Man With a Red, Scaly Lesion on One Digit

Following his routine rosacea follow-up visit, this 58-year-old man incidentally asked about a lesion on his left third digit. He pointed out a dime-sized, red, scaly patch on the dorsal aspect of the distal portion of the knuckle that extended toward the end of the finger (Figure). He denied itching, burning, stinging, or pain, and indicated that he did not habitually rub, pick, or scratch at the lesion.

Physical examination disclosed no similar lesions on either hand; no epitrochlear or axillary adenopathy was detected. The genitalia were free of lesions, and there was no history of genital warts.

Past medical history did include a somewhat distant occurrence of a basal cell carcinoma on the arm and several more recent actinic keratoses on the balding scalp.

"WHAT'S YOUR DIAGNOSIS?"

Answer on the next page

Diagnosis: Bowen Disease

The differential diagnosis consisted of psoriasis, wart, eczema, squamous cell carcinoma in situ (Bowen disease), and prurigo nodularis. The lack of any additional lesions suggested that psoriasis and eczema were not likely diagnoses. The patient denied traumatizing the area, which reduced the likelihood of prurigo nodularis (picker’s nodule). Thus, verruca (particularly a large flat wart) and Bowen disease remained as the major entities in the differential diagnosis.

A punch biopsy verified the diagnosis of squamous cell carcinoma in situ. Interestingly, in contrast with other non-melanoma skin cancers, Bowen disease of the fingers is often associated with the presence of mucosal-type, high-risk human papillomavirus.^1,2

The risk that extragenital Bowen disease will progress to invasive squamous cell carcinoma is estimated to be only 3%. Nonetheless, this lesion should be eradicated to avoid malignant transformation.³ There are a large number of treatment options, including surgical excision, electrodesiccation and curettage, carbon dioxide laser ablation, liquid nitrogen cryosurgery, topical photodynamic therapy, and topical application of either 5% 5-fluorouracil or 5% imiquimod cream.

The problem with this particular anatomical location is to choose an intervention that is least likely to lead to scarring and contraction, because the latter may interfere with functionality at the proximal interphalangeal joint. Application of topical 5% imiquimod was chosen; a large retrospective study had previously demonstrated a nearly 90% cure rate for Bowen disease with this topical immune response modifier.⁴ In addition, the treating physician had favorable experience managing digital Bowen disease with off-label use of 5% imiquimod in a combination regimen.⁵

As is typical of cutaneous squamous cell carcinoma in situ, daily application was done for 12 weeks, at which time moderate erosion had occurred over the entire lesion. Despite the induced erosion, the patient did not report notable pain or discomfort. Treatment was discontinued, and bland ointment was them applied 3 or 4 times daily to maintain a moist environment. Healing was complete in 3 weeks, without scar formation. There has been no recurrence in 4 years of follow-up.

References:

References1. Sato T, Morimoto A, Ishida Y, et al. Human papillomavirus associated with Bowen's disease of the finger. J Dermatol. 2004;31:927-930.
2. Nakajima H, Teraishi M, Tarutani M, et al. High prevalence of coinfection with mucosal high-risk type HPV (HR-HPV) and cutaneous HR-HPV in Bowen’s disease in the fingers. J Dermatol Sci. 2010;60:50-52.
3. Arlette JP, Trotter MJ. Squamous cell carcinoma in-situ of the skin: history, presentation, biology, and treatment. Australas J Dermatol. 2004;45:1-11.
4. Rosen T, Harting M, Gibson G. Treatment of Bowen’s disease with topical 5% imiquimod cream: retrospective study. Dermatol Surg. 2007;33:427-431.
5. Modi G, Jacobs AA, Orengo IF, et al. Combination therapy with imiquimod, 5-fluorouracil, and tazarotene in the treatment of extensive radiation-induced Bowen’s disease of the hands. Dermatol Surg. 2010;36:694-700.