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Zonguldak Karaelmas Üniversitesi Tıp Fakültesi, Patoloji Anabilim Dalı, Zonguldak Merkel cell carcinoma is an uncommon tumor arising usually on the sun-exposed skin of elderly individuals. A 64-year-old male patient, who undergone total laryngectomy operation seven years ago because of squamous cell carcinoma of larynx and got postoperative radiotherapy applied to the hospital with a subcostal mass. Histopathologic examination of the mass revealed tumoral infiltration with cytokeratin-20 expression that forming sheets and solid nests in subcutaneous tissue. The diagnosis was Merkel cell carcinoma. A vegetative tumor located in left main bronchi was observed during synchronously performed bronchoscopy and multiple biopsies were taken. Histopathologic diagnosis was pulmonary small cell carcinoma displaying positive reaction with thyroid transcription factor- 1 without cytokeratin-20 expression. It's extremely rare to encounter Merkel cell carcinoma coexisting with pulmonary small cell carcinoma. The current case has special importance due to being an extremely rare encountered tumor besides confirming these markers' reliability in distinguishing Merkel cell carcinoma from pulmonary small cell carcinoma. Keywords : Cytokeratin-20; Merkel cell carcinoma; pulmonary small cell carcinoma; thyroid transcription factor-1