CHARACTERISTIC SKIN LESIONS OF PXE

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By Alan E. Simon
Allen N. Sapadin, M.D.
Mount Sinai School of Medicine, New York

In almost all cases, PXE is initially diagnosed from its effects upon the skin, requiring physicians and patients alike to understand the dermatological effects of this disorder.

When elastic tissue in the skin hardens, areas of the skin become a yellow color, forming what are commonly referred to as PXE skin lesions. In milder cases, these appear as yellow marks on the skin, but as the disorder progresses, they can become small bumps (papules}. These bumps may join together to form elevated surfaces of skin (plaques} and, in the most severe cases, the elevated surfaces can become extra folds In the skin. These lesions have been described as "pebbly" and like "chicken skin".

Lesions and extra folds of skin appear in "flexural" areas, meaning those areas where our joints and skin bend most readily. Most commonly, lesions appear on the neck and in the armpit region. Other areas that can be affected include the inside of the elbows (referred to as the antecubital fossae), behind the knees (the popliteal fossae), the wrists, the periumbilical area (the area around the "belly button"), and the groin region. These areas may take on the appearance of prematurely aged skin. Even a 20 year old

patient can look 80 years old in the areas of the extra folds.

In some cases, lesions also arise on the inside of the lower lip. Similar to the lesions on the inner lip, lesions can also appear onother mucosal surfaces inside the body, such as the gastrointestinal tract, the rectum, and the vagina. Although lesions on mucosalsurfaces may visually appear slightly different than those on the skin, beneath a microscope all lesions are identical, consisting offragmented, clumped, calcified elastic tissue.

In milder cases, the lesions on the skin can appear similar to those caused by other dermatological diseases, such as skin lesions secondary to D-penicillamine, certain skin fungi, skin lesions caused by chronic sun exposure, and a PXE-Iike disorder caused by saltpeter. Most apparently, PXE skin lesions resemble a xanthoma, which is a yellow swelling of the skin resulting from excess deposits of fat in one area. The skin lesions of PXE resemble xanthoma so strongly that, while having no other similarities, the disease bears the name "Pseudoxanthoma", meaning "false" xanthoma.

The lesions tend to initially appear during a patient's teens or 20's, but cases have been reported where lesions have been present at birth, while other cases have seen the onset of lesions to occur as late as in a patient's BO's. In some cases of PXE, lesions never appear at all, but other symptoms and microscopic evidence have shown hardened elastic tissue, confirming the presence of PXE. On average, the lesions, tend to progress slowing towards the more severe stages over time, but the trend is unpredictable and it can progress more rapidly in some cases while not at all in others. Furthermore, it is uncommon for these lesions to disappear once they have initially emerged.

Another outwardly observable manifestation of PXE is the presence of angioid streaks in the eyes. While absent in some younger patients, these cracks in a membrane behind the retina are present in nearly all adults with PXE. They are usually observed as gray lines radiating out from the center of the eye. In acute cases, this condition can lead to becoming functionally visually impaired. The severity of ocular disease does not correlate with the extent of skin lesions.

Finally, when PXE does progress to develop extra folds in the skin, plastic surgery techniques have been very successful in removing the extra folds. The removed skin from these procedures is highly valuable for research purposes, and has allowed the medical community to achieve a deeper understanding of the disorder. If any readers of this publication are considering undergoing such a procedure, it would be greatly appreciated if he or she could contact our research facility. We have several years of laboratory experience investigating PXE, and we hope to make great strides in diagnostic and treatment techniques in the coming years.