Intraoperative cytologic diagnosis of symptomatic carcinoma (pulmonary small cell carcinoma) metastatic to the pituitary gland: a case report.

BACKGROUND: Carcinoma metastatic to the pituitary gland is infrequent and has been reportedly detected in approximately 1% of pituitary surgical cases. It may masquerade as a pituitary adenoma both clinically and radiologically. CASE: A 49-year-old man presented with a 1-month history of severe headache, diplopia and blurred vision. Neurologic examination revealed bitemporal hemianopsia and left sixth nerve palsy. The initial radiologic diagnosis based on magnetic resonance imaging was pituitary adenoma. A biopsy of the lesion was performed. While intraoperative frozen section examination could not completely exclude an "atypical" pituitary adenoma, cytologic touch imprint findings were diagnostic of metastatic small cell carcinoma. Subsequently, additional workup revealed that the patient had a mass lesion in the right lung and right-sided mediastinal lymphadenopathy on chest computed tomography. This was a rare case of pituitary metastasis as the first manifestation of an occult malignancy. CONCLUSION: For intraoperative diagnosis at the time ofpituitary surgery, cytologic imprints can be used reliably to make a diagnosis not only of pituitary adenoma but also of metastatic lesions. It is appropriate in current neuropathology practice that the imprint method be used as the sole modality for intraoperative consultation for pituitary lesions.