Aggressive Digital Papillary Adenocarcinoma Mimicking a Giant Cell Tumour - A Case Report and Review of the Literature.

Aggressive digital papillary adenocarcinoma (ADPAca) is a rare, underreported, and often misdiagnosed malignant tumour of the eccrine sweat gland, with high recurrence and metastatic potential. We present a case of a painless mass over the middle phalanx of the dominant index finger in a 51-year-old man. The mass was present for over 20 years, which had slowly increased in size. The patient only presented when it began to interfere with his profession as an electrician. The clinical presentation was consistent with a giant cell tumour. Histological diagnosis was of an ADPAca. Staging investigations were negative and he subsequently went on to have a ray amputation. The importance of high clinical suspicion of digit lesions is highlighted. No specific histologic features have been identified to predict recurrence or metastasis. We review the merits of performing sentinel node biopsy and alternative treatment options such as Moh's micrographic surgery. We review the international literature to assess metastatic potential and follow-up requirements.