A 52-year-old male presents with a non-healing ulcer on the lateral border of the tongue for 3 months. On examination, there is an indurated ulcer with rolled edges and surrounding erythema. The patient has a history of tobacco chewing. Which is the investigation of choice to confirm the diagnosis?

## Investigation of Choice for Oral Cavity Carcinoma **Key Point:** Incisional biopsy from the ulcer margin is the gold standard for confirming malignancy in oral cavity lesions with clinical suspicion of carcinoma. ### Why Incisional Biopsy? 1. **Histopathological confirmation** — provides tissue architecture, grade, and depth of invasion 2. **Adequate sampling** — taken from the junction of normal and abnormal tissue (ulcer margin) to capture both viable tumor and inflammatory zone 3. **Prognostic information** — allows assessment of differentiation (well/moderately/poorly differentiated) and staging 4. **Definitive diagnosis** — distinguishes carcinoma from benign ulcers (aphthous, traumatic, infectious) ### Clinical Correlation The clinical presentation—non-healing ulcer with indurated base, rolled edges, and history of tobacco use—is highly suspicious for squamous cell carcinoma (SCC) of the oral cavity. Once malignancy is suspected clinically, tissue diagnosis is mandatory before treatment planning. **High-Yield:** Incisional biopsy is preferred over excisional biopsy in oral cavity lesions because: - Excisional biopsy may compromise surgical margins if malignancy is confirmed - Incisional biopsy provides adequate tissue without interfering with definitive surgical planning ### Comparison of Investigation Modalities | Investigation | Sensitivity | Specificity | Use | |---|---|---|---| | Incisional biopsy | ~95% | ~99% | Gold standard; histology + staging | | Brush biopsy | 60–80% | 85–90% | Screening; non-invasive; low specificity | | FNAC | 70–80% | 90% | Lymph node assessment; not for primary lesion | | Toluidine blue | 70% | 60% | Adjunct for demarcation; not diagnostic | **Clinical Pearl:** Toluidine blue staining (vital staining) can highlight suspicious areas and guide biopsy site selection, but it is NOT diagnostic on its own and has poor specificity for malignancy. ### Biopsy Technique The biopsy should be: - Taken from the **ulcer margin** (junction of tumor and normal mucosa) - **Incisional** (not excisional) to preserve surgical anatomy - Adequate depth (includes submucosa) to assess invasion - Multiple sites if lesion is large [cite:Robbins 10e Ch 7]