Autopsy Findings Of The Thymus In Cases Of Fatal Paediatric Severe Acute Respiratory Conditions At The Kenyatta National Hospital Farewell Home.

Abstract

Background: The thymus, together with the bone marrow plays a major role in primary lymphopoiesis. It is retrosternal organ that weighs up to 15 grams in the paediatric population. Physiologically the thymus is responsible for T-helper and T-cytotoxic cell maturation together with their immune regulatory functions. It then gradually reduces in size and function from teenage with complete atrophy in adulthood. Thymus size and function is influenced by various factors i.e. genetics, nutritional status and infections. In thymic pathology, paediatric health is adversely affected as the thymus plays a critical role in immune homeostasis from birth to adolescents; particularly involving infectious agents. A paediatric respiratory aetiology surveillance study that was completed in 2016 at The Kenyatta National Hospital demonstrated thymic hypoplasia in up to 60% of the autopsies conducted. Thus begging the need evaluate the thymic anatomy and affection of function in children dying from infections and malnutrition. Objectives: The main objective of this study was to describe the thymic autopsy findings and clinical correlations among fatal paediatric severe acute respiratory infections at the Kenyatta National Hospital farewell home from 2014-2016. Study design: Cross-sectional descriptive study using autopsy samples from 64 decedents that were obtained from a previous paediatric respiratory aetiology surveillance study that was carried out at The Kenyatta National Hospital from 2014-2016. Setting: The University of Nairobi’s Anatomic Pathology Core Histopathology laboratory. Methodology: The formalin fixed and paraffin embedded thymic and splenic tissue blocks were sectioned and stained using routine hematoxylin/eosin stain. The cellular populations were xi assessed by staining for the distribution and quantity of T lymphocytes, B lymphocyte and NK cells using CD3, CD5, CD20, CD79a, PAX5 and CD56 immunohistochemical stains. Slides were examined with the help of my supervisors. Standard operating procedures was applied in specimen handling and processing. Specific clinical data i.e. age, weight, I.P number, mid-upper arm circumference and lymphocyte differential counts were obtained from the previous PRESS study.