Diffuse dermal angiomatosis: A previously undescribed pattern of immunoglobulin and complement deposits in two cases.

Two cases of diffuse dermal angiomatosis are reported in middle-aged women. This rare disease of unknown origin is characterized by increased dermal angiomatosis and ulceration. The clinical and histologic presentations of the presently reported lesions were typical for this disorder. Endothelial cells exhibited a normal immunophenotype. The perivascular basement membranes showed a distribution of collagen alpha chains typical for blood vessels, but not for lymphatics. Immunohistochemistry revealed other undescribed features. At the site of the clinical lesions, linear and granular deposits of immunoglobulins A and M, and complement were found around the vessels and at the dermal-epidermal junction. The same deposits were also found restricted to the dermal-epidermal junction in the peripheral clinically intact skin. No serological signs of auto-immune disorder were detected in one patient. A monoclonal gammopathy was disclosed in the other patient. A pattern of immunoreactant deposits similar to that disclosed in the two patients was not found in the control specimens, and has not been described so far in other types of vascular hyperplasia and neoplasia. A pathogenic role of these deposits is unsettled and should be further explored.