Immunohistochemical features of cutaneous granulomas in primary immunodeficiency disorders: a comparison with cutaneous sarcoidosis

Background: Cutaneous granulomas can occur in patients with a primary immunodeficiency disorder. In some cases, an infectious cause cannot be revealed. The pathogenesis of these granulomas still remains to be elucidated. The aim of this study was to study differences or overlap between these rare granulomas and sarcoidosis-related granulomas. Methods: Markers for T-cell subsets (CD3, CD4, CD8 and CD45RO), Langerhans' cells (CD1a), macrophages (CD68), B cells (CD20) and NK cells (CD56) were stained immunohistochemically. The amount of CD4+ and CD8+ cells in the granulomas was counted. Results were compared with the CD4+/CD8+ ratio in peripheral blood. Results: In the granulomas of two of three patients with a primary immunodeficiency disorder, the cytotoxic T cells (CD8+) outnumbered the T-helper cells (CD4+) with a counted CD4+/CD8+ ratio << 1. In contrast, the granulomas in the cutaneous sarcoidosis patients showed a predominance of CD4+ cells, with CD4+/CD8+ ratios > 2. Conclusions: A lower CD4+/CD8+ ratio was found in the cutaneous granulomas of patients with a primary immunodeficiency disorder (unclassified combined immunodeficiency, autoimmune lymphoproliferative syndrome and ataxia teleangiectasia) as compared with the patients with cutaneous sarcoidosis. The possible implications of these findings are discussed in this paper.