When a Heel Won’t Heal. An Important Differential to Consider

To The Editor:

A 43-year-old woman recently presented to our dermatology department with a warty lesion on the medial aspect of her left heel (Fig. 1). The lesion, which was assumed to be a viral wart, had been present for 11 years and had proven refractory to all treatment attempts. She had visited several different clinicians with this lesion including her general practitioner and podiatrist, and multiple treatment modalities had been tried.

Figure 1. Warty lesion on medial left heel.

Figure 1. Warty lesion on medial left heel.

The lesion was very hyperkeratotic with a filiform architecture and was causing significant pain and limiting mobility. She was otherwise well with no comorbidities.

A curettage biopsy was arranged but was unfortunately too shallow to provide adequate information so a further incisional biopsy was performed (Fig. 2). This revealed a well-differentiated invasive squamous cell carcinoma at the base of the lesion, in keeping with carcinoma cuniculatum.

Figure 2. Histology image from incisional biopsy.

Figure 2. Histology image from incisional biopsy.

Carcinoma cuniculatum, so named because of its resemblance to a rabbit warren in terms of morphology, is a rare variant of squamous cell carcinoma. Although these tumors rarely metastasize, they can be locally invasive. Excision is the treatment of choice, and the size and depth of the excision depends on the extent of the tumor, which is usually confirmed on magnetic resonance imaging (MRI). [1]

Our patient's MRI revealed only soft-tissue involvement and surgical excision was arranged.

Although a rare condition, clinical suspicion is vital for the identification of this tumor as diagnosis relies on biopsy from the base of the lesion. It is an important diagnosis to consider in any recalcitrant warts.