Abstract

Pseudoxanthoma elasticum (PXE) is a genetic disorder which predominantly affects the elastic tissue of the skin, eyes, and arteries. PXE is due to homozygous or compound heterozygous mutations in the ABCC6 gene, which encodes the cellular transmembrane transport protein ABCC6. We report a 59-year-old female who presented with gradually worsening loose bumpy skin since age 22. Her family history was notable for lax axillary skin in the patient's sister and nephew as well as premature death of a sibling due to myocardial infarction. There were no symptoms to suggest claudication or angina. There was no personal or family history of ophthalmologic abnormalities. Physical exam revealed lax and thickened neck skin, containing multiple yellowish papules and plaques. On the upper extremities, there were subtle yellowish papules in the antecubital fossae and fewer in the axillae. Groin skin was lax with multiple yellowish papules. Radial pulses were normal. Dorsalis pedis pulses could not be located with Doppler ultrasound. Posterior tibial pulses were diminished. On dilated examination of eyes, no angioid streaks were noted and no macular changes were present. Punch biopsy from the lesional skin on the posterior neck from our patient and two other family members showed clumped and calcified refractile elastic fibers embedded in a hyalinized collagenous stroma spanning the reticular dermis. Both Von Kossa and Weigert’s stains highlighted the calcified elastic fibers, supporting the diagnosis of PXE. However, genetic testing for mutations in the ABCC6 gene was negative. She was informed of the prognosis and recommendations to follow with ophthalmology and cardiology annually. This family with apparent PXE showed the unique histologic finding of hyalinized collagen surrounding the diagnostic histopathologic findings and the absence of angioid streaks, a diagnostic hallmark of PXE in this age group.

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