Case Presentation: A 64-year-old male with newly diagnosed adenocarcinoma of the lung 1 month ago presented to a podiatrist due to significant left second toe pain. He was clinically diagnosed with gout and treated with meloxicam. Three days later he returned to the podiatrist due to worsening symptoms and was diagnosed with paronychia and treated with clindamycin. His condition continued to deteriorate and prompted an emergency room visit at the hospital. On physical exam, his left second toe was erythematous, swollen and tender to palpation. There was a decreased range of motion in his left foot due to pain. Dorsalis pedis pulses were +2/4 bilaterally. White blood cell count, ESR, and CRP were mildly elevated. ANA, uric acid level and CMP were unremarkable. An x-ray of foot revealed bone destruction involving the left second distal phalanx. He underwent a disarticulation and partial amputation of middle phalanx with pathology that was consistent with metastatic adenocarcinoma of the lung. Subsequent MRI of the brain confirmed stage IV adenocarcinoma of the lung. He was treated with radiation and chemotherapy.
Discussion: This case illustrates a unique presentation of metastatic adenocarcinoma to the distal phalanx. While it is a rare phenomenon, suspicion for bony metastasis should be raised in any patient with relevant risk factors for malignancy or newly diagnosed carcinoma. It is interesting to note that using a PET scan to help properly stage this lung cancer case missed any evidence of a distant metastasis to the foot, since these scans are conducted from the skull to mid-thigh. Therefore, this case highlights the importance of conducting a thorough medical history in order to quickly identify signs and symptoms of metastatic disease that may appear similar to infection or an inflammatory process. The use of imaging modalities including X-rays should not be undermined in an outpatient setting. Quickly recognizing signs of metastatic disease is essential to maximize the quality of life with appropriate treatment, as well as for the overall staging, management, and outcome of oncologic diseases.
Conclusions: Metastases to the bone develop in 30% of all patients with cancer, with only 0.007%-0.3% exhibiting acrometastases. Acrometastases to the phalanges of the toe are among the rarest cases reported in the literature. They are uncommonly the first presenting symptoms of the metastatic disease and can be mistaken for a benign condition. This case illustrates a unique presentation of metastatic adenocarcinoma to the distal phalanx. While it is a rare phenomenon, suspicion for bony metastasis should be raised in any patient with relevant risk factors for malignancy or newly diagnosed carcinoma.