Cytologic diagnosis of a solitary brain metastasis from papillary carcinoma of the thyroid - A case report

BACKGROUND: Papillary carcinoma of the thyroid metastasizes to the brain in rare instances. In published series and case reports of metastatic papilla ry thyroid carcinoma, diagnosis of central nervous system (CNS) metastases has been determined by histologic methods. We present a case of papillary c arcinoma metastatic to brain diagnosed by cytologic methods. CASE: A 43-year-old female, initially diagnosed at age 12 with papillary ca rcinoma of the thyroid metastatic to regional lymph nodes and lung, present ed with head aches of increasing frequency and severity. A computed tomogra phy scan confirmed a 1-cm nodule in the right inferior frontal lobe of the brain. For clinical reasons, the patient was followed with serial imaging f or five years. At age 48 there was significant progression of the CNS disea se, and the patient underwent stereotactic biopsy with drainage of cyst flu id. Cytologic examination of the cyst fluid and immunocytochemical studies confirmed the typical features of papillary thyroid carcinoma, including pa pillary clusters of cells with finely granular chromatin, micronucleoli, nu clear grooves and an associated psammoma body. CONCLUSION: Neurocytology is a useful technique in the examination of cysti c lesions of the brain and may be the sole technique for determination of d iagnosis.