Unusual Presentations of Eccrine Porocarcinomas

Eccrine porocarcinomas (EPCs) are rare tumours, albeit the most common malignant adnexal tumours of the skin. They can present with very heterogeneous clinical and dermoscopic features, rendering diagnosis limited to histopathological examination alone. We share 2 cases of EPCs, one of which arose in a patient with a prior diagnosis of cutaneous squamous cell carcinoma (SCC) and another whose EPC was likely a malignant transformation of an existing poroma. An occurrence of porocarcinoma after the diagnosis of SCC may suggest the possibility of unknown risk factors for both. Positivity to androgen, oestrogen, and epidermal growth factor receptors was seen in a proportion of porocarcinomas, and this may prompt further research on combination therapy between conventional treatment modalities with hormone receptor antagonists. Malignant change of a poroma may be a more common phenomenon than we would expect based on the current literature.