When Suspicious Bilateral Lesions Occur On Prior Hallux Amputation Sites

Jay Bornstein, DPM, FACFAS, and Larissa McDonough, DPM

What The Literature Reveals About Verrucous Carcinoma

In 1925, Buschke and Löwenstein described a slowly progressing neoplasm invading the anogenital area. However, it was not until 1948 when Ackerman coined the term verrucous carcinoma to describe a similar growth within the oral cavity.1,2 Researchers have subsequently isolated the low-grade tumor to other stratified squamous locations in the plantar foot, scalp, trunk and extremities.3 The pedal presentation, which this case report focuses upon, is commonly known as epithelioma cuniculatum, cuniatum plantaris or carcinoma cuniculatum.4 The plantar foot presentation of verrucous carcinoma is named primarily due to its physical and microscopic findings.

   Verrucous carcinoma is a derivative of squamous cell carcinoma, the most common malignancy found in humans.3 Squamous cell carcinoma typically evolves from precursors of actinic keratosis or squamous cell carcinoma in situ affecting keratinocytes.3 Although it is connected to squamous cell carcinoma, it is hypothesized that the plantar verrucous carcinoma variants have links to verrucous vulgaris as well due to the detection of human papillomavirus (HPV) types 6, 11, 16, and 18 in specimens.3,5,6,7 Also, histologically epithelioma cuniculatum resembles keratoacanthomas, verrucous vulgaris and epitheliomas.5

   Comparably with squamous cell carcinoma, verrucous carcinoma presents with slowly progressive exophytic growths and endophytic crypts or “rabbit burrows.”8,9 Specifically, epithelioma cuniculatum is common among males over the age of 50 and individuals with mental disorders.6,10 Researchers have seen some variants over areas of trauma including burns and scars as Marjolin’s ulcerations.11,12 Other inflammatory and neoplastic reactions can preclude verrucous carcinoma. These include chronic ulcerations, dermatoses, nail bed trauma, venous stasis, pemphigoid, lichen planus and nevi transformations.11,13

   Most patients have previously tried and failed topical therapies, thinking that they are treating another pathology. Differential diagnoses include dermatofibromas, seborrheic keratoses, tophaceous gout, pyogenic granulomas, eccrine poromas and amelanotic melanomas. Histologically, differential diagnoses are commonly between keratoacanthoma and verrucous vulgaris.4,13,14

   If neglected and in the absence of aggressive intervention, epithelioma cuniculatum can become regionally invasive into deeper soft tissue and osseous structures. There is also a rare chance of metastasis. More frequently, superficial bacterial infections can erupt, causing drainage and malodor within affected areas.4,5,8 Researchers have shown that magnetic resonance imaging (MRI) is the overall preferred pre-operative examination to evaluate lesions of a cryptic and invasive nature but computed tomography (CT) is superior for evaluating cortical disruption.9,10

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