Kidney transplant pathology

Biopsy of the transplanted kidney plays an important role in the care and treatment of patients after kidney transplantation. Today the renal biopsy is a standard procedure which is performed early after renal transplantation in the case of a primary non-functioning graft or a significant rise in serum creatinine. On the other hand, a kidney biopsy is performed if an acute or creeping rise in serum creatinine or acute onset of proteinuria or erythrocyturia is observed during follow-up. Furthermore, zero biopsies or intraoperative biopsies of the graft are important in order to obtain information about the initial quality of the graft. This is particularly important in view of the shortage of donor organs and the resulting necessity to accept increasingly marginal organs, such as for example in the ESP program. In addition, an increasing number of transplant centres perform protocol biopsies, i.e. biopsies that are not based on clinical indication, but are performed at a certain time point after transplantation to detect subclinical rejections as well as histological alterations pointing to chronic allograft damage. Additionally, there is much scientific interest in protocol biopsies.     

Gastrointestinal pathology in transplant patients

The assessment of gastrointestinal (GI) specimens from transplant patients is complicated by the wide range of potentially rare pathologies that may be found in this clinical setting. Acute GI graft‐versus‐host disease (GvHD) is characterized by epithelial cell apoptosis, although there is increasing recognition that acute and/or chronic inflammation may also be present. By contrast, thus far there are no histological features known to be specific to chronic GI GvHD. Mycophenolate mofetil colitis may mimic both GvHD and inflammatory bowel disease, whereas both cytomegalovirus (CMV) and adenovirus infections can cause gland apoptosis. Post‐transplant lymphoproliferative disorder should be considered if a Crohn's‐like histological picture is seen, and granulomas in biopsies from umbilical cord blood recipients should raise a suspicion of cord colitis syndrome. Finally, the GI tract may be involved directly or indirectly by the disease that originally required haematopoietic stem cell or liver transplantation.     

New developments in renal transplant pathology

The renal transplant biopsy plays a central role in the diagnosis of renal allograft dysfunction; in particular in differentiating immune-mediated rejection from various infective, ischaemic and toxic pathologies. Recent advances have been made in refining the histological criteria for rejection diagnosis. The Banff’97 classification of renal allograft pathology has gained almost universal acceptance. In this classification, acute rejection is divided into three main types, tubulointerstitial, vascular and severe vascular, that differ in response to anti-rejection therapy and long-term prognosis. There remain, however, a number of challenges; interpretation of biopsies showing borderline changes, the diagnosis of humoral rejection and differentiating rejection from interstitial nephritis associated with viral infections present specific problems. There are potential applications for new molecular and immunohistochemical techniques in these areas. Other challenges arise from the application of the Banff classification. Recent validation studies have indicated that the reproducibility of some Banff criteria is low and that there are a number of histological features, not included in the Banff schema, that may be useful in rejection diagnosis.New roles for the transplant biopsy are developing in the management of patients with stable graft function, as indicated by measurement of serum creatinine. Protocol biopsies performed at regular intervals in the early post-transplant period may be used to predict subsequent development of chronic allograft nephropathy, the major cause of graft loss. The interpretation of these biopsies may be refined using morphometric techniques and immunohistochemistry for cytokines and matrix components. Protocol biopsies may also be used to diagnose sub-clinical rejection, and early evidence indicates that treatment of these histological rejections improves long-term graft outcome. The role of the transplant biopsy will continue to evolve with greater use of organs from marginal donors, improved understanding of the processes of graft injury and fibrosis, and the introduction of new immunosuppressive regimens.     

