Transbronchial cryobiopsy using an ultrathin cryoprobe with a guide sheath for the diagnosis of pulmonary mucosa-associated lymphoid tissue lymphoma.

Pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma is difficult to diagnose and relatively rare. Tissue sampling through transbronchial biopsy is often inadequate, necessitating surgical lung biopsy. However, a recently developed technique, transbronchial lung cryobiopsy (TBLC), has shown promise for obtaining larger specimens. A 1.1 mm cryoprobe has recently become available, and its usefulness has been increasingly reported. Use of a conventional cryoprobe for TBLC in diagnosing pulmonary MALT lymphoma has been previously reported; however, there are no reports on the use of a 1.1 mm ultrathin cryoprobe and guide sheath (GS). We aimed to assess the effectiveness and safety of using a 1.1 mm ultrathin cryoprobe in combination with a GS for diagnosing pulmonary MALT lymphoma using a simpler and safer method. We retrospectively analyzed the findings for four patients showing characteristic computed tomography (CT) findings of MALT lymphoma, including peripheral pulmonary lesions, air bronchogram nodules, and bronchiectasis, at our hospital. Each patient underwent endobronchial ultrasound (EBUS) with a GS, followed by TBLC using a 1.1 mm cryoprobe. Morphological diagnosis, immunohistochemical examination, and molecular testing were performed on the biopsy specimens to establish the diagnosis. Complications during the procedure were also monitored. We obtained 8-16 biopsy specimens in all four cases using a cryoprobe. Histopathological analysis of two cases revealed the infiltration of small lymphocytes with numerous lymphoepithelial lesions, confirming MALT lymphoma. Immunohistochemical examination further demonstrated B-cell lymphocyte proliferation and light-chain restriction, confirming monoclonality and providing a definitive diagnosis. In the remaining two cases, histopathological evidence of pulmonary MALT lymphoma was lacking. However, molecular testing using polymerase chain reaction to analyze immunoglobulin gene rearrangements revealed B-cell clonality, which supported the diagnosis. Molecular testing proved particularly useful when histopathological diagnosis alone was inconclusive. No complications such as pneumothorax or hemorrhage occurred during the procedure. The combination of a GS and EBUS facilitated specimen collection at the same location as EBUS, with the GS providing compression hemostasis and eliminating the need for an additional hemostatic device. Therefore, TBLC with a GS is a useful and safe method for diagnosing pulmonary MALT lymphomas and reproducibly yielded sufficient quantities of good-quality biopsy specimens.