Differential Diagnosis for Squamous Cell Carcinoma in Bilateral Upper Cervical Lymphadenopathy

Single Most Likely Diagnosis

• Nasopharynx: The nasopharynx is a common site for squamous cell carcinoma that can metastasize to the upper cervical lymph nodes, even in the absence of a visible primary lesion. The location of the lymphadenopathy and the type of cancer suggest a strong link to nasopharyngeal carcinoma.

Other Likely Diagnoses

• Tonsils: Tonsillar cancer, often presenting with squamous cell carcinoma, can metastasize to the cervical lymph nodes. Although less likely than nasopharyngeal carcinoma to present without a visible primary, it remains a plausible source.
• Lungs: Lung cancer, particularly squamous cell carcinoma, can metastasize to cervical lymph nodes, though it more commonly spreads to hilar or mediastinal nodes. However, in the absence of other symptoms or findings, it's less likely but still a consideration.
• Esophagus: Esophageal squamous cell carcinoma can also metastasize to cervical lymph nodes, but it typically presents with dysphagia or other esophageal symptoms before lymphadenopathy becomes prominent.

Do Not Miss Diagnoses

• Tongue (Oral Cavity): Although less likely to present without a visible primary lesion, oral cavity cancers (including those of the tongue) can metastasize to cervical lymph nodes. Missing a diagnosis of oral cavity cancer could lead to delayed treatment of a potentially curable disease.
• Other Head and Neck Cancers: Including cancers of the hypopharynx, larynx, or sinuses, which can also present with cervical lymphadenopathy. These are less common but critical not to miss due to their potential for aggressive behavior and impact on prognosis.

Rare Diagnoses

• Skin Cancers: Rarely, skin cancers (such as squamous cell carcinoma of the skin) can metastasize to cervical lymph nodes, but this would typically be from a known primary lesion.
• Thyroid Cancers: Although thyroid cancers are more commonly papillary or follicular, squamous cell carcinoma of the thyroid is a rare entity that could potentially present with cervical lymphadenopathy.
• Metastatic Squamous Cell Carcinoma from Distant Sites: Very rarely, squamous cell carcinomas from distant sites like the uterus, bladder, or anus could metastasize to cervical lymph nodes, but these would be exceptional cases.