Mistaken Diabetic Ulcers: A Case of Bilateral Foot Verrucous Carcinoma

Abstract

Verrucous carcinoma (VC) is a rare, low-grade, and well-differentiated variant of squamous cell carcinoma. These tumors are slow-growing and exophytic and have a negligible incidence of metastasis. Treatment is complete surgical resection, ideally by Mohs micrographic surgery, to ensure adequate clear margins. Cutaneous VC predominantly occurs on the plantar surface of the foot and rarely occurs in multiple sites. This case study describes the fourth reported occurrence of bilateral VC of the feet in a woman with chronic diabetic foot ulcers. The case provides further support for persistent wounds contributing to the development of this lesion and describes their role in the characteristic delay in diagnosis of VC.

Figure 1

Exophytic lesion at the base of the first MTP joint of the right foot within a chronic diabetic ulcer. Pathology confirmed this lesion to be verrucous carcinoma.

Figure 2

Painful exophytic lesion on the plantar surface of the left 5th MTP joint, which, after multiple biopsies, was confirmed by pathology to be verrucous carcinoma.

Figure 3

Representative medium power image of the verrucous carcinoma demonstrates prominent surface hyperkeratosis and marked epidermal acanthosis, with a combined exophytic and endophytic growth pattern. Cytologic atypia is only mild to moderate. Rather than the infiltrative pattern typically seen at the deep edge of conventional invasive squamous cell carcinoma, verrucous carcinoma demonstrates insidious pushing-type invasion by expansile and irregular rete pegs (4x, H&E stain).