Lung cancer occasionally accompanies pulmonary hypertrophic osteoarthropathy (PHO) as a paraneoplastic syndrome. Here, we present an atypical case of pleomorhic carcinoma with PHO. A 59-year-old man with cough and arthralgia in both ankles was referred to our hospital and we made a diagnosis of PHO based on the typical findings in bone scintigram. Chest CT showed a 7 cm tumor in the right lung which was cytologically diagnosed as non-small cell cancer (cT2N2M0, stage IIIA). After resection of the tumor, his arthralgia and abnormal uptakes on bone scintigram disappeared. The final pathological diagnosis of the tumor was pleomorphic carcinoma. During adjuvant chemotherapy (cisplatin plus vinorelbine), relapsed lesions in the right pleural space were found. However, no symptoms of PHO were reported by the patient. Following the change of the regimen to carboplatin plus paclitaxel, the relapsed tumor went into complete remission, and this patient has now survived for three years without recurrence.