A 52-year-old man presents with a 3-month history of a painless, slow-growing mass in the right parotid region. On examination, there is a firm, mobile, well-defined swelling anterior to the sternocleidomastoid muscle. The overlying skin is normal. Which investigation is most appropriate to confirm the diagnosis and guide surgical planning?

## Investigation of Choice for Parotid Tumors: Surgical Planning ### Why MRI with Contrast is the Answer Here **High-Yield:** The stem explicitly asks for the investigation "to confirm the diagnosis **and guide surgical planning**." While FNAC is the standard first-line investigation for cytological diagnosis of a parotid mass, **MRI with contrast** is the investigation of choice when the question specifically emphasizes surgical planning — because it provides information that FNAC simply cannot. **Key Point:** MRI with contrast excels at: - Determining tumor location within the gland (**superficial vs. deep lobe** — critical for deciding extent of parotidectomy) - Identifying **facial nerve** involvement, displacement, or perineural spread - Delineating tumor margins and relationship to the mandible and skull base - Detecting deep lobe extension or parapharyngeal space involvement - Assessing for regional lymphadenopathy and staging ### Sequential Role of Investigations in Clinical Practice In real-world practice, the workup of a parotid mass typically follows this sequence: | Step | Investigation | Purpose | |---|---|---| | **1st** | **FNAC** | Cytological diagnosis — benign vs. malignant; guides urgency | | **2nd** | **MRI with contrast** | Surgical planning — extent, depth, nerve involvement | | **3rd (if needed)** | CT | Bony erosion, calcification, lymph node calcification | | **4th (if needed)** | Core needle biopsy | When FNAC is inconclusive and tissue diagnosis is mandatory | **Clinical Pearl:** The stem asks for a single investigation that both "confirms diagnosis **and** guides surgical planning." FNAC alone cannot guide surgical planning (it provides no anatomical information). MRI alone can provide strong diagnostic clues (e.g., pleomorphic adenoma has characteristic MRI signal) **and** is indispensable for preoperative planning. Therefore, MRI with contrast best satisfies **both** criteria in the stem. (Reference: Scott-Brown's Otorhinolaryngology, Head and Neck Surgery, 8th ed.; Bailey & Love's Short Practice of Surgery, 27th ed.) **Key Point:** FNAC is the first-line investigation for cytological diagnosis in isolation, but when the question asks for an investigation that serves **both diagnostic and surgical planning purposes**, MRI with contrast is the correct answer. This distinction is critical for NEET PG/INI-CET examination purposes.