When A Patient Presents With An Unusual Lesion On The Sole
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.
Actinic keratosis. This condition is more common on sun-exposed areas of the body and rarely occurs on the plantar aspect of the feet. However, this condition may be very similar to Bowen’s disease when it presents on the lower legs. The distinction between the two is a matter of degree (the extent of the lesion) as opposed to differences in individual cells. One will often see marked hyperkeratosis and areas of parakeratosis with loss of the granular layer. A dense inflammatory infiltrate is usually present. The case has been made that actinic keratosis is the earliest manifestation of squamous cell carcinoma and one should regard it as such rather than as a precancerous lesion. Biopsy of the lesion will help confirm the diagnosis.
Superficial basal cell carcinoma (BCC). This variety of BCC appears as scaly patches or papules that are pink to reddish-brown, and often have central clearing. A threadlike border is common. Erosion is less common in superficial BCC than in nodular BCC. Superficial BCC is common on the trunk and has little tendency to become invasive. The papules may mimic Bowen’s disease, psoriasis or eczema, but they are not prone to fluctuate in appearance. Numerous superficial BCCs may indicate arsenic exposure. Biopsy is essential in the diagnosis.