Expression of Peripheral Node Addressins by Plasmacytic Plaque of Children, APACHE, TRAPP, and Primary Cutaneous Angioplasmacellular Hyperplasia.

Abstract

High-endothelial venules are a common feature of 3 types of cutaneous pseudolymphomas: pretibial lymphoplasmacytic plaque (PLP) of children, acral pseudolymphomatous angiokeratoma of children (APACHE), and T-cell rich angiomatoid polypoid pseudolymphoma (TRAPP). In addition, primary cutaneous angioplasmacellular hyperplasia (PCAH) overlaps with these other 3 conditions. We intend to study the expression of peripheral node addressins in PLP, APACHE, TRAPP, and PCAH. We studied 1 case of PLP, 2 cases of APACHE, 2 cases of TRAPP, and 2 cases of PCAH. Immunostainings for MECA-79 and WT-1 were obtained in all cases. All cases showed a dense lymphohistiocytic dermal inflammatory infiltrate with abundant plasma cells. In addition, HEV were prominent in all cases. Cases of PLP, APACHE, and TRAPP expressed MECA-1. Cases of PCAH did not express MECA-1. Although PLP, APACHE, and TRAPP seem to fall under the same morphologic spectrum with different clinical representations, PCAH seems to be a different entity, with histopathologic peculiarities and a different immunophenotype.