Head and neck squamous cell carcinoma with femoral metastasis: a case report and systematic review of current literature.

Head and neck squamous cell carcinoma (HNSCC) predominantly spreads locoregionally, while distant metastases are uncommon and typically involve the lungs, liver, or axial skeleton; femoral metastasis is exceptionally rare. This study reports a case of femoral shaft metastasis arising from tongue squamous cell carcinoma and presents a systematic review of the existing literature to characterise clinical features, management, and outcomes. A systematic search of PubMed, Scopus, ScienceDirect, the British Medical Journal, and Google Scholar was conducted in accordance with PRISMA guidelines, identifying English-language case reports describing histologically confirmed HNSCC with femoral metastasis. Five published cases were identified and, together with the present case, six cases were analysed. The mean age at diagnosis was 57 years, with a male predominance (66.7%). The tongue was the most common primary tumour site (66.7%), and smoking was the most frequently reported risk factor. Time to femoral metastasis ranged from six months to 19 years, with most cases demonstrating early recurrence and advanced disease with nodal involvement or additional distant metastases. Management following femoral involvement was predominantly palliative and included radiotherapy, chemoradiotherapy, and orthopaedic stabilisation for impending or pathological fracture. Overall prognosis was poor, reflecting aggressive tumour biology and limited treatment options once distant skeletal disease is established. Femoral metastasis from HNSCC represents an advanced and uncommon disease manifestation, and early recognition is essential to facilitate timely palliative intervention, prevent skeletal complications, and optimise quality of life. Further multicentre studies and pooled analyses are required to better define risk factors, metastatic pathways, and optimal management strategies.