Cystinosis with marked atrophy of the kidneys and thyroid. Histological and ultrastructural studies in an autopsy case.

The eldest autopsied case (a 23-year-old man) of infantile form of cystinosis with uremia and myxoedema was reported. The cystine content per gram wet tissue of various organs was arranged as follows: the thyroid (4.61 mg), kidney (1.71 mg), eye (0.75 mg), spleen (0.65 mg), liver (0.49 mg), and brain (0.016 mg). In polarized light microscopy, cystine crystals were detected in the epithelial cells and epithelial lumina of both kidneys by Wollaston test, and foam cells with cystine crystals were histologically found in the reticuloendothelial and other organs, especially in the bone marrows. Moreover, electron microscopic findings revealed square, rectangular or lozenge-shaped small cystine crystal profiles in osmophilic dense bodies of the histiocytic cells and in the cytoplasm of the foam cells. In some of them, positive reaction for acid phosphatase activity was specifically localized at the periphery of the cystine crystal profiles.