Moderately differentiated neuroendocrine carcinoma (atypical carcinoid) of the supraglottic larynx. A report of two cases including immunohistochemistry and aspiration cytology.

Moderately differentiated neuroendocrine carcinoma of the larynx is morphologically distinct from the classic carcinoid and small-cell carcinoma. It is composed of medium to large polyhedral cells with an insular, trabecular, or acinar growth pattern, variable pleomorphism, and a tendency to metastasize to skin and bone. We describe the clinicopathological features of the tumor in two patients in whom tumor dissemination resulted in death 13 and 33 months after diagnosis. Both tumors occurred above the glottis and metastasized to bone but not to regional tissues. In one case, the diagnosis was confirmed when the aspiration cytological specimen from a rib lesion suggested a neuroendocrine carcinoma resembling medullary thyroid cancer (triangular cytoplasm, double nuclei, and fine red cytoplasmic granules on May-Grünwald-Giemsa staining). Both tumors were originally misdiagnosed as squamous cell carcinoma, as acinic cell cancer, or as suggesting metastasis of melanoma. Immunohistochemistry gave strong reactivity in both for chromogranin A and calcitonin, although the serum level of calcitonin, determined in one case, was normal.