The patient, a 64-year-old man, complained of pain of the right chest. Lung cancer was suspected by X-ray examination and was confirmed by cytological study of the sputum (Class V, adenocarcinoma).
He was treated by Linac X-ray irradiation and with anti-cancer drugs, After 2-week hospitalization, he was pointed out pleural effusion in the right chest. A yellowish-brown exsudate was aspirated and with the first materials was revealed an adenocarcinoma with multinucleated giant cells measuring 15-60 μin diameter. With the second materials, it was difficult to differentiate multinucleated giant cells from giant cell carcinoma or malignant mesothelioma because of a large amount of giant and multinucleated neoplastic cells.
The tumor cells were PAS and alcian-blue positive.
Electron microscopically, the tumor cells were found to have mucus-forming vacuoles, intracytoplasmic microcysts and cytophagocytosis.
Autopsy revealed carcinoma of the upper lobe of the right lung with extensive metastasis to lymph nodes. The right pleura was markedly fibrosed and thickened with tumor cell infiltrations. Microscopic diagnosis was bronchial adenocarcinoma with mucin formation.
In this case, cancer cells were observed to become multinucleate and gigantic due to treatment, which made diagnosis difficult. Further, as the therapeutic effect differed between free cells and filling proliferating ones, this cytologically interesting problem and others were discussed.
