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Pigmented purpuric eruptions: immunopathologic studies supportive of a common immunophenotype
1Department of Pathology, Stanford University Medical Center, California 94305.
Journal of Cutaneous Pathology
|December 1, 1991
Summary
Pigmented purpuric eruptions (PPE) share a common pathogenesis, likely involving a localized T-cell mediated immune response. This suggests a unified understanding of these diverse skin conditions.
Area of Science:
- Dermatology
- Immunology
- Pathology
Background:
- Pigmented purpuric eruptions (PPE) traditionally classified into four histologic subtypes.
- Recent observations indicate similar clinical behavior across subtypes, leading to grouping under the term PPE.
- The underlying pathogenesis of PPE remains largely unknown.
Purpose of the Study:
- To investigate the immunophenotypic profile of PPE subtypes.
- To elucidate the cellular infiltrate in PPE lesions.
- To understand the common pathogenesis of pigmented purpuric eruptions.
Main Methods:
- Examination of 13 PPE lesion examples (histologic and clinical subtypes).
- Application of a panel of hematolymphoid immunophenotypic markers.
- Analysis of T cell, B cell, and macrophage populations within the infiltrate.
Main Results:
- All examined PPE lesions demonstrated a predominant T cell infiltrate.
- The infiltrate consisted of a mixture of CD4 positive and CD4 negative T cells.
- B cells and macrophages were found to be rare components of the infiltrate.
- Immunophenotypic staining patterns were consistent across different histologic PPE subtypes.
Conclusions:
- Pigmented purpuric eruptions (PPE) represent a group of related conditions with a potentially common pathogenesis.
- The observed T cell infiltrate suggests a cell-mediated immune event.
- Vascular damage and erythrocyte extravasation in PPE are likely secondary to this localized immunologic process.