ECP 2022 Abstract Book

Virchows Archiv (2022) 481 (Suppl 1):S1–S364 13 none of the clinical/radiological examinations revealed any mass lesion that could favour MM. It has been more than 2 years of fol- low up that the patient is still stable. Conclusion: According to literature review, relevant published reports presented melanin deposition in kidney as a manifestation of diffuse cutaneous melanosis. However our unique case shows that it is not always associated with MM. This finding makes it even more difficult to understand the physiopathogenesis of mela- nin deposition in tissues in the absence of concomitant tumour component. E-PS-16-007 An unusual case of diffuse lupus nephritis with features sugges- tive of overlapping cryoglobulinemic glomerulonephritis G. Terinte-Balcan*, G. Stefan, S. Stancu, S. Cinca, M. Gherghiceanu *"Victor Babes" National Institute of Pathology, Romania Background & objectives: Cryoglobulinemic vasculitis can be associ- ated with many diseases such as tumours, infections or autoimmune processes. Even though features of cryoglobulinemic vasculitis have been rarely described in patients with lupus, the exact link between the two diseases remains unclear. Methods: A 39-year-old female was admitted in our nephrology unit for nephrotic syndrome. Blood tests showed low C3 and C4 and positive ANA, anti-Ds-DNA, anti-SSA and SSB. Serum cryoglobulins were negative. A kidney biopsy was performed and the tissue was divided for light microscopy (LM), immunofluorescence microscopy (IF) and electron microscopy (EM). Results: LM showed 8 glomeruli with PAS+ hyaline thrombi in most capillary loops, marked thickening of capillary walls and mild segmental endocapillary hypercellularity. Rare glomeruli had segments of tuft sclerosis. IF showed “full house” staining. EM showed dense deposits that were in the mesangial areas, intramembranous, subendothelial and subepithelial. Some depos- its had a vague microtubular structure on high magnification. A diagnosis of diffuse lupus nephritis (class IV) with features sug- gestive of associated cryoglobulinemic glomerulonephritis was made. The patient was started on intravenous cyclophosphamide. After six months of induction therapy, remission of the nephrotic syndrome was obtained and maintenance therapy with azathio- prine was initiated. Conclusion: This case represents an unusual case of diffuse lupus nephritis. The massive intracapillary deposits (“hyaline thrombi”) and also the vague microtubular structure observed in some of the deposits using high magnification on EM raises the possibility of concurrent cryoglobulinemic glomerulonephritis. It is well known that mixed cryoglobulinemia can be present in patients suffering from lupus, but the exact impact that this has on the findings observed on the kidney biopsy of lupus patients is not well established. E-PS-16-008 Late post-transplant focal segmental glomerulosclerosis after covid-19: causal factor or recurrence of primary disease? J. Osuna Soto*, F. Leiva-Cepas, I. Sánchez Ramírez, M.J. Gálvez Medina, R. Ortega Salas *Reina Sofía University Hospital in Córdoba, Spain Background & objectives: Focal segmental glomerulosclerosis (FSGS) is an histopathological pattern common to various underlying aetiologies. Primary FSGS is a podocytopathy that frequently recur on early post-transplant stage. In patients with covid19 and proteinuria, collapsing variant of FSGS is the most common lesion. Methods: We present a 20-year-old man with end-stage kidney disease of unknow ethiology, who underwent kidney transplanta- tion in 2015. He has a history of COVID-19 infection in 2020, and developed FSGS 6 years after transplantation. Results: One of the most common kidney lesion related to SARS- COV2 infection is FSGS, especially in its collapsing and perihi- lar forms. In most cases, recurrence of primary FSGS occurs in the first two years after transplantation, especially within the first days and even immediately after the surgery. However, it also may appear on later stages (>3 months), but being extremely infrequent in its very late form (years). Conclusion: Despite being a very rare event, the possibility of a recurrence of primary FSGS presented in this case (more than 6 years after kidney transplantation) is a plausible option that must be taken into account, given that it is not known the primary under- lying disease of the patient. On the other hand, it would be impru- dent to completely ignore the role that COVID19 infection might have played on the development of the FSGS. E-PS-16-009 Tubulointerstitial nephritis and uveitis (TINU) syndrome: a case series K. Palamaris, A. Stofas*, M. Destouni, A. Patereli, H. Theodoro- poulou, C. Paliouras, K. Stylianou, H. Gakiopoulou *1st Department of Pathology, School of Medicine, National and Kapodistrian University of Athens, Greece Background & objectives: TINU syndrome is a rare, immune- mediated entity, characterized by oculorenal inflammation. Diagnosis requires exclusion of all other causes of tubulointerstitial nephritis (TIN). We present a case series with clinical, laboratory and renal biopsy findings denotative of TINU syndrome. Methods: Five patients experienced ocular and renal manifesta- tions, defined by bilateral uveitis and photosensitivity, along with decline of renal function. In three patients, increased serum creati- nine was accompanied by non-nephrotic range proteinuria. The rest of the laboratory evaluation was normal apart from the presence of elevated CRP and erythrocyte sedimentation rate (ESR) levels. All patients underwent renal biopsy. Results: Histological evaluation revealed interstitial inflammatory infiltration consisting mainly of lymphocytes, with a T-cell predominance, along with several macrophages. Inflammation severity varied among different patients, with some showing scarce foci of immune cell clusters, while others demonstrated a dense, diffuse interstitial infiltration. Interestingly, in one case, a granulomatous pattern, characterized by multiple non-necrotic, ill- defined granulomas was detected. Tubulitis was also encountered in some patients. A divergence was also noted regarding chronicity index, with different levels of tubular atrophy, interstitial fibrosis and global glomerulosclerosis among different cases. Intrestingly, in one patient, electron microscopy revealed scattered granular electron-dense-deposits along some tubular basement membranes creating differential diagnostic issues with anti-TBM and immune- complex TIN. Conclusion: Our cases seem to represent distinct progressive steps within the continuum of disease evolution. Patients with more prominent inflammation might represent a more initial state, while those with more severe chronicity index, probably depict more advanced stages. The predominance of T-cells predicates a cellular-mediated-autoimmune mechanism, as the driving force of the disease occurrence. Interestingly, medical history in one of our S312