[1873] An Investigation into False Negative Transthoracic Fine Needle Aspiration/Biopsy Specimens

DM Minot, EA Jaben, MC Aubry, JS Voss, SG Van Epps, DJ Tuve, MR Henry, DR Salomao, PUY Lee, SK Carlson, AC Clayton. Mayo Clinic, Rochester, MN

Background: Transthoracic fine needle aspiration under CT-guidance (FNA) has proven to be a useful technique in the assessment of pulmonary nodules. We sought to determine the false negative (FN) rate at our institution and identify potential causes of our FN diagnoses.
Design: Medical records were reviewed from 1,043 consecutive patients who underwent CT-guided FNA/biopsy of lung nodules for a five-year time period (2002-2007). False negative cases, “negative” FNA/biopsy with malignant outcome, were identified. All cases were coded by the worst diagnosis from FNA or corresponding biopsy. Outcome was based on clinical and/or histopathologic evidence of disease. All cases were reviewed independently (blinded to original diagnosis) by three pathologists with 15 age and gender matched positive controls (PC) and negative controls (NC). Diagnosis (nondiagnostic, negative or positive for malignancy, atypical or suspicious) and qualitative assessments were recorded.
Results: There were 37 patients with a FN diagnosis (3.5%). Of the 36 cases available for review, 35 had core biopsy. Consensus diagnosis was suspicious or positive in 31% (11/36) of FNA cases (Table 1) and suspicious in 3% (1/35) of biopsy cases (Table 2), indicating potential diagnostic errors. Of the 12 diagnostic error cases, 9 were adenocarcinomas (5 primary, 4 metastatic), 1 squamous cell carcinoma, 1 metastatic renal cell carcinoma and one lymphoma. FN cases were smaller in size radiographically and tended to abut the pleura, while pathologically, they tend to be markedly necrotic and air-dried specimens.

FNA Consensus Diagnosis of FN, PC and NC cases
FN FNAPC FNANC FNA
Nondiagnostic104
Negative for Malignancy1909
Atypical501
Suspicious for Malignancy821
Positive for Malignancy3130
Total361515




Core Biopsy Consensus Diagnosis of FN, PC and NC cases
FN BiopsyPC BiopsyNC Biopsy
Nondiagnostic000
Negative for Malignancy33214
Atypical110
Suspicious for Malignancy120
Positive for Malignancy090
Total351414



Conclusions: Our FN rate is low (3.5%). Sampling error appears to be the most common cause for pulmonary FN diagnoses in 69% (25/36) of FNA and 97% (34/35) of biopsy specimens. Diagnostic errors account for 31% and 3% of our FN FNA's and biopsies respectively and were mostly adenocarcinomas (9/12).
Category: Quality Assurance

Monday, March 22, 2010 1:00 PM

Poster Session II # 214, Monday Afternoon

 

Close Window