Expression of WT-1 by the vascular component of acral pseudolymphomatous angiokeratoma of children.

Acral pseudolymphomatous angiokeratoma of children (APACHE) is a disease comprised by a dense dermal infiltrate of B-lymphocytes and T-lymphocytes in which prominent blood vessels with plump endothelium are found. In the past, the lesion was interpreted as a variant of angiokeratoma, a vascular malformation, or a nevus. Currently, most authors consider it to be a type of pseudolymphoma with prominent blood vessels. The latter express CD34 and D2-40, while they lack the expression of Glut-1. The expression of Wilms tumor-1 (WT-1) by APACHE has not yet been studied. In this report, we present a case of APACHE on the right foot of a 4-year-old boy and demonstrate immunoexpression of WT-1 by the blood vessels of the lesion. We also performed serial sections and demonstrated that the WT-1+ vessels with prominent endothelium were D2-40-.

Cutaneous angiolymphoid hyperplasia with high endothelial venules is characterized by endothelial expression of cutaneous lymphocyte antigen.

Two cases in which the presence of cutaneous lesions with a characteristic admixture of lymphoid hyperplasia and vascular proliferation lead to the diagnosis of so-called acral pseudolymphomatous angiokeratoma (APA) of children are reported. Owing to the prominence of its blood vessels, so striking as to be reminiscent of high endothelial venules (HEVs), APA was initially interpreted as a vascular lesion rather than a pseudolymphoma. This resemblance is further compounded by our finding that cutaneous lymphocyte antigen (CLA), an HEV marker, is also expressed in APA epithelioid blood vessels. Consequently, we believe that "cutaneous angiolymphoid hyperplasia with high endothelial venules" (ALH-HEV), which alludes to the dual nature of proliferating elements and the HEV-like phenotype of the vascular component, would be a better denomination for this entity. Additionally, we speculate that ALH-HEV lymphoid hyperplasia self-perpetuates through the transformation of dermal capillaries into HEVs, which would bind non-skin homing lymphocytes expressing L-selectin and promote their local recruitment and recirculation.

A case of angiokeratoma circumscriptum: immunolocalization of matrix metalloproteinase (MMP)-9.

We report a case of angiokeratoma circumscriptum which we have followed for one year. The skin lesion initially showed erythema and then changed to a dark reddish, raised, keratotic nodule. The lesion histologically showed dilated capillaries and hyperkeratosis. Using immunohistochemistry, matrix metalloproteinase (MMP)-9 was localized in the epidermis just under the horny layer, particularly in the hyperkeratotic lesion. The expression of MMP-9 might be related to the hyperkeratotic changes in this lesion.

On the discriminatory value of anti-HPCA-1 (CD-34) in the differential diagnosis of benign and malignant cutaneous vascular proliferations.

The staining pattern of monoclonal antibody anti-HPCA-1 (CD-34) was studied in 95 cases of benign and malignant cutaneous vascular proliferations and compared with other vascular endothelium-associated antigenic markers in paraffin-embedded tissues. The proliferating vessels in 22 cutaneous capillary hemangiomas, 8 lobular capillary hemangiomas, and 1 case of papillary intravascular endothelial hyperplasia stained strongly positively for anti-HPCA-1, and the intensity of the reaction was paralleled by that of factor VIII-related antigen (FVIII), Ulex europaeus lectin-1 (UEA), and vimentin (VIM). The vessels in 10 cases of granulation tissue, 6 cases of cavernous hemangioma, 6 cases of angiokeratoma, 5 cases of angiolymphoid hyperplasia with eosinophilia (epithelioid hemangioma), and 3 cases of bacillary angiomatosis showed a lack of reactivity with anti-HPCA-1 and staining of variable intensity with the other markers. Twenty cases of Kaposi's sarcoma (seven patch, five plaque, eight nodular stage) showed strong labeling with anti-HPCA-1 in small, well-formed vessels scattered among the spindle-cell proliferation, and four of these cases showed focal positivity of scattered spindle cells. Nine cases of cutaneous angiosarcoma, two cases of low-grade epithelioid angiosarcoma, and one case of spindle-cell hemangioendothelioma were negative for anti-HPCA-1 and showed variable reactivity for FVIII and UEA; all cases stained strongly positively for VIM. The results of this study indicate that although anti-HPCA-1 shows a high sensitivity for the staining of normal vascular endothelium, its specificity may be restricted to mature, well-formed vessels, therefore rendering its discriminatory value very limited for the identification of poorly differentiated vascular endothelial neoplasms.

Angiokeratoma corporis circumscriptum naeviforme with transepidermal elimination.

A 5-year-old Japanese boy visited our clinic for treatment of a dark bluish papulonodular lesion on his right thigh. The histopathology of the lesion indicated angiokeratoma corporis circumscriptum naeviforme. Topical antibiotics were prescribed for occasional bleeding from the site. Frequent bleeding started in April of 1992, when erythema and itching were observed around the angiokeratoma. Histopathology of the lesion showed heavy lymphoid cell infiltration around dilated capillaries and irregular acanthosis engulfing dilated capillaries. Interestingly, there were confined masses of red blood cells in the epidermal layer as well as both in and on the horny layer. This is a feature of transepidermal elimination. This transepidermal elimination appeared to be triggered or enhanced by the concomitant contact dermatitis due to topical antibiotics. To the best of our knowledge, this is the first report of angiokeratoma in which the angiokeratoma itself reduced in size through transepidermal elimination, possibly caused by contact dermatitis.