When A Patient Presents With An Unusual Lesion On The Sole
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.
Studies have shown that up to 50 percent of arsenical cancers reported involve Bowen’s disease. There is typically a lag time of greater than 10 years (often several decades) between exposure and the development of Bowen’s disease. Patients may not recall any previous contact with inorganic arsenic compounds.
In general, Bowen’s disease is more common in women (80 to 85 percent). It has been reported that Bowen’s disease is more prevalent among Caucasian people over the age of 40. Most patients diagnosed with Bowen’s disease are over the age of 60 and about 75 percent of all patients have lesions on the lower leg. Other locations include perianal, palms and soles and subungual locations. Pigmented and verrucous forms have been reported and are frequently misdiagnosed.
In regard to Bowen’s disease, one would primarily diagnose this disease via clinical features and dermatohistological confirmation is generally necessary. A shave biopsy or punch biopsy that incorporates any follicular structures is helpful. It is common to perform these procedures in the office with a local anesthesia. It is best to obtain the pathological analyses from board-certified dermatopathologists as opposed to general pathologists. The prognosis of Bowen’s disease is generally favorable. Around 3 percent of reported cases advance to invasive squamous cell carcinoma and metastases are even more rare.
The differential diagnosis includes psoriasis, eczematous dermatitis, tinea pedis, actinic keratosis, superficial basal cell carcinoma and lichen simplex chronicus among other conditions.
A Guide To The Differential Diagnosis
Psoriasis. This chronic condition affects many different parts of the body, including the palms and soles, and the typical plaque formation may appear similar in clinical presentation to Bowen’s disease, especially on the lower legs. Careful examination of the entire body may be helpful in finding other typical lesions. This condition is difficult to treat effectively and one can diagnose it with a punch biopsy.
Eczematous dermatitis. Next to tinea pedis, this is the second most misdiagnosed condition. The word eczema is derived from the Greek term ekzein, meaning “to boil out.” This term aptly describes the swollen, wet, oozy, bubbly appearance of acute eczema. When pruritic skin has been rubbed and scratched for weeks, it lichenifies into the dry, thick, scaly plaques of chronic eczema. Chronic plantar nummular and other eczematous dermatoses may look very similar to Bowen’s disease, and a biopsy will differentiate these conditions.
Tinea pedis. This is the most common misdiagnosis when the lesion is on the foot but one can see this concurrently with Bowen’s disease. Since most cases of Bowen’s disease occur on the lower leg, one should not often see this diagnosis.