Chylous ascites in disseminated Kaposi sarcoma: an unusual manifestation as immune reconstitution inflammatory syndrome

Immune Reconstitution Inflammatory Syndrome Associated Kaposi Sarcoma

People living with HIV (PLWH) with advanced immunosuppression who initiate antiretroviral therapy (ART) are susceptible to the occurrence of an immune reconstitution inflammatory syndrome (IRIS). Although ART is responsible for AIDS- associated Kaposi sarcoma (KS) improvement and resolution, new onset (unmasking KS-IRIS) or sudden progression of preexisting KS (paradoxical KS-IRIS) can occur after a time delay of between a few days and 6 months after the initiation or resumption of ART, even in patients with a low degree of immunocompromise. KS-IRIS incidence varies from 2.4% to 39%, depending on study design, populations, and geographic regions. Risk factors for developing KS-IRIS include advanced KS tumor stage (T1), pre-treatment HIV viral load >5 log10 copies/mL, detectable pre-treatment plasma-KSHV, and initiation of ART alone without concurrent chemotherapy. Both paradoxical and unmasking KS-IRIS have been associated with significant morbidity and mortality, and thrombocytopenia (<100,000 platelets/mm3 at 12 weeks) has been associated with death. KS-IRIS is not to be considered as ART failure, and an ART regimen must be pursued. Systemic chemotherapy for KS in conjunction with ART is recommended and, in contrast with management of IRIS for other opportunistic infections, glucocorticoids are contra-indicated. Despite our preliminary results, the place of targeted therapies in the prevention or treatment of KS-IRIS needs further assessment.

Vascular tumors of the mediastinum

Vascular tumors represent only a sliver of all tumors affecting the mediastinum, but they pose diagnostic challenges due to significant overlap among entities, ever-evolving classification schemes, and the exquisite rarity of some of the entities not only in the mediastinum but in pathology practice as a whole. Most of the vascular tumors are better known to the practice of soft tissue pathology, from which some of the knowledge of clinical behavior can be extrapolated. For example, the stratification of epithelioid hemangioendothelioma (EHE) into two biologically separate categories has effectively translated from the somatic soft tissues to the thorax. For other entities, the effective validation of soft tissue parameters is hindered by the small numbers of reported mediastinal cases. Many of the treatment modalities have also transferred over, with the key differences resting on the difficulty in achieving complete surgical resection for mediastinal tumors as opposed to those in the somatic soft tissues. Accordingly, systemic drug therapies have emerged as attractive options for some of the mediastinal vascular tumors, such as kaposiform hemangioendothelioma (KHE) and Kaposi sarcoma (KS). The categories presented herein mirror the classification scheme set forth by the 5th Edition WHO Classification of Soft Tissue and Bone Tumors. This review focuses on the biologically aggressive vascular neoplasms while limiting discussion of the benign entities to relevant comparisons in the differential diagnoses. While distinguishing among the benign entities has academic importance, in practice, the stakes are far higher for diagnosing the biologically aggressive tumors given their marked heterogeneity in clinical outcomes. Practical advice for problem areas in pathology will be reviewed alongside tumor pathobiology, including the latest in molecular diagnostics.