Pseudoxanthoma elasticum and skin: Clinical manifestations, histopathology, pathomechanism, perspectives of treatment.

Pseudoxantoma elasticum (PXE), also known as Groenblad-Strandberg syndrome, is a rare heritable disease with an estimated prevalence of 1:50,000 in the general population. PXE is considered a prototype of multisystem ectopic mineralization disorders and it is characterized by aberrant mineralization of soft connective tissue with degeneration of the elastic fibers, involving primarily the eyes, the cardiovascular system, and the skin. Cutaneous lesions consist of small, asymptomatic, yellowish papules or larger coalescent plaques, typically located on the neck and the flexural areas. PXE is caused by mutations in the ABCC6 (ATP-binding cassette subfamily C member 6) gene that encodes a transmembrane ATP binding efflux transporter, normally expressed in the liver and the kidney; however, the exact mechanism of ectopic mineralization remains largely unknown. The histological examination of cutaneous lesions, revealing accumulation of pleomorphic elastic structures in middermis, is essential for the definitive diagnosis of PXE, excluding PXE-like conditions. PXE is currently an intractable disease; although the cutaneous findings primarily present a cosmetic problem, they signify the risk for development of ocular and cardiovascular complications associated with considerable morbidity and mortality. The purpose of this review is to present a comprehensive overview of this rare form of hereditary connective tissue disorders, focus on the pathogenesis, the clinical manifestation, and the differential diagnosis of PXE. Emphasis is also placed on the management of cutaneous lesions and treatment perspectives of PXE.

IgG4-related sclerosing disease: an emerging entity frequently misdiagnosed.

IgG4-related sclerosing disease, a multiorgan system disease that has been identified in the last 10 years, is a fibroinflammatory condition with a marked propensity to manifest itself as mass forming lesions characterized by three main histological features (sclerosis, obliterative phlebitis and lymphoplasmacytic infiltrate) and by the presence of abundant IgG4+ plasma cells, frequent elevation of serum IgG4 and a dramatic initial response to steroid therapy. The aim of this mini-review is to increase the capacity to identify the characteristic features of IgG4-related sclerosing disease in specific organs and in two newly proposed entities (urethral caruncle and paratesticular fibrous pseudotumor) using biopsy specimens and methods of counting IgG4. In addition we examine the relationship between IgG4-related sclerosing disease and malignancy. In fact, an increased ability to recognize the characteristic features of IgG4-related sclerosing disease would play an extremely important role in avoiding unnecessary surgery in favor of initiating corticosteroid therapy.