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Peripheral blood lymphocyte appearance in a case of I cell disease
W van der Meer1, B S Jakobs, G Bocca
1Department of Clinical Chemistry, University Hospital Nijmegen St Radboud, 6500 HB Nijmegen, The Netherlands.
Insights
Peripheral blood smear analysis revealed characteristic intracellular inclusions in lymphocytes, aiding in the diagnosis of I cell disease (inclusion cell disease), a severe lysosomal storage disorder.
Area of Science:
- Biochemistry
- Cell Biology
- Genetics
Background:
- Peripheral blood smears are crucial for diagnosing infections and malignancies by examining cell morphology.
- I cell disease (inclusion cell disease) is a fatal lysosomal storage disorder stemming from a defect in mannose-6-phosphate tagging of lysosomal enzymes.
- This enzyme defect leads to mislocalization of lysosomal enzymes and accumulation of macromolecules within lysosomes.
Observation:
- This report details the morphological findings in the peripheral blood lymphocytes of a patient diagnosed with I cell disease.
- Distinctive vacuole-like inclusions were observed within the lymphocytes.
- Notably, these inclusions tested negative for Periodic Acid Schiff (PAS) and Sudan black B staining, differing from previous reports.
Findings:
- The presence of vacuole-like inclusions in peripheral lymphocytes serves as an initial diagnostic clue for I cell disease.
- The observed staining characteristics of these inclusions (PAS and Sudan black B negative) present a unique finding compared to prior literature.
- Diagnosis of I cell disease is typically confirmed by intracellular inclusions, elevated serum lysosomal enzyme activity, and a specific enzyme defect.
Implications:
- Recognizing these specific lymphocyte morphologies on peripheral blood smears can expedite the diagnosis of I cell disease.
- This case highlights potential variations in inclusion staining, emphasizing the need for comprehensive diagnostic approaches.
- Early diagnosis through morphological examination can facilitate timely genetic counseling and management strategies for affected families.
Abstract:
In general, peripheral blood smears are performed to obtain information with regard to various morphological features as an aid in the diagnosis of infection or malignancy. This report presents a patient with I cell disease (inclusion cell disease), a fatal lysosomal storage disorder caused by a defect in an enzyme responsible for the transfer of mannose-6-phosphate ligands to precursor lysosomal enzymes. As a consequence, most lysosomal enzymes are transported outside the cell instead of being correctly targeted into the lysosomes, resulting in the storage of macromolecules in lysosomes. I cell disease, with its heterogeneous clinical presentation, can be diagnosed by the presence of intracellular vacuole-like inclusions in lymphocytes and fibroblasts, high serum lysosomal enzyme activities, and a defect of N-acetylglucosamine-1-phosphotransferase. This report describes the morphological aspects of peripheral lymphocytes in a blood smear of a patient, the first clue to the final diagnosis of I cell disease. The observed vacuole-like inclusions in lymphocytes of this patient were negative for periodic acid Schiff (PAS) and Sudan black B staining, in contrast to earlier reports.