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Multicentric reticulohistiocytosis. Electron microscopic and ultracytochemical studies
Abstract:
Lesions from a patient affected with multicentric reticulohistiocytosis (MR) were studied by ultracytochemical techniques to determine the relationship of PAS-positive materials and/or acid phosphatase (AP) activity to electron-dense granules found in the large mononucleated or multinucleated giant cells that are characteristic of this entity. The lead phosphate reaction products that mark the sites of AP activity were found in the electron-dense granules. The granules were also PAS positive by the periodic acid-thiosemicarbazide-silver proteinate method. These findings suggest that the PAS-positive and diastase-resistant materials in the large mononucleated or multinucleated giant cells of MR are not phagocytized materials but are pre-existing lysosomes.
Insights
Multicentric reticulohistiocytosis (MR) giant cells contain PAS-positive, diastase-resistant granules. Ultracytochemistry reveals these granules are pre-existing lysosomes, not phagocytized material.
Area of Science:
- Cell Biology
- Pathology
- Histochemistry
Background:
- Multicentric reticulohistiocytosis (MR) is characterized by large mononucleated and multinucleated giant cells.
- The nature of the PAS-positive and acid phosphatase (AP)-active materials within these cells has been debated.
Observation:
- Ultracytochemical techniques were employed to investigate the relationship between PAS-positive materials, AP activity, and electron-dense granules in MR giant cells.
- Lead phosphate reaction products, indicating AP activity, were localized within these electron-dense granules.
- The granules also demonstrated positive staining with the periodic acid-thiosemicarbazide-silver proteinate (PAS) method.
Findings:
- The study found that the electron-dense granules in MR giant cells are both PAS-positive and acid phosphatase-active.
- These findings indicate that the PAS-positive and diastase-resistant materials are intrinsic to the cells, not foreign substances.
Implications:
- The research suggests that the characteristic granules in MR giant cells are pre-existing lysosomes.
- This clarifies the cellular origin of these materials, differentiating them from phagocytized substances.
- Understanding the lysosomal nature of these granules contributes to the histochemical characterization of multicentric reticulohistiocytosis.