Cutaneous Squamous Cell Carcinoma with Hypercalcemia of Malignancy and Skeletal Metastasis: Perioperative Case Report of Above-Knee Amputation.

Malignancy-associated hypercalcemia (MAH) is one of the most frequent and life-threatening metabolic emergencies in oncology; however, it is rarely observed in cutaneous squamous cell carcinoma (cSCC). We report the perioperative management of a 48-year-old man with a left long-standing anterior knee scar complicated by recurrent ulceration. In August 2024, pathology confirmed well-differentiated cSCC; however, the patient was lost to follow-up. One year later, he presented with a progressive ulcer, fatigue, severe hypercalcemia, and renal impairment. Laboratory evaluation revealed suppressed parathyroid hormone (PTH) levels consistent with MAH. Computed tomography angiography showed extensive ulceration with bone destruction and vascular involvement, and FAPI-PET/CT confirmed local recurrence and skeletal metastases in the contralateral tibia. Preoperative optimization consisted of isotonic crystalloid resuscitation, calcitonin, antiresorptive therapy with intravenous bisphosphonates or denosumab, and short-course continuous renal replacement therapy as indicated, allowing the patient to meet the physiologic criteria required for anesthesia induction. An above-knee amputation was performed using staged vascular control with continuous hemodynamic monitoring, followed by intensive care unit admission for targeted calcium-lowering therapy and organ support. The postoperative course was notable for the absence of fatal arrhythmias or deep surgical infection. This case highlights that, in cSCC complicated by MAH, skeletal metastases, and chronic infection, adherence to explicit physiologic thresholds for anesthesia induction within a standardized perioperative pathway -- combined with advanced imaging for metabolic and anatomic stratification -- can create a safe operative window of time, mitigate acute risks, and improve the feasibility and safety of definitive oncologic surgery in a high-risk setting.