title: Morphology of original and transplanted thymuses in severe combined immunodeficiency.
abstract: Twenty-six patients with severe combined immunodeficiency (SCID) were examined. In 20 cases no defect of the biochemical pathways was found; 6 cases showed a deficiency in adenosine deaminase (ADA) activity. In 19 cases histological sections of the thymus were available. In 3 cases, in addition to the original thymuses, transplanted thymic allografts were microscopically examined. The thymus in SCID without abnormality of the ADA pathway showed a uniform dysplastic pattern with only moderate variations related to mode of inheritance and length of survival. The thymus in SCID with ADA deficiency displayed a heterogeneous pattern ranging from almost normal to a completely dysplastic structure, whereas the transplanted thymic allografts presented either a normal or a dysplastic appearance. The morphology of the thymus is not pathognomonic of any given biochemical defect, clinical course, or type of SCID. SCID with apparently normal biochemical pathways probably results from a variety of pathogenetic mechanisms.
mesh_terms: D000243:Adenosine Deaminase / Q000172:deficiency; D005260:Female; D006801:Humans; D007153:Immunologic Deficiency Syndromes / Q000235:genetics / Q000473:pathology*; D007223:Infant; D008297:Male; D013950:Thymus Gland / Q000473:pathology* / Q000637:transplantation; D014184:Transplantation, Homologous
chemical_list: D000243:Adenosine Deaminase