Harlequin fetus with abnormal lamellar granules and giant mitochondria

A study of harlequin ichthyosis using electron microscopy revealed that keratinocytes from the basal to granular cell layers contained giant mitochondria and lacked typical lamellar granules. Instead, dense cored granules (DCG) and particles containing cored granules (PGG) were produced, with most failing to be released from the cytoplasm, leading to the formation of large vacuoles in the stratum corneum. In hair follicles, keratinized cells did not desquamate properly, forming concentric keratin rings around hair, a diagnostic feature of the disease. The study suggested that abnormal lamellar granules contributed to the disease's pathogenesis and that giant mitochondria might be linked to abnormal lipid metabolism in keratinocytes.