BACKGROUND: Carcinosarcoma (sarcomatoid carcinoma) is a rare tumor with a high predilection for the aerodigestive tract. Cytologic diagnosis of metastatic carcinosarcoma has been reported in very few cases.
CASE: An 84-year-old woman presented with a 2-cm-diameter, right cervical lymph node that was referred for fine needle aspiration cytology (FNAC). She had received radiotherapy for a palatal squamous cell carcinoma 2 years earlier. The FNAC smears had a sarcomatoid appearance. Repeat fine needle aspiration was performed, with cytologic and immunocytochemical staining. Careful consideration of the cytologic and immunophenotypic features led to an impression of carcinosarcoma. Histologic sections of the palatal biopsy that had been previously diagnosed as squamous cell carcinoma were reviewed, and a final diagnosis of carcinosarcoma was established.
CONCLUSION: Metastasis of rare lesions, such as carcinosarcoma may be confusing and difficult to diagnose on FNAC, especially when the cytologic sample shows a predominantly sarcomatoid component. The difficulty is compounded when the sarcomatoid component happens to have been overlooked on the initial histologic assessment. With representative cytologic sampling, immunocytochemical staining and review of the histologic material, the correct diagnosis was achieved in this case.