Pseudoxanthoma Elasticum (PXE)‐Like Fibers in Patients Without PXE

Abstract

Pseudoxanthoma elasticum (PXE) is an inherited disorder characterised by progressive calcification of elastic fibers in the skin, eyes and cardiovascular system. Skin lesions show distinctive thickened, fragmented elastic fibers in the reticular dermis. PXE‐like fibers have not been described in patients without PXE. We describe 12 patients without known PXE who demonstrated the incidental finding of small numbers of PXE‐like fibers in association with the following conditions: lipodermatosclerosis, granulomatous dermatitis, lichen sclerosus, morphea profunda, erythema nodosum, septal panniculitis, basal cell carcinoma and fibrosing dermatitis NOS. The biopsies were almost exclusively from the lower extremities of elderly women (mean age 73.8). The affected gene in PXE has been recently described as ABCC6 which codes for a member of the ATP‐binding cassette (ABC) family of proteins. The c.3421C>T mutation has been associated with a high risk of coronary artery disease. We describe a novel assay for this genotype employing real‐time PCR of paraffin embedded skin biopsies. Four patients with PXE‐like fibers were tested in this fashion and did not carry this mutation. Our series demonstrates that light microscopic findings associated with PXE are not specific, as PXE‐like fibers can be observed in patients without clinical or genetic evidence of the disease.