Efficacy of cryobiopsy during medical thoracoscopy for diagnosing malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is difficult to differentiate from other pleural diseases, and its diagnosis requires adequate tissue sampling. Although medical thoracoscopy is an established diagnostic procedure for pleural diseases, there is no consensus on whether it guarantees a high diagnostic yield for MPM. Cryobiopsy has been shown to have the potential to improve tissue sampling in other diseases; therefore, we aimed to investigate its efficacy in diagnosing MPM.

Patients who underwent medical thoracoscopy at our institution between January 2013 and June 2023 and were finally diagnosed with MPM were analyzed. Patients who underwent biopsies with forceps and/or electrocautery devices were defined as the conventional group, whereas those who underwent biopsies with an additional cryoprobe were categorized as the cryo group. Diagnostic performance was compared between the two groups.

Among 347 patients who underwent medical thoracoscopy, 69 patients, 34 in the cryo group and 35 in the conventional group, were diagnosed with MPM. The overall diagnostic yield was 76.8 %, and the cryo group had a significantly higher yield than the conventional group (88.2 % vs. 65.7 %, P = 0.044). Furthermore, the subtype was confirmed in most of the patients in the cryo group but only in approximately two-thirds of those in the conventional group (79.4 % vs. 42.9 %, P = 0.003). Regarding safety, two patients (5.9 %) developed pneumothorax in the cryo group, and two (5.7 %) developed pneumonia in the conventional group.

Cryobiopsy is effective in improving the subtype confirmation rate as well as MPM diagnostic yield compared to conventional biopsy.