Cardiovascular pathology in renal transplant recipients

Various cardiovascular complications are among the major causes of mortality in renal transplant recipients. The authors examined the cardiovascular findings from necropsy of 18 renal transplant patients. All but three of the patients showed one or more pathological abnormalities. Five patients exhibited severe coronary arteriosclerosis with acute myocardial infarction with a history of myocardial infarction noted in four patients. In addition, one patient showed moderate and two showed mild coronary arteriosclerosis. Also prevalent were left ventricular (LV) hypertrophy (10/18), right ventricular (RV) hypertrophy (7/18), LV dilatation (4/18), RV dilatation (8/18), left atrial dilatation (3/18), and right atrial dilatation (6/18). Valvular abnormalities consisted of dilatations of mitral ring (1/18), pulmonic valve (2/18), and tricuspid valve (3/18). Pericarditis was found in two patients and aortic atherosclerosis in ten patients. Findings on routine chest roentgenograms and electrocardiograms did not always correspond with the anatomical findings noted on necropsy examination. The results demonstrate a marked increase in the incidence of various cardiac abnormalities in renal transplant recipients.     

Pulmonary pathology in renal transplant recipients

Studies of the lungs have revealed multiple functional and histopathological abnormalities in patients with chronic renal failure, but data following renal transplantation are extremely limited. We examined postmortem data from 20 transplant patients and found pulmonary abnormalities in most patients. The number of pulmonary abnormalities noted in patients with poor transplantation, averaged 5.3 per patient. The corresponding number was significantly less (3.4 per patient) in the group with good transplant renal function, surviving more than one year after transplantation. Pulmonary calcification, fibrosis, and hemosiderosis were found in several patients in the former group but in none of the latter group. This observation suggests reversibility of these pulmonary abnormalities with successful renal transplantation.     

Renal pathology of the fowl--a review

On the basis of published literature and some original observations a comprehensive review is presented of the current concept of renal diseases in the fowl. All aspects of this important but much neglected subject are considered including autolysis, intoxications, inflammatory and degenerative conditions, specific viral diseases, gout, congenital abnormalities and neoplasms. The aetiology and pathogenesis of some forms of avian kidney disease are well understood but there are large gaps in our knowledge on others.     

Specialised pediatric pathology service

Leningrad Regional Children's Bureau of Pathology was established in May 1992. The program of this bureau consisted of: revealing causes of early and late abortions; assessment of ultrasound diagnosis of congenital deficiencies of fetus development and clinical assessment of chronic placental insufficiency; pathogenetic explanation of intrauterine fetuses death; prognosis of neonatal pathology; systemic analysis of dynamics of perinatal, natal and infant mortality; organisation of independant expertise of medical causes of reproductive losses. The following principles in the work of the bureau were established: 1) mass investigation of placentas of newborns; 2) use of urgent pathomorphological diagnosis which allows to present information about placentas not later than 24 hrs after the delivery; 3) complex investigation of placentas with the use of various methods; 4) systemic informational analysis of placental pathology; 5) constant updating of physicians knowledge in the field of practical placentology. Results of mass placentas investigation show a principal pathogenetic role of ascending infection in perinatal mortality in opportunistic pathogenic microflora with the development of inflammatory responses in the system mother-placenta-fetus.     

Renal pathology in von Hippel-Lindau disease

Von Hippel-Lindau disease, a rare autosomal disorder, is associated with multiple lesions, including a high incidence of renal lesions and CNS hemangioblastomas. Renal lesions have traditionally been classified as either benign cysts or solid renal cell carcinomas with or without cystic degeneration. We examined seven kidney specimens from four patients with von Hippel-Lindau disease. We found that renal cysts form a histopathologic continuum ranging from benign cysts (with one to two cell layers of bland epithelium), atypical cysts (demonstrating epithelial hyperplasia with or without mild cytologic atypia), to malignant cysts harboring renal cell carcinoma. The presence of atypia or foci of carcinoma does not correlate with cyst size. Lesions that appear radiologically or grossly solid range from conventional solid renal cell carcinoma, sometimes evidencing cystic degeneration, to lesions that are predominantly hyalinized, fibrotic nodules. In contrast to simple cysts occurring in the general population, which are virtually always benign, renal cysts in patients with von Hippel-Lindau disease may contain occult carcinoma. Radiologic evaluation, visual inspection at surgery, and even frozen section analysis of cyst lesions cannot be relied on to detect small foci of carcinoma. The spectrum of pathologic changes and the multicentricity of the renal lesions in von Hippel-Lindau disease complicate the radiologic evaluation and surgical management of these patients.