Ultrastructure of skin biopsy specimens in lysosomal storage diseases: common sources of error in diagnosis.

Common sources of error in the diagnosis of lysosomal storage diseases by ultrastructural examination of skin specimens have been identified in a series of biopsies from 72 patients. Four principal factors have emerged as leading pitfalls and sources of error in diagnosis. First, the skin biopsy technique itself may lead to alterations of normal skin ultrastructure. Second, artifacts may be produced during fixation and preparation of tissue for electron microscopy. Third, cellular organelles and structures normally present in human skin may be mistakenly interpreted as pathological. Fourth, the use of cultured skin fibroblasts for ultrastructural identification of storage material is often accompanied by artifacts induced in tissue culture and is not recommended. Recognition of these common problems may aid interpretation of the fine structure of skin abnormalities. Furthermore, when skin biopsy specimens are used as the primary source of diagnostic material, correlation of both skin ultrastructure and assay for specific lysosomal enzymes in cultured dermal fibroblasts will facilitate diagnostic accuracy.