Spindled carcinoid: The spindle-celled variant gets special consideration because of its potential confusion with other tumors. Most spindled tumors are peripheral or subpleural. More frequent in women and at an older age than other carcinoid tumors (mean age 58), these tumors are usually incidental findings [1,2]. Their behavior appears to be the same as that of other carcinoid tumors . Tumor grows in sheets composed of intersecting bundles of spindled cells. Nuclei are elongate with thin nuclear membranes, finely stippled chromatin, and small, inconspicuous nucleoli. The nuclear/cytoplasmic ratio is normal, and cytoplasm is pink and granular.
These tumors can be distinguished from small cell carcinoma, leiomyoma, schwannoma, chemodectoma, localized fibrous tumor of the pleura, and metastatic tumor by their strong staining for chromogranin A or by demonstrating large numbers of neurosecretory granules by electron microscopy.
1. Fekete P, Cohen C, DeRose P. Pulmonary spindle cell carcinoid. Needle aspiration biopsy, histologic and immunohistochemical findings. Acta Cytol 1990; 34:50-56.
2. Ranchod M, Levine G. Spindle-cell carcinoid tumors of the lung. A clinicopathologic study of 35 cases. Am J Surg Pathol 1980; 4:315-331.
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