BACKGROUND: The aim of this study was to investigate the clinical significance of Quilty lesions in endomyocardial biopsies (EMBs) of cardiac transplantation patients. METHODS: A total of 1190 EMBs from 117 cardiac transplantation patients were evaluated histologically for Quilty lesions, acute cellular rejection, and antibody-mediated rejection. Cardiac allograft vasculopathy was diagnosed by computed tomography coronary angiography. Clinical information, including the patients’ survival was retrieved by a review of medical records. RESULTS: Eighty-eight patients (75.2%) were diagnosed with Quilty lesions, which were significantly associated with acute cellular rejection, but not with acute cellular rejection ≥ 2R or antibody-mediated rejection. In patient sdiagnosed with both Quilty lesions and acute cellular rejection, the time-to-onset of Quilty lesions from transplantation was longer than that of acute cellular rejections. We found a significant association between Quilty lesions and cardiac allograft vasculopathy. No significant relationship was found between Quilty lesions and the patients’ survival. CONCLUSIONS: Quilty lesion may be an indicator of previous acute cellular rejection rather than a predictor for future acute cellular rejection.
Allografts ; Biopsy ; Coronary Angiography ; Heart Transplantation ; Heart ; Humans ; Medical Records

Pathologic diagnosis of antibody-mediated rejection (ABMR) in ABO-incompatible (ABOi) transplantation patients is often challenging because patients without ABMR are frequently immunopositive for C4d. The aim of this study was to determine whether C4d positivity with microvascular inflammation (MVI), in the absence of any detectable donor-specific antibodies (DSAs) in ABOi patients, could be considered as ABMR. Methods: A retrospective study of 214 for-cause biopsies from 126 ABOi kidney transplantation patients was performed. Patients with MVI score of ≥2 and glomerulitis score of ≥1 (n = 62) were divided into three groups: the absolute ABMR group (DSA-positive, C4d-positive or C4d-negative; n = 36), the C4d-positive group (DSA-negative, C4d-positive; n = 22), and the C4d-negative group (DSA-negative, C4d-negative; n = 4). The Banff scores, estimated glomerular filtration rates (eGFRs), and graft failure rates were compared among groups. Results: C4d-positive biopsies showed higher glomerulitis, peritubular capillaritis, and MVI scores compared with C4d-negative specimens. The C4d-positive group did not show significant differences in eGFRs and graft survival compared with the absolute ABMR group. Conclusion: The results indicate that C4d positivity, MVI score of ≥2, and glomerulitis score of ≥1 in ABOi allograft biopsies may be categorized and treated as ABMR cases.