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Bronchiolitis obliterans (BO) is a fibrotic lung disease involving the small conducting airways. BO may be classified by etiology and underlying disease or, more commonly, by histopathological pattern. The two major histopathological categories are (1) BO organizing pneumonia (BOOP) and proliferative bronchiolitis and (2) constrictive bronchiolitis. The former is often idiopathic in nature and may also be associated with connective tissue diseases and inhalation injury. Characteristic findings on chest imaging include alveolar infiltrates and ground glass opacities and pulmonary function tests (PFTs) usually reveal restrictive dysfunction. Constrictive bronchiolitis is associated with organ transplantation, infections, connective tissue diseases, inhalation injury, and drugs and may also have an idiopathic origin. The radiographic characteristic is a mosaic pattern on high-resolution computed tomography (HRCT) and PFTs most often reveal obstructive dysfunction. This article will attempt to review constrictive BO, including histopathology, clinical presentation, radiographic appearance, and physiological findings, for both idiopathic diseases, as well as specific clinical-associated entities.

STUDY OBJECTIVES: The incidence of posttransplant lymphoproliferative disorder (PTLD) has been reported to range from 6.4 to 20% in lung transplant (LT) recipients. Postulated contributing factors include Epstein-Barr virus (EBV) infection and the use of immunosuppression, particularly muromonab-CD3 (OKT3)(Orthoclone OKT-3; Ortho Biotech; Raritan, NJ). We sought to examine these PTLD risk factors in 109 LT recipients at our institution who survived > 1 month. DESIGN: Retrospective review of EBV serology of all LT recipients at our institution. Our standard transplant protocol includes OKT3 for induction and refractory rejection, as well as lifelong acyclovir for herpes prophylaxis. We do not perform EBV donor-recipient matching. SETTING: A university-based LT center. RESULTS: We found that 5 of 109 patients were serologically negative for EBV prior to lung transplantation, and all of these patients converted following lung transplantation. The mean time to conversion was 151 days (range, 11 to 365 days). One fatal case of PTLD was documented in an EBV seroconverter (one of five patients) 12 weeks status posttransplantation for lymphangioleiomyomatosis. One nonfatal extrathoracic PTLD was documented in a seropositive patient (1 of 104 patients) 33 months posttransplantation. CONCLUSIONS: We conclude the following: (1) PTLD in LT recipients may have a lower incidence (2 of 109 patients; 1.8%) than previously reported, despite an aggressive immunosuppressive regimen; and (2) the incidence of PTLD is higher in patients with primary EBV infection (20% vs 1%).