Abstract

Myrmecia wart is a type of verrucae associated with infection of HPV1. Histologically, it is characterized by an endophytic growth pattern with abundant eosinophilic keratohyalin granules and conspicuous intranuclear inclusions with clear spaces around pyknotic nuclei. There have been reports on squamous cell carcinoma arising in association with verruca vulgaris. However, squamous cell carcinoma arising from a myrmecia wart has not been reported in the literature. Here, we report an unusual presentation of myrmecia wart that underwent malignant transformation into a squamous cell carcinoma. A 37-year-old female with history of liver transplant in 2007 presented with a lesion on her left great toe. Shave biopsy shows areas of classic myrmecia wart in most part of the lesion. Focally, there is confluent proliferation of keratinocytes with loss of normal architecture and absence of eosinophilic coarse keratohyline granules. These cells show significant cytological atypia depicted by nuclear enlargement, hyperchromasia, and brisk mitosis including atypical forms. The lesion is largely transected at the base. Given the overall histologic findings, a diagnosis of at least squamous cell carcinoma in-situ arising in a background myrmecia wart is made. The patient underwent Mohs surgery. The final pathology confirmed the initial diagnosis. The patient also has multiple painful warts on her hand that are resistant to nonsurgical treatments. Verrucae generally has low malignant potential on sites other than anogenital, oral pharyngeal, and periungual. Given the patient’s background of immunosuppression, it indicates that the risk of malignancy is much higher in population with immunocompromise. Close follow-up is warranted.