Lymphoproliferative disorders in the immunosuppressed

Benign lymphoproliferative disorders in the immunosuppressed patient: an update

Immunosuppressed patients may be affected by a wide range of lymphoproliferative disorders (LPDs) ranging from self-limiting disorders to malignant lymphoid proliferations. These LPDs may be associated with systemic immune disorders, develop following organ transplantation or occur in the background of other forms of iatrogenic immunosuppression. Lymphotropic viruses, including Epstein-Barr virus (EBV) and human herpesvirus-8 (HHV8), have been associated with the pathogenesis of distinct LPDs. The resulting classification of this group of disorders is very complex and inconsistent, with several new and emerging entities. Consequently, the diagnosis of an LPD, especially in an immunosuppressed patient, and its subsequent clinical management usually represent an important pitfall in daily clinical and pathology work. Therefore, the aim of this review was to use the available literature to describe the clinicopathological features of the most important benign LPDs that may be diagnosed in the head and neck region of immunosuppressed patients. Original clinical and microscopic images were used to illustrate some of these entities.

Pulmonary complications in the non-HIV immunocompromised patient

The incidence of non-HIV immunocompromised patients is increasing. This is primarily due to improved immunosuppressive regimes for autoimmune diseases and also increases in stem cell transplantation. Pulmonary complications are a major cause of morbidity and mortality in these patients. Imaging is frequently used to assess these complications and to streamline therapies, as microbiological and/or pathological diagnosis can often be difficult, invasive, or protracted. This review provides the reader with a structured approach to interpret the imaging findings and differentiate between different infective and non-infective complications in these patients.

Posttransplant lymphoproliferative disorders

Posttransplant lymphoproliferative disorders (PTLDs) are a group of diseases that range from benign polyclonal to malignant monoclonal lymphoid proliferations. They arise secondary to treatment with immunosuppressive drugs given to prevent transplant rejection. Three main pathologic subsets/stages of evolution are recognised: early, polymorphic, and monomorphic lesions. The pathogenesis of PTLDs seems to be multifactorial. Among possible infective aetiologies, the role of EBV has been studied in depth, and the virus is thought to play a central role in driving the proliferation of EBV-infected B cells that leads to subsequent development of the lymphoproliferative disorder. It is apparent, however, that EBV is not solely responsible for the “neoplastic” state. Accumulated genetic alterations of oncogenes and tumour suppressor genes (deletions, mutations, rearrangements, and amplifications) and epigenetic changes (aberrant hypermethylation) that involve tumour suppressor genes are integral to the pathogenesis. Antigenic stimulation also plays an evident role in the pathogenesis of PTLDs. Plasmacytoid dendritic cells (PDCs) that are critical to fight viral infections have been thought to play a pathogenetically relevant role in PTLDs. Furthermore, regulatory T cells (Treg cells), which are modulators of immune reactions once incited, seem to have an important role in PTLDs where antigenic stimulation is key for the pathogenesis.