Early post-transplant is the critical phase for the success of hematopoietic stem cell transplantation (HSCT). New viral infections and the reactivations associated with complete ablation of the recipient’s T-cell immunity and inefficient reconstitution of the donor-derived system represent the main risks of HSCT. To date, the pharmacological treatments for post-HSCT viral infection-related complications have many limitations. Adoptive cell therapy (ACT) represents a new pharmacological strategy, allowing us to reconstitute the immune response to infectious agents in the post-HSC period. To demonstrate the potential advantage of this novel immunotherapy strategy, we report three cases of pediatric patients and the respective central nervous system complications after donor lymphocyte infusion.

Pneumocysis jirovecii pneumonia (PJP) is a type of pneumonia originating from the fungus Pneumocystis jiroveci and is a major cause of serious pneumonia in immunocompromised conditions. PJP typically appears as bilateral diffuse pulmonary infiltrates. Granulomatous PJP is an uncommon form of pneumocystis infection, occurring in only 3% to 5% of patients. Calcification is exceptional. We present a 9-month-old boy affected by Severe Combined Immunodeficiency (SCID) that has been diagnosed at the age of 7 months following a lung Pneumocystis jirovecii infection. He underwent a routine total-body magnetic resonance imaging (MRI) prior to an allogeneic hematopoietic stem cell transplantation (HSCT). The MRI showed significant alterations of the pulmonary parenchyma; hence, a computer tomography of the lung was performed showing the presence of 11 calcified granulomatous nodules. We report a unique case of calcified granulomatous PJP in a toddler affected by SCID. Awareness of this rare yet possible presentation in patients with SCID is important given the potential clinical implications when managing a patient undergoing HSCT and it further enhances the importance of advanced radiologic imaging prior to HSCT.