The autopsy of a child aged 21 mth who died of Farber's disease is described. Death was the consequence of extensive pulmonary involvement. This is the 14th description of this disease, and the 11th autopsy case. The ultrastructure of a biopsied s.c. nodule and of fragments of thymus, lung and periarticular nodules fixed shortly after death is described. The typical changes of the disease are present, with a particularly severe lung involvement, infiltration of nearly all the thymus with epithelioid cells, and epithelioid nodules in lymphoid tissue of the intestine and appendix. In the spleen, abnormal cells were mainly present in the subcapsular region. The liver was apparently normal. The typical swollen cells contained inclusions, probably of lysosomal origin, with lipidic lamellae, often paired and frequently showing a marked curvature. These lipids which were surrounded by a strongly stained matrix (Thiery's method) were probably of a mucopolysaccharide nature. Some cells, apparently at an advanced stage, contained very large empty vacuoles, the content of which was dissolved. Biochemical analysis comfirmed the presence of a high level of free ceramides in the s.c. nodules. Farber's disease is thus a lysosomal storage disease, characterized by the nodular aspect of most lesions, their location near the articulations and in the respiratory tract. In this case, the thymus and the lymphoid tissue of the intestine were severely infiltrated. The ultrastructure differs from that of most other lipid storage disease, with some resemblance to Gaucher's disease (glucosyl ceramidosis) and Krabbe's disease lactosyl ceramidosis)., SCOPUS: ar.j, info:eu-repo/semantics/published