A NGIOMA SERPIGINOSUM TYPICALLY PREsents as a small geometric arrangement of red puncta on a macular red to violaceous background, although limited case reports describe more extensive involvement. We describe 2 women with extensive retiform and confluent erythematous patches on the trunk and extremities (Figure 1A [patient 1] and Figure 1B [patient 2]). Of note, both patients stated that the appearance of their lesions worsened with increased cold and improved with warmth exposure. Dermoscopy demonstrated sheets of discrete red lagoons (Figure 2A [patient 1] and Figure 2B [patient 2]). Reflectance confocal microscopy revealed multiple dilated vascular spaces in the superficial dermis, arranged perpendicular to the epidermis, with a deeper vascular plexus parallel to the epidermal surface (Figure 3A [patient 1] and Figure 3B [patient 2]). Within the vascular spaces, we visualized large numbers of poorly refractile small cells (consistent with erythrocytes) moving rapidly in the central portion of the vessel lumen and smaller numbers of larger, brightly refractile cells (consistent with leukocytes) at the periphery of the vascular lumen (video 1 and video 2 [http: //www.archdermatol.com]). Pathologic examination confirmed the presence of marginalized leukocytes in the absence of perivascular inflammation. Also, both cases demonstrated increased dermal mucin, which, to our knowledge, has not previously been reported in association with this condition. The adhesion of leukocytes to the vascular endothelium is quite striking; similar findings, particularly underlying superficial ulceration, have been reported in basal cell carcinoma. Visualization of marginalized leukocytes has not been reported in other benign vascular conditions, such as cherry angiomas and psoriasis. Appreciation of a deeper vascular plexus arranged parallel to the epidermal surface, with vertical feeder vessels, could explain the counterintuitive clinical improvement with exposure to warm temperatures. Dilatation of the deeper plexus could effectively drain the superficial vessels, resulting in diminished prominence of the retiform patches. A B