A 5-month-old boy presents with extreme irritability, progressive rigidity, opisthotonus, and rapid developmental regression. Fundoscopy shows optic atrophy but no cherry-red spot. Brain MRI reveals symmetric thalamic low attenuation. Enzyme assay shows deficient galactocerebrosidase. Which histological finding is characteristic?

• A Multinucleated globoid cells containing PAS-positive material in white matter ✓
• B Foamy histiocytes with wrinkled tissue-paper cytoplasm in spleen
• C Metachromatic granules in Schwann cells on cresyl violet staining
• D Zebra bodies within lysosomes on electron microscopy of neurons

Explanation

Krabbe disease (globoid cell leukodystrophy) is caused by galactocerebrosidase deficiency. Accumulated psychosine is toxic to oligodendrocytes, and multinucleated globoid macrophages filled with PAS-positive galactocerebroside cluster in demyelinated white matter. Tissue-paper cells define Gaucher disease, metachromatic granules define metachromatic leukodystrophy, and zebra bodies occur in Fabry disease. Absence of a cherry-red spot also separates Krabbe from Tay-Sachs and Niemann-Pick B.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.