Transthoracic image-guided biopsy of lung nodules: when is benign really benign?

A pathologic diagnosis of malignancy by image-guided transthoracic fine needle aspiration (FNA) with or without (+/-) core biopsy is definitive. However, a benign diagnosis of a lung nodule by FNA +/- core biopsy presents a management dilemma of resection for confirmation versus follow-up imaging and/or medical treatment. We propose three separate pathologic categories of benign diagnosis after FNA +/- core biopsy: (i) benign specific (ie, aspergillosis); (ii) benign nonspecific (ie, fibrosis); and (iii) nondiagnostic. Our goal was to define when to resect "benign" nodules to avoid an unacceptably high false-negative rate.

All FNA +/- core biopsy diagnoses considered nonmalignant at a single institution from 1996 to 2001 were retrospectively reviewed for management and outcomes by radiologic or pathologic follow-up.

Ninety-five of 836 total cases with FNA +/- core biopsies over the 5-year period were identified as nonmalignant and had complete pathologic or radiologic follow-up. Twenty-one of 95 had a benign specific diagnosis; all were true-negative for malignancy on radiologic (n = 17) or surgical (n = 4) follow-up. The remaining 74 had either benign nonspecific (n = 53) or nondiagnostic (n = 21) diagnoses. Seven of 53 benign nonspecific specimens (13%) and six of 21 nondiagnostic specimens (29%) were malignant at excisional biopsy or radiologic follow-up. Sixteen of 95 (17%) had a postprocedural pneumothorax requiring a chest tube.

Transthoracic FNA +/- core biopsy may yield a nonmalignant diagnosis as (i) benign specific, (ii) benign nonspecific, or (iii) nondiagnostic. Diagnosis-directed medical management is recommended for a benign specific diagnosis. Additional diagnostic studies, repeat biopsy, or resection is necessary for benign nonspecific and nondiagnostic biopsy results as a result of an unacceptably high rate of malignancy.