Differential Diagnosis for Facial Swelling in a 78-Year-Old

Single Most Likely Diagnosis

• Benign Parotid Gland Neoplasm (e.g., Pleomorphic Adenoma): Given the description of a small cystic nodularity within the anterior superficial lobe of the right parotid gland, a benign neoplasm such as a pleomorphic adenoma is a common and likely diagnosis. These tumors are the most common type of salivary gland tumor and often present as a slow-growing, painless mass.

Other Likely Diagnoses

• Suppurative or Necrotic Intraparotid Lymph Node: As mentioned, the cystic appearance could also represent a suppurative or necrotic intraparotid lymph node, which could be related to an infectious process, although the absence of localized inflammation or abscess alongside the periodontal disease makes this less likely.
• Parotid Gland Cyst: A simple cyst of the parotid gland could also present with similar imaging findings and should be considered in the differential diagnosis.
• Periodontal Abscess or Infection: Although the CT does not show localized inflammation or abscess alongside the periodontal disease, it's possible that the facial swelling is related to an infection or abscess in the dental region that has not been fully captured by the imaging.

Do Not Miss Diagnoses

• Malignant Parotid Gland Tumor (e.g., Mucoepidermoid Carcinoma, Adenoid Cystic Carcinoma): Although less common than benign tumors, malignant tumors of the parotid gland must be considered due to their potential for significant morbidity and mortality if not diagnosed and treated promptly.
• Metastatic Disease to the Parotid Gland or Lymph Nodes: Metastases to the parotid gland or intraparotid lymph nodes from other primary sites (e.g., skin, lung, breast) are rare but critical to identify due to their implications for staging and treatment of the underlying cancer.

Rare Diagnoses

• Warthin's Tumor: A benign tumor of the salivary gland that is less common than pleomorphic adenoma but could present with similar imaging characteristics.
• Sjögren's Syndrome with Parotid Involvement: An autoimmune disorder that can cause salivary gland enlargement and could potentially present with cystic changes on imaging, although this would typically be bilateral and associated with other systemic symptoms.
• Kimura Disease: A rare, chronic inflammatory disorder that can involve the salivary glands and lymph nodes, typically presenting with lymphadenopathy and eosinophilia.