FNAB cytology of chordoma masquerading as adenocarcinoma: case report.

We report a lesion of the mobile spine in a 77-yr-old white male who presented with lower back pain, radiating bilaterally to the legs, with numbness on walking and standing. Magnetic resonance imaging showed a large mass within L3-L4 vertebral bodies; however, chordoma was not suspected or suggested. Fine-needle aspiration biopsy (FNAB) of the mass revealed mostly blood with isolated flat clusters of polygonal rounded epithelial-like cells in a myxoid background. Immunohistochemistry could not be performed on the FNAB specimen due to inadequate material for cell-block. A limited immunocytochemistry panel was performed on one cytology smear. The tumor cells were immunoreactive for cytokeratin. During primary and expert evaluation, these features were interpreted as metastatic adenocarcinoma. Prostate and thyroid were suggested as possible primary sites. An extensive clinical and radiological search did not reveal a primary lesion. Four years later, the patient underwent surgical decompression and stabilization of his lumbar spine to avoid a catastrophic collapse of spine with neurological deficit. Histomorphological features and immunohistochemical studies at this time confirmed the lesion as chordoma. This case highlights the significance of considering chordoma in the differential diagnosis of FNAB cytology of spinal column lesions suggestive of adenocarcinoma, especially when the clusters of low-grade epithelioid cells with vacuolated cytoplasm in a myxoid background do not show epithelial structures such as papillae, glands, or acini.