Pulmonary pathologic alterations associated with biopsy inserted hydrogel plugs

Radiologic and histopathologic features of hydrogel sealant after lung resection in participants of a prospective randomized clinical trial

PURPOSE

To summarize imaging and histopathologic characteristics of hydrogel sealant (plug) in lung parenchyma and assess their correlation with time since deployment of sealant.

MATERIALS AND METHODS

Among a total of 208 participants randomized to the hydrogel sealant arm of a lung biopsy prospective randomized clinical trial, 51 underwent resection of the biopsied lesion. In 34 participants sealant material was present on histopathologic sections (n = 22), or they had cross-sectional imaging of chest between biopsy and resection (n = 23) or they had both imaging and histopathology (n = 11). Histopathologic and imaging findings were described. The association of these findings with time since sealant deployment was evaluated using the Wilcoxon rank sum test.

RESULTS

The mean time since sealant deployment for histopathology was 45.7 days (median 36, range 14-181) and for imaging studies was 99 days (median 32, range 4-527). The sealant was infiltrated by inflammatory cells in 20 (91%) participants. The main general histopathologic pattern of sealant was foamy in 12 (57%) and mesh in 8 (38%) participants. Imaging appearance of sealant was serpiginous in 18 (60%), linear in 10 (33%) or lobulated in 2 (6.7%) participants. In 2 participants the sealant was hypermetabolic with no histopathologic evidence of tumor. No correlation was found between time since sealant deployment and imaging or histopathologic appearances.

CONCLUSION

Hydrogel sealant appears as a serpiginous, linear, or lobulated opacity on cross-sectional imaging which can be metabolically active. It is associated with an inflammatory reaction with a foamy or mesh general pattern on histopathological assessment. No correlation was found between time since sealant deployment and imaging or histopathologic appearances.

Impact of Histopathologic Changes Induced by Polyethylene Glycol Hydrogel Pleural Sealants Used During Transthoracic Biopsy on Lung Cancer Resection Specimen Staging

Patients undergoing transthoracic needle core lung biopsy (TTNB) are at risk for biopsy-related pneumothorax. Instilling pleural sealant at the pleural puncture site reduces this risk. The impact of histologic changes associated with pleural sealant on assessing the histologic type and pathologic stage in lung cancer resection specimens has not been previously evaluated. All lung cancer resection specimens from 2015 to 2018 in which polyethylene glycol hydrogel pleural sealant was instilled during TTNB were reviewed. Thirty-three cases were identified. TTNB preceded lobectomy by an average of 35 days. Amphophilic, weakly polarizable, crinkled pleural sealant material was associated with tumor in 11 cases (33%), including 8 adenocarcinomas, 2 squamous cell carcinomas, and 1 pleomorphic carcinoma that averaged 1.7 cm in greatest dimension. Surrounding the sealant material was a 0.25 to 1.0 cm in greatest dimension pseudocystic space with a thin granulomatous rim of macrophages and multinucleated giant cells that occupied on average 17% of the tumoral area. Pleural sealant could have impaired assessment of pathologic stage in 1 case by obscuring the visceral pleural elastic layer, but definitive visceral pleural invasion was present nearby. Although hydrogel pleural sealant instilled during TTNB has the potential to obscure important histologic features, in practice, it appears to have little or no adverse impact on the assessment of histologic type and pathologic stage in subsequent lung cancer resection specimens. Recognition of the histologic appearance of hydrogel pleural sealant and its associated tissue response is important for avoiding diagnostic misinterpretation.