Aggressive Digital Papillary Adenocarcinoma With Multiple Organ Metastases: A Case Report and Review of the Literature.

Aggressive digital papillary adenocarcinoma (ADPA) is a rare sweat gland neoplasm with a high recurrence rate and metastatic potential. In this study, the authors describe a case that originally appeared to benign spiradenoma, but took an ominous course eventually resulting in the diagnosis of ADPA. A 73-year-old woman developed a gradually growing nodule on the second toe of her left foot, which she had first noticed 4 years previously. An excisional biopsy was performed followed by histological examination. The authors initially considered the tumor to be a benign spiradenoma and did not perform reexcision. However, she experienced local recurrence 24 months later, and multiple pulmonary metastasis 31 months later. On histological examination, both the primary and locally recurrent tumors were found to be composed of discrete and well-circumscribed solid nodules, lacking cystic space. All tumors (the primary tumor, locally recurrent tumor, and lung metastases) presented with a pattern of fused back-to-back tubular structures and myoepithelial differentiation confirmed by immunohistochemical examination. On the basis of these findings, the authors finally diagnosed ADPA with multiple pulmonary metastases. The patient underwent chemotherapy, but died of disease 49 months later. This case highlights the importance of high clinical suspicion of ADPA when digital lesions present.