaque with surface fissures and some crusts along with well-defined borders on the non-weightbearing surface. The lesion does not involve other parts of the foot or ankle, and there is no involvement of the hands or nails. There are no targetoid lesions or other distinctive skin lesions. There is also no color or inflammatory changes involving the eyes or ears. There are no tongue or oral cavity lesions or discolorations present. The patient has normal vital signs and there is no elevation of the oral temperature. The remaining portion of the physical examination is within normal limits and the patient has no other clinically significant skin conditions.
A Closer Look At Bowen’s Disease
The most likely diagnosis is intraepidermal (in situ) squamous cell carcinoma (Bowen’s disease). Bowen first described this entity in 1912 and described two cases. This squamous cell carcinoma (in situ) is a slow growing and scaly skin patch with a potential for significant lateral spread. The lesion may range from a few millimeters to several centimeters in diameter. Bowen’s disease presents as a single lesion in two thirds of cases. The term “in situ” simply means that the malignant cells are confined to the epidermis. However, there is evidence that the affected cells may migrate deeper into the skin layers and subsequently become a more aggressive form of skin cancer if this goes untreated.
Both chronic sun damage and inorganic arsenic ingestion have been implicated as etiologic factors in the development of Bowen’s disease. Researchers have also documented the human papilloma virus (HPV), especially HPV 16, as a cause of Bowen’s disease. In cases related to chronic UV exposure, the lesions may appear on sun-exposed areas of the head, neck, upper and lower extremities.
When it comes to cases in which Bowen’s disease occurs on areas of the legs and the plantar aspect of the feet, which are protected from the sun, these cases may often be related to inorganic arsenic exposure. This chemical was formerly present in several medications, such as “bromide mixtures,” Fowler’s solution and Gay’s solution, which were used for the treatment of epilepsy, psoriasis and asthma respectively. Inorganic arsenic was also used in occupational agents such as environmental fungicides, pesticides and weed killers. It was also commonly found in well water on many farms throughout the United States.