Pre-engraftment syndrome: clinical significance and pathophysiology.

Abstract

In 2003, the Takaue group observed clinical features such as fever, skin rash and fluid retention that mimicked engraftment syndrome (ES) in cord blood transplantation (CBT) patients who received reduced-intensity conditioning regimens, and referred to this event as an inflammatory syndrome (EIS) (personal communication). Around the same time, we also observed these manifestations in patients following CBT and reported the condition as EIS [1]. Kishi et al. [2] labeled similar symptoms that appeared after reduced-intensity CBT as immune reaction. Based on these observations, we retrospectively analyzed the early toxicities in the period of hematopoietic stem cell transplantation (HSCT) and designated the clinical features mimicking ES (Table 1) as pre-engraftment syndrome (pES) [3]. The rationale of using the name pES was that the signs appeared earlier than those of ES, even though the clinical features of pES in the period were highly similar to those of ES. Since that report on pES, many investigators have tried to establish the incidence, risk factors, and clinical outcomes of pES after CBT. Table 1 Clinical features of syndrome. Clinical significance Many complications attributable to regimen-related toxicities arise during HSCT. The cytoreductive regimens used in conventional HSCT destroy rapidly dividing cell populations, particularly bone marrow (BM) progenitor cells and mucosal epithelial cells. Depletion of these cells can lead to infections as well as defective immune responses during the neutropenic period. Besides the conditioning regimens, the graft itself can contribute to transplant-related toxicities. During the period, transplant physicians sometimes encounter post-transplant events with clinical features similar to those of acute graft versus host disease (aGVHD); these include hyperacute GVHD, ES, and the recently documented pES. The defining features and pathogenesis of GVHD are well understood, but those of hyperacute GVHD, ES, and pES are not. Moreover, the relationships between these post-transplant events are also unclear. The reported incidence of pES ranges from 20% to 77%. Although the risk factors and clinical outcomes of pES are poorly understood, most investigators agree that it is most common after myeloablative conditioning, and is associated with increased risk of aGVHD but not with transplant-related mortality, relapse, or decreased overall survival [4,5]. Among the clinical features of pES, pulmonary manifestations tachypnea, hypoxemia, and pulmonary edema can occur along with other radiographic findings of diffuse ground glass opacities and/or pleural effusion. Brownback et al found that over 50% of patients with pES developed hypoxemia and their chest CT scan and bronchoalveolar lavage findings were consistent with noncardiogenic pulmonary edema. Non-significant trends toward increased mortality have been observed in patients with pES who developed hypoxemia and in those who were treated with corticosteroids [6]. However, we would like to emphasize that clinicians should carefully check for the clinical features of pES, particularly for the pulmonary manifestations. Although pES does not affect transplant outcomes, failure to recognize this syndrome in transplant recipients could result in the recipient being subjected to unnecessary diagnostic procedures or treatments for various suspected causes of the pulmonary complications. Early recognition of pES and treatment with a short course of corticosteroids can also avoid unnecessarily long, empirical treatments that could promote opportunistic infections.