A 58-year-old male tobacco chewer from rural Maharashtra presents with a 4-month history of a non-healing ulcer on the left buccal mucosa. On examination, the ulcer is 2 cm × 1.5 cm with indurated, everted margins and a granular base. The floor of the mouth shows mild induration. There is palpable cervical lymphadenopathy (2 cm, firm, mobile) on the left side. Biopsy confirms squamous cell carcinoma. CT imaging shows no distant metastases. What is the TNM stage of this tumor?

## TNM Staging of Oral Cavity Carcinoma ### Tumor (T) Classification The lesion measures 2 cm × 1.5 cm, which places it in the **T2 category** (tumor >2 cm but ≤4 cm in greatest dimension) [cite:AJCC Cancer Staging Manual 8e]. ### Node (N) Classification The presence of a **single ipsilateral cervical lymph node measuring 2 cm** (firm, mobile) indicates **N1 disease** (metastasis in a single ipsilateral lymph node ≤3 cm in greatest dimension). ### Metastasis (M) Classification CT imaging shows **no distant metastases**, so **M0**. ### Overall Stage **T2N1M0 = Stage III** oral cavity carcinoma. **Key Point:** Oral cavity carcinoma staging is based on the TNM system. The presence of any regional lymph node involvement automatically upgrades the stage to at least Stage III, regardless of T stage. **Clinical Pearl:** Mobile lymph nodes (as described here) suggest N1–N2 disease and are generally resectable. Fixed nodes (N3) carry a worse prognosis and may require multimodal therapy. **High-Yield:** Remember the T-stage cutoffs for oral cavity: T1 (≤2 cm), T2 (>2–4 cm), T3 (>4 cm), T4a (cortical bone/adjacent structures), T4b (masticator space/skull base/carotid artery).