There are more than 50 lysosomal storage disorders. Most of them are inherited as autosomal recessive genetic defects. The late onset and slow progression of disease are the specific features of lyso - somal storage disorders. The disorders manifest with muscle weakness, developmental delays. Later clinical features are: organomegaly (especially liver and spleen, heart), coarse facial features, joint or skeletal deformities. Usually, no metabolic decompensation occurs. For the confirmation of the diagnosis it is essentail specific enzyme studies, detection of the mutations of genes. But when it’s no benefit, the bone marrow or blood film investigation can help suspect lysosomal storage disorders. A range of metabolic diseases can result in abnormal accumulation of metabolic byproducts, resulting in abnormal lymphocyte cytoplasmic vacuolation and other morphological changes of lymphocytes, which can be identified on routine blood film or bone marrow examination and electron microscopic examination. Few small vacuoles in the lymphocytes can be seen in: Pompe’s disease, Wolman’s disease, Niemann-Pick disease type A and C. Many small vacuoles in the lymphocytes are specific for: GM1 gangliosidosis, mucolipidosis type I, Salla disease, galac- tosialidosis, neuronal ceroid-lipofusci- nosis (CLN3)). Eosinophils are abnormal in Salla disease and infantile GM1 gangliosidosis. Giant granules in leukocytes occur in Chediak-Higashi syndrome. Blood or bone marrow morphologic investigation can be very informative for suspection, differentiation and confirmation of the lysosomal storage disorders diagnosis.
