Warning of cancer by the sensation of octopus tentacles in the mouth

To the Editor

Paraneoplastic syndromes are defined as clinical symptoms resulting from damage to organs or tissues that are remote from the site of a malignant neoplasm (Darnell and Posner, 2003). We report the case of a paraneoplastic syndrome with abnormal oral sensation.

In early January 2015, a 61-year-old man suddenly felt a sensation of octopus tentacles in his mouth. Although he could neither see nor touch the tentacles, he could feel soft tentacles on his tongue, inner cheeks and soft palate. He felt 4 to 6 tentacles coming out from his inner cheeks bilaterally. After this strange experience, his family physician happened to find a renal mass on 14 February. Computed tomography (CT) revealed a 50 mm × 45 mm mass in the right kidney with no abnormality of the brain. The patient’s mental state was normal except for the abnormal oral sensation. He had no prior history of psychiatric illness, abuse of alcohol or illegal drugs. On 26 March, a laparoscopic radical nephrectomy was performed. The histopathological diagnosis was clear cell renal cell carcinoma. On 10 April, the sensation of tentacles completely vanished.

On 10 May 2016, the sensation of octopus tentacles in his mouth returned. On 1 June, CT showed a 15 mm × 10 mm nodule in segment (S) 1 + 2 of the left lung. A thoracoscopic partial resection was performed on 8 July. On 20 July, the sensation of tentacles vanished. The histopathological findings showed that the lung tumor was a metastasis of the renal cell carcinoma. Serum examination of onconeural antibodies (Anti-Hu, Anti-Yo, Anti-Ri, Anti-Ma2, Anti-CV2 and Anti-amphiphysin) were shown to be negative.

The sensation of octopus tentacles in the mouth recurred in 10 November 2016. On 5 January 2017, CT showed a 50 mm × 30 mm nodule in S 1 + 2 of the left lung (lung metastases) with invasion of the left subclavian artery. A further surgery was not indicated and chemotherapy was initiated on 27 February. On 13 March, the sensation of tentacles vanished.

In this case, the sensation of octopus tentacles in the mouth occurred three times. Repeatedly, the sensation appeared prior to diagnosis of cancer and vanished after resection of the tumor or chemotherapy. Although many patients with paraneoplastic syndromes have antibodies, it may occur without antibodies (Darnell and Posner, 2003; Graus et al., 2004). Therefore, we diagnosed his abnormal oral sensation (oral cenesthopathy) as seronegative paraneoplastic syndrome. It may be possible that such abnormal oral sensations constituted a warning of impending cancer.