ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 DSA. All patients who developed a de novo DSA were offered a biopsy. We report here histological findings in these biopsies using the Banff classification. Results: Out of 570 consecutive transplant patients, 82 develop DSA at mean 42 days (+/- 106 days) post-transplant (14.4%)( 39% Class I, 40% class II, 21% class I + class II). 57/82 patients had a biopsy at a median of 33 days (+/- 114) post-DSA detection. 47% did not show any histological features of rejection, 30% showed histological features of AMR (either suspicious for or definite AMR), 16% showed only histological features of T cell-mediated rejection (TCMR) (either borderline and TCMR) and 7% had his- tological features of both AMR and TCMR. Conclusion: In a prospective cohort of patients with de novo DSA, 53% of those investigated with a biopsy showed histological features of rejection (including incomplete/suspicious features). Next steps will involve molecular analysis of those biopsies. E-PS-16-004 The importance of renal biopsy in haematological neoplasms. A particular diagnosis I. Sánchez Ramírez*, F. Leiva-Cepas, J. Osuna Soto, M.J. Gálvez Medina, A. González-Menchén *Hospital Universitario Reina Sofía, Spain Background & objectives: Angioinmunoblastic T-cell lymphoma (AITL) is a rare form of peripheral T-cell lymphoma , wich can have renal involvement. The aim of this case is to emphasize the importance of renal biopsy for diagnosis of hematologic systemic diseases with renal manifestations. Methods: We report a man (48 yo) with diffuse lymphadenopathy and B symptoms, proteinuria (9g/24h), hypoalbuminemia (2,2 g/ dl) and hyperlipidemia (LDLc 134 mg/dl) - Nephrotic Syndrome, NS-. Other findings were kappa light chain elevation, high kappa/ lambda ratio, elevation of IgG, and eosinophilia. The histological study included renal, axilar adenopathy and bone marrow biopsy. Results: The biopsy of an axilar adenopathy showed a monomor- phic infiltrate of lymphoid cells, positive for Epstein-Barr virus (EBV), yet not conclusive, and follicular dendritic cell hyperpla- sia. The renal biopsy showed monomorphic proliferation of highly pleomorphic atypical T-cells (CD3+), with PD1 expression, and with polytypic plasma cells. The infiltrate affected the interstitium, without glomerular or tubular involvement. These cells were posi- tive for MUM1 (marker of activated T-cells and plasma cells). The cells infiltrating both lymph node and renal interstitium showed TCR rearrangement, yet these were a minor group in the lymph node compared to those found in the renal biopsy. The bone mar- row biopsy had not lymphoid cells infiltrate. Conclusion: AITL are aggressive and account for less than 1% of all lymphomas, and are associated to EBV in more than 80% of all cases. Several forms of renal involvement have been described, but they are very rare. Renal infiltration was described twice in the lit- erature, both associated with cutaneous rash and splenomegaly. NS due to renal infiltration only has been described once. Four cases of NS secondary to glomerulopathy associated with this entity have been described. E-PS-16-005 Renal biopsy findings following complement C5 inhibitor Ravulizumab treatment in a patient with C3 glomerulonephritis S. Turkevi-Nagy*, B. Iványi, Z. Prohászka, D. Jakab, C. Bereczki *University of Szeged, Albert Szent-Györgyi Health Centre, Department of Pathology, Szeged, Hungary Background & objectives: C3 glomerulonephritis is attributed to the dysregulated alternative complement pathway. The continuous C-activation can be blocked with monoclonal antibodies against C5. We present a patient’s renal biopsies with histologically and serologi- cally proven C3 GN before and after C5 inhibitor treatment. Methods: A 17-year-old, obese (BMI: 39,8kg/m2) Caucasian male patient was hospitalized for nephritic syndrome. Two years earlier, he had been diagnosed with C3 GN. Eculizumab treatment was effective, however, haematuria and proteinuria recurred after con- version to Ravulizumab. A renal biopsy was performed. Besides routine immunofluorescence, the slides were also evaluated for IgG subtypes. The findings were compared with previous pretreat- ment biopsies. Results: Active disease with diffuse-global endocapillary hypercellularity and membranoproliferative pattern was observed; 5% of the glomeruli exhibited fibrocellular crescents. Confluating deposits were seen along the capillary loops. Regarding IF, similarly to the pretreament biopsies, diffuse-global mesangial and peripheral C3 positivity was present. In addition, IgG2, IgG4 and restricted kappa deposition was seen in similar location as C3. EM demonstrated increased amount of mesangial, intramembranous and subendothelial deposits, which segmentally exhibited more dense, powdery-like appearance. There was a mild increase in Total Renal Chronicity Score (1/10 to 3/10). Complement serology tests found increased alternative pathway activity and consumption, confirming ineffective terminal complement blockade. Considering the obesity, the dosage of Ravulizumab was increased. Conclusion: We demonstrated a patient with novel IgG2-IgG4- kappa positivity in the same distribution as the deposited C3 fol- lowing Ravulizumab treatment. This immunophenotype and the powdery deposits on EM may correspond to the monoclonal anti- bodies binding to the terminal complement components. We imply that because of the increased body weight, the drug was possibly consumed by the accumulated complement. To our knowledge, this is the first documented case demonstrating the morphological effects of C5 inhibitor treatment in the European literature. E-PS-16-006 An atypical case of melanin deposition in kidney S. Sevim*, E. Isiktas Sayilar, I. Ergün, S. Kiremitci *Ankara University Medical School, Pathology Department, Turkey Background & objectives: Pigment deposition in kidney may result from various conditions most commonly due to rhabdomyolysis, intra- vascular hemolysis and cholestasis. Melanin deposition in kidney is a rare condition that is encountered in course of diffuse cutaneous mela- nosis in metastatic malignant melanoma (MM). Methods: We report a 28-year-old female patient presented with headache and high blood pressure with no significant previous clinical history. Physical examination was normal. Laboratory tests revealed very high level of serum creatinine (9.8 mg/dL). Urine analysis showed neither proteinuria nor haematuria. Renal biopsy was performed to clarify whether the kidney injury is acute or chronic. Results: Kidney biopsy revealed 17 glomeruli, which of 3 was globally sclerotic and acute tubular injury with regenerative changes in a background of interstitial fibrosis, tubular atrophy. Tubular epithelium were filled with golden-brown granular pig- ment which was confirmed to be melanin by Masson-Fontana. There were no atypical/malignant cells in the tissue. The biopsy was reported as acute tubular injury with diffuse tubular melanin deposition in scarred kidney, and it was recommended to investi- gate the patient systemically for a potential MM focus. However, S311