Second malignant tumors detected by needle aspiration cytology.

Between 1967-1980, 14 second primary cancers were detected by needle aspiration cytology in patients treated for malignant tumors. The interval between the first cancer and the occurrence of the second cancer varied from six months to 21 years. In all 14 cases, the cytologic diagnosis of the second cancer was later confirmed by histopathologic examinations. In 13 patients, the second cancer was dissimilar from the first one, and in one patient the two cancers were subtypes of lymphoproliferative tumors. In three patients the cytologic diagnosis falsely defined the subtype of the second cancer. Malignant lymphoma was the predominant tumor either as the first cancer (50%) or as the second cancer (43%). Thyroid cancer occurred as the second cancer in three patients. Needle aspiration cytology of all newly appearing lesions can be performed routinely during follow-up examinations to discriminate between relapsed disease and new malignant tumors.