Metastatic Renal Cell Carcinoma to the Calcaneus and Talus Presenting as Plantar Fasciitis: A Case Study and Review of the Literature.

Renal cell carcinoma (RCC) is known for its propensity for distant metastasis, including skeletal involvement; however, metastatic spread to the foot, particularly the calcaneus and talus, is exceptionally rare, with fewer than 15 cases documented in the literature. We report a 59-year-old woman with a history of RCC treated with partial nephrectomy 7 years earlier who presented with 6 months of progressive left foot pain initially attributed to plantar fasciitis. Over the course of 4 emergency department visits spanning approximately 1 month, her oncologic history was not incorporated into the differential diagnosis. Advanced imaging ultimately revealed a 6.2 cm × 6.0 cm × 5.2 cm enhancing soft tissue mass infiltrating both the calcaneus and talus. Histopathology confirmed metastatic clear cell RCC. Given the extent of osseous destruction precluding viable reconstruction, the patient underwent below-knee amputation. Staging identified a concurrent pulmonary lesion, and postoperative systemic immunotherapy was initiated, though interval imaging demonstrated disease progression. This case highlights the diagnostic pitfalls of atypical RCC metastasis and underscores that a prolonged disease-free interval following nephrectomy should not diminish clinical suspicion. Inclusion of metastatic disease in the differential for refractory foot pain in any patient with an oncologic history is essential to enable timely diagnosis and preserve limb-salvage options.Levels of Evidence:Level V: Case reportStudy Design:Diagnostic case study (Level V); structured single-case analysis with systematic review of the published literature.