## Investigation of Choice for Oral Cavity Carcinoma ### Clinical Context The patient presents with a classic presentation of oral squamous cell carcinoma: an indurated, non-healing ulcer with raised everted margins and granular base on the tongue, along with cervical lymphadenopathy. ### Why Incisional Biopsy is the Gold Standard **Key Point:** Incisional biopsy from the margin of the ulcer is the investigation of choice for suspected oral malignancy. It provides: - Definitive histopathological diagnosis - Grade and type of malignancy - Depth of invasion - Margin assessment **High-Yield:** The biopsy should be taken from the margin (transition zone between normal and abnormal tissue) rather than the center, as the center often contains necrotic debris and does not yield diagnostic material. ### Biopsy Technique in Oral Cavity Carcinoma | Aspect | Incisional Biopsy | Excisional Biopsy | |--------|-------------------|-------------------| | **Size of lesion** | >1 cm (as in this case) | <1 cm | | **Diagnostic yield** | High (margin tissue) | High | | **Tissue depth** | Adequate for grading | Adequate | | **When used** | Suspected malignancy | Small lesions, benign-appearing | **Clinical Pearl:** Never perform excisional biopsy for suspected oral malignancy >1 cm, as it may cause tumor spillage and incomplete assessment of margins. ### Role of Other Investigations **Imaging (CT/OPG):** Used AFTER histological confirmation for: - Staging (T, N, M assessment) - Extent of local invasion - Bone involvement - Metastatic workup **FNAC:** Less useful for primary oral lesions; better suited for lymph node assessment. **Toluidine blue + brush biopsy:** Screening tool for oral dysplasia; insufficient for diagnosis of established malignancy. [cite:Robbins 10e Ch 7] 
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