This is a newly described form of kidney transplant acute rejection in 1999, which is not uncommon. It affects about one third of all transplanted kidneys in the first 3 months post transplant. This form of rejection affects the microvascular peritubular capillary area. It is a form of acute antibody mediated rejection (humoral type). However, It lacks the typical fibrinoid necrosis arterial humoral rejection. Histological sections with routine staining may show variable number of scattered neutrophilic tubulitis,
variable number of peritubular and glomerular capillary luminal neutrophils, but they may be no apparent histologic features. The only way to identify with certainty this type of acute rejection is by performing C4d immunostaining which highlights the peritubular capillary area
Important facts you should know about this type of rejection: in about one third of cases, immunostaining for C4d may be the only pathological finding. It could be accompanied by acute tubular interstitial cell mediated rejection in 24-43%. Up to 45% of specimen showing endarteritis, have peritublar capillary C4d immunostianing. It can be misdiagnosed as acute cellular rejection in 25% of cases. This form of rejection can be also seen in chronic rejection
The importance of recognizing such a form of rejection: it is a relatively common type of humoral rejection. It requires an aggressive form of treatment and it has a worse course than cellular rejection, but It carries a better prognosis than the usually type of humoral rejection
In Summary, requesting immunostaining for C4d is an essential part of work up cases for suspected renal transplant rejection, especially in the first 3 months post transplant. However, this form of rejection can occur in chronic rejection. This test is important since it can be the only constant and reliable indicator for kidney transplant rejection
We in the FIRST MEDICAL LAB are determined to bring the best of laboratory tests to
clinical practice in Jordan. Please do not hesitate to contact me for any further inquiries
.Dr. Hussam Abu- Farsakh, M.D
Consultant Pathologist and Cytopathologist
American boards of Anatomic, Clinical Pathology and Cytopathology