Case ReviewsBenign Mesothelial Cell Proliferations May Mimic Neoplasms in Posttransplantation Surveillance Transbronchial Biopsies: Two Case Reports and Review of the LiteratureHuebner, Thomas MD*; Wei, Peter MD†; Staats, Paul N. MD*†; Burke, Allen MD*†Author Information From the *Department of Pathology, University of Maryland Medical Center, and †University of Maryland School of Medicine, Baltimore, MD. Reprints: Thomas Huebner, MD, University of Maryland Medical Center, Department of Pathology, 22 S. Greene St, NBW43, Baltimore, MD 21201. E-mail: [email protected]. The authors have no funding or conflicts to declare. Pathology Case Reviews: November/December 2012 - Volume 17 - Issue 6 - p 252-254 doi: 10.1097/PCR.0b013e3182759321 Buy Metrics Abstract Transbronchial biopsy is the current criterion standard for the diagnosis of allograft rejection in the lung. Rarely, benign proliferations of mesothelial cells may be present within the biopsy specimen, either as benign-appearing cellular aggregates or as neoplastic-appearing epithelioid structures. When present, these benign mesothelial proliferations may mimic common non–small cell neoplasms, leading to misdiagnosis and possible unnecessary testing or treatment of the patient. We present 2 new cases of benign mesothelial proliferations identified at the time of lung biopsy for allograft rejection and present a brief review of the literature related to this phenomenon. © 2012 Lippincott Williams & Wilkins, Inc.