Pseudoxanthoma elasticum: clinical, histologic, and genetic studies--a report of two sisters

CASE 1: A 24-year-old black woman was referred to our clinic in September 1999 by the department of dermatology. She was referred to confirm the diagnosis of pseudoxanthoma elasticum (PXE). Her medical history was normal. Dermatologic examination revealed confluent papules that gave the skin a "plucked chicken" appearance on the flexural surfaces in the neck, axillae, clavicle, thigh, and periumbilical area (Figure 1). The patient stated that the changes in her skin had begun in the periumbilical region at about 5 years of age and had since been slowly progressive. Physical examination showed brownish black pigmentation on the left side of the face, left eyelid, and left sclera, which was diagnosed as Nevus of Ota (Figure 2). Her visual acuity was 20/10 in both eyes, with no afferent pupillary defect. Intraocular pressure in both eyes was normal. Slit lamp examination showed no abnormalities. Findings from fundus examination revealed angioid streaks that formed an incomplete ring around the optic disc and anteriorly radiated toward the equator of the globe, multiple calcified drusen-like structures, and "peau d'orange" changes. Skin biopsy (skin tissue from the neck) was taken and the diagnosis of PXE was confirmed. Histopathologic findings revealed calcification of the elastic fibers and abnormalities of the collagen (Figure 3). The patient was not known to have sickle cell anemia or sickle cell trait, and her blood pressure levels had never elevated. Other systemic causes of angioid streaks were excluded by findings from extensive laboratory examination. Her relatives were asked to come in for examination but lived far away. One of the patient's sisters lived in Kinshasa, Africa, however, and is presented in case 2. CASE 2: The 27-year-old sister of the previous patient was examined on April 19, 2000. At examination, she was found to have PXE. Her medical history was significant for systemic hypertension since 1998 and genital hemorrhage. She underwent an ablation of a cyst of her left ovary in 1988. Her ocular history was unremarkable. On physical examination, raised (yellow) papillary lesions, typical of pseudoxanthoma, were found on the neck, axillae, clavicle, thigh, and periumbilical regions. External and anterior segment examinations (of her eyes) were unremarkable. She was found to have a best-corrected visual acuity of 20/10 in both eyes. Intraocular pressure was normal. Funduscopy revealed bilateral angioid streaks, crystalline bodies, and "peau d'orange," but to a lesser extent than in her sister. In both cases, after informed consent, peripheral blood cells were taken and sent for extraction of DNA. Analysis was performed but could not demonstrate the known gene defects of PXE.