Eccrine Porocarcinoma: A Case Report of a Rare and Aggressive Cutaneous Tumour.

Eccrine porocarcinoma (EPC) is an extremely rare, adnexal carcinoma that represents less than 0.01% of all cutaneous malignancies. An aggressive tumour with a high recurrence rate, it has a tendency to metastasise to regional lymph nodes. Once metastasis has occurred, mortality rate increases to 75%-80% and thus survival is dependent on adequate and timely resection of the lesion. EPCs are frequently missed as a differential diagnosis due to their rarity and non-specific appearance, which can lead to serious consequences for patients. Consequently, EPCs are an important diagnosis for clinicians to be aware of and consider when evaluating cutaneous lesions.  We present a case of EPC of the knee, which was initially misdiagnosed as a benign lesion on magnetic resonance imaging (MRI). We discuss the use of MRI in aiding assessment of EPCs.