Neuronal ceroid lipofuscinosis. Diagnosis by semithin plastic-embedded sections of peripheral blood lymphocytes from a patient with a normal blood smear.

Neuronal ceroid lipofuscinosis is an important diagnostic consideration in a school-aged child with progressive blindness. Neurologic symptoms and signs may appear late, and the retinopathy is not specific. Ultrastructural abnormalities have been demonstrated in many body tissues, but skin has been claimed to be the most reliable. Light and electron microscopic examinations of WBCs have also been helpful in several instances. In the case reported, the skin biopsy specimen and light microscopy of a peripheral blood buffy coat failed to disclose diagnostic changes. Examination of semithin sections of plastic-embedded peripheral blood provided the answer.