Vigilant follow-up and further imaging may be necessary for patients who show high clinical suspicion of lung cancer, despite initial pathology indicating a less threatening diagnosis of organizing pneumonia.
Kim
"In our study, we found that organizing pneumonia can mask underlying malignancy in up to 10% of patients undergoing CT-guided lung biopsy," said Charissa Kim, MD, PhD, an integrated interventional and diagnostic radiology resident at Beth Israel Deaconess Medical Center (BIDMC)/Harvard, in Boston.
Dr. Kim's research interests center on radiology-pathology correlations, with particular emphasis on identifying discrepancies between imaging findings and pathology data. "Looking into our data sets, we noticed that approximately 7.5% of lung biopsies for suspected lung cancer came back as organizing pneumonia on histopathology," Dr. Kim said. "We wondered how many of these patients were eventually diagnosed with malignancy later on."
She and her team, including her mentor, Olga Brook, MD, section chief of abdominal imaging at BIDMC, sought to assess the accuracy of CT-guided lung biopsy in diagnosing organizing pneumonia and to identify radiologic features associated with cases where cancer is later confirmed. The researchers hoped to provide insights into the potential limitations of biopsy results.
Dr. Kim and her team performed a retrospective analysis in which they identified 1,314 consecutive patients who underwent CT-guided lung biopsy for suspected lung cancer or metastatic disease between February 2014 and April 2022 at a single tertiary referral hospital.
"A pulmonary pathologist confirmed the presence of organizing pneumonia in all biopsy samples with no evidence of malignancy," Dr. Kim said. "We conducted a review of patient medical records, looking at follow-up imaging studies and repeat biopsies to determine the clinical outcomes of these patients."
Distinguishing Cancer From Organizing Pneumonia
A group of radiologists independently reviewed chest CTs and/or PET/CTs that were performed prior to the biopsy to identify radiologic features. Descriptive statistics were used for data analysis.
Out of 1,314 patients, 98 (7.5%) had biopsy results showing organizing pneumonia. Among these patients, the average age was 55 years, the median lesion size was 2.5 cm and 43 (44%) were women.
In 22 cases with an initial biopsy result of organizing pneumonia, repeat tissue sampling was performed due to a high clinical suspicion for malignancy. Of these, 10 represented malignancies. Subsequent biopsies, conducted a median of 51 days after the first biopsy, revealed pulmonary metastases in half of cases and primary lung cancers in the remaining half.
"Surprisingly, no specific imaging features were found to be associated with organizing pneumonia that occurred simultaneously with malignancy," Dr. Kim said.
Though her work with this study has concluded, Dr. Kim said it would be interesting to have more imaging information incorporated into tumor banks given the thought-provoking—and sometimes unexpected—findings between radiologic and pathologic data.
Dr. Kim acknowledged that a larger cohort may have been able to identify specific imaging features. "In a way, that remains a limitation of our study, though we were systematic in our analysis of our patients," she said. "As such, clinicians should remain aware of the potential limitation in relying solely on initial biopsy results for certain cases."
Access the presentation, "Missed Cancer Diagnosis Rate in CT-Guided Core Lung Biopsies with a Histopathologic Finding of Organizing Pneumonia," (M7-SSCH04-02) on demand at Meeting.RSNA.org.
