Acral pseudolymphomatous angiokeratoma of children: immunohistochemical and clonal analyses of the infiltrating cells

Abstract

Background: Acral pseudolymphomatous angiokeratoma of children (APACHE) is a disorder characterized clinically by red nodules and histopathologically by a massive subepidermal lymphohistiocytic infiltrate. Although it was initially thought to be a vascular nevus, it has never been regarded as a pseudolymphoma.

Case report: We report a 7-year-old-girl with small red nodules on the dorsum of the right foot and a 73-year-old man with asymptomatic brown-red nodules on the lower extremities.

Results: Histopathologic examination revealed a massive lymphohistiocytic infiltrate with plasma cells, some eosinophils, or a multinucleated giant cell immediately beneath the epidermis. Thick-walled vessels were observed in the infiltrate. These characteristics are identical to those of acral pseudolymphomatous angiokeratoma of children. The infiltrate was composed mainly of equal numbers of CD4+ or CD8+ T cells and equal numbers of B cells stained for kappa or lambda light chains. PCR amplification of rearranged immunoglobulin heavy chain genes or T-cell receptor gamma genes showed no evidence of clonality, suggesting that these infiltrates were polyclonal both for B and T cells.

Conclusions: Our data support the idea that this disorder represents a reactive process. The modified term 'papular angiolymphoid hyperplasia' would define this disorder more appropriately.