Farber disease: pathologic diagnosis in sibs with phenotypic variability.

We describe new pathologic findings in two sibs with Farber lipogranulomatosis. The first child, a 3-month-old boy, presented with only hepatosplenomegaly and had a fulminant clinical course suggestive of malignant histiocytosis. The second child, a 5 1/2-month-old girl, had the typical clinical presentation of Farber disease, with hoarseness and painful swollen joints. At autopsy, storage material was demonstrated in the second child at laryngeal and periarticular subcutaneous sites. Visceral involvement was prominent in both sibs, although not typical of the disease, and included a newly described nephropathy with elevated urine ceramide levels. Liver and spleen contained massive histiocytic infiltrates in association with elevated ceramide levels. Lymph nodes also contained histiocytic infiltrates but without the sinusoidal involvement typical of proliferative histiocytic disorders. These two cases demonstrate new pathologic anomalies in Farber disease, indicating that biochemical analyses of biopsy specimens may be necessary to establish the diagnosis of Farber disease when atypical clinical and morphologic anomalies are present.