Giant benign lymphangioendothelioma.

Benign lymphangioendothelioma is a rare locally infiltrative vascular neoplasm, presenting as a slow-growing, asymptomatic, reddish-violaceous plaque. Histopathologically, it is characterized by irregular and thin-walled vascular spaces, lined by a single and discontinuous layer of flat endothelial cells, dissecting dermal collagen bundles. We present the case of a 75-year-old man with a giant benign lymphangioendothelioma, to our knowledge, the largest example described in the literature. The immunohistochemical expression of Wilms tumor 1 gene is useful in vascular lesions to differentiate malformations from proliferative endothelial lesions. In our case, the positivity for WT1 supports the neoplastic nature of this lesion.

Pseudoxanthoma elasticum-like papillary dermal elastolysis: immunohistochemical study using elastic fiber cross-reactivity with an antibody against amyloid P component.

Pseudoxanthoma elasticum (PXE)-like papillary dermal elastolysis is a rare disorder clinically characterized by multiple, asymptomatic nonfollicular papules, yellow or flesh colored, grouped to form plaques with cobblestone appearance. These plaques are arranged symmetrically on the neck and supraclavicular areas of adult or elderly women, closely resembling the lesions of PXE. Histopathologically, the lesions are characterized by a band-like area of elastolysis along the papillary dermis. We report 2 cases of PXE-like papillary dermal elastolysis, in which the anomalies of the elastic tissue were immunohistochemically investigated with an antibody to the amyloid P component. This immunostaining demonstrated a band-like loss of elastic tissue along the papillary dermis. No clumping, fragmentation, or calcification of the elastic tissue was seen. We also review the literature about this rare process and discuss the differential diagnosis with other elastic tissue disorders that may show similar clinical and/or histopathologic findings.

Plaque-like osteoma cutis with transepidermal elimination.

Osteoma cutis is a rare lesion that consists of the presence of bone tissue within the dermis and/or hypodermis. It may be classified as primary osteoma cutis, when bone tissue develops in the skin without any pre-existing lesion and secondary osteoma cutis, which is more frequent and occurs when osseous tissue develops on a pre-existing lesion. We present a case of primary plaque-like osteoma cutis involving the scalp, left forehead and left cheek, which appeared in an adult male. Histopathological study showed several islands of mature osseous tissue involving the full thickness of the dermis. In some areas, there was also transepidermal elimination of bone spicules. We review the literature about previously reported similar cases.