UNUSUAL FEATURES OF METASTATIC ATYPICAL CARCINOID OF THE LARYNX

This report describes a case of atypical carcinoid of the larynx with metastatic tumor to cervical lymph nodes showing features similar to p araganglioma. Immunohistochemically, both the primary and metastatic t umor were positive for epithelial membrane antigen, cytokeratin, neuro n-specific enolase, chromogranin, synaptophysin, calcitonin and carcin oembryonic antigen. The sustentacular cells in pseudo-cell ball (''Zel lballen'') formations were shown by a positive S-100 marker. Electron microscopic analysis revealed numerous neuroendocrine granules measuri ng 150-250 nm in diameter. Clinical features, histological appearance, histochemical, immunohistochemical and ultrastructural findings, as w ell as differential diagnosis are discussed.