Abstract
Background: Metastasis to the bone in breast cancer patients is common, but metastasis specifically to the appendicular skeleton is rare. A limited number of cases in the literature describe metastatic breast cancer to the distal limbs, also known as acrometastasis. Acrometastasis in a patient with breast cancer should prompt evaluation for diffuse metastatic disease. Case Report: We describe the case of a patient with recurrent triple-negative metastatic breast cancer who presented with thumb pain and swelling. Radiograph of the hand demonstrated focal soft tissue swelling over the first distal phalanx with erosive changes to the bone. Palliative radiation to the thumb resulted in symptom improvement. However, the patient succumbed to widespread metastatic disease. At autopsy, the thumb lesion was confirmed as metastatic breast adenocarcinoma. Conclusion: Metastatic breast carcinoma to the distal appendicular skeleton, specifically to the first digit, is a rare presentation of bony metastasis and can be an indication of late, widespread disease.