Xanthoma disseminatum.

Xanthoma disseminatum is a rare, benign, normolipemic form of non-Langerhans cell histiocytosis affecting the skin and mucous membranes. The cutaneous manifestations consist of hundreds of papules that are red – brown at first and then become yellowish. The papules symmetrically involve the eyelids, trunk, face and proximal extremities and in flexures and folds, tend quickly to merge, forming soft plaques. It is frequently associated with diabetes insipidus. Biopsy specimens show a mixture of histiocytes, foam cells, and inflammatory cells. Later, foam cells predominate and Touton giant cells are frequently present. This chronic disease has no known established treatment.

Stewart-Treves syndrome: a rare entity.

Stewart-Treves syndrome is a rare, deadly cutaneous angiosarcoma that develops in long - standing chronic lymphedema. Most commonly, this tumor is a result of lymphedema induced by radical mastectomy to treat breast cancer. Stewart-Treves syndrome occurs in 0.5% of patients, who survive mastectomy for more than 5 years. The mean age at appearance of the angiosarcoma is 62 years, and the mean interval between mastectomy and the appearance of the tumor is 10.5 years. The exact pathogenesis is not known so far. On histopathology, vascular channels infiltrate the normal structures in a disorganized fashion, as if trying to line every available tissue space with a layer of endothelial cells. The prognosis is poor as it is very aggressive. Only early diagnosis and prompt radical excision with or without adjuvant radiotherapy, can promote survival.

Hydroa vacciniforme: a very rare photodermatosis.

Hydroa Vacciniforme (HV) is a rare, acquired and chronic paediatric disorder that is characterized by photosensitivity and recurrent crops of skin lesions on sun-exposed skin, such as the face, ears and hands that heal with vacciniforme scarring. The pathogenesis of HV is unknown. No chromosome abnormality has been identified so far. HV patients have no abnormal laboratory results. The histopathologic features are distinctive and demonstrate intraepidermal multilocular vesicles and cellular necrosis. Most cases remit spontaneously by late adolescence.