Pulmonary spindle cell carcinoid. Needle aspiration biopsy, histologic and immunohistochemical findings.

Six pulmonary spindle cell carcinoids were reviewed. The patients were asymptomatic women ranging from 56 to 76 years of age. Four cases were diagnosed or suspected by percutaneous needle aspiration biopsy. The four patients treated by wedge resection or lobectomy showed no recurrence during the followup period; one patient was followed radiologically without resection for over five years, during which time the lesion remained stable. The cytologic preparations showed groups and single oval or elongated cells that had nuclei with finely granular, evenly dispersed chromatin, usually one small nucleolus and easily disrupted, finely granular cytoplasm. The histologic sections showed circumscribed or infiltrative neoplasms growing as sheets or vaguely organoid cell masses with vascular, focally hyalinized stroma. Immunoreactivity for chromogranin, neuron-specific enolase, synaptophysin, S-100 protein and Leu-7 was typically present; bombesin, serotonin, insulin and calcitonin were focally present in some cases. No reactivity for adrenocorticotropic hormone, somatostatin, gastrin, vasoactive intestinal polypeptide, pancreatic polypeptide, low-molecular-weight cytokeratin (MAK-6) or carcinoembryonic antigen was observed.