Differential Diagnosis for Metastatic Papillary Thyroid Carcinoma in a Left Supraclavicular Firm to Hard Swelling

Single Most Likely Diagnosis

• Metastatic Papillary Thyroid Carcinoma: This is the most likely diagnosis given the clinical suspicion. Microscopic examination of FNA from a supraclavicular lymph node in a patient with a history of papillary thyroid carcinoma would likely show characteristic features such as overlapping nuclei, nuclear grooves, and intranuclear pseudoinclusions, which are diagnostic of papillary thyroid carcinoma.

Other Likely Diagnoses

• Metastatic Squamous Cell Carcinoma: This could be considered if the patient has a history of squamous cell carcinoma, especially of the head and neck region. The FNA would show features of squamous cell carcinoma such as keratinization and intercellular bridges.
• Metastatic Adenocarcinoma: If the patient has a history of other adenocarcinomas (e.g., breast, lung, gastrointestinal), the FNA could show features of adenocarcinoma, including gland formation and mucin production.
• Reactive Lymphoid Hyperplasia: Although less likely, reactive changes in lymph nodes can sometimes mimic malignancy. The FNA would show a polymorphic population of lymphocytes without atypia.

Do Not Miss Diagnoses

• Lymphoma: Both Hodgkin and non-Hodgkin lymphoma can present with supraclavicular lymphadenopathy. The FNA would show a monomorphic population of lymphocytes with atypia, and specific markers would be necessary for diagnosis.
• Melanoma: Metastatic melanoma can present with lymphadenopathy, and the FNA would show pigment and characteristic nuclear features such as large nuclei with prominent nucleoli.

Rare Diagnoses

• Medullary Thyroid Carcinoma: Although rare, medullary thyroid carcinoma can metastasize to lymph nodes and would show characteristic features such as spindle or plasmacytoid cells with amyloid deposition.
• Other Neuroendocrine Tumors: Rarely, other neuroendocrine tumors (e.g., carcinoid, neuroblastoma) can metastasize to supraclavicular lymph nodes and would show characteristic features such as small, round, blue cells with neuroendocrine markers.
• Sarcomas: Very rarely, sarcomas can metastasize to lymph nodes, and the FNA would show features of the specific sarcoma type, such as spindle cells in leiomyosarcoma or malignant cartilage in chondrosarcoma.