Pseudoxanthoma Elasticum

Department of Dermatology, Venereology and Leprosy, Dr RP Govt Medical College,
Kangra (Tanda) 176 001, HP, India.
Email: [email protected]
 

A 15-year-old boy of non-consanguineous parentage had progressively increasing loose folded skin of three year duration. Skin over neck, shoulders, chest and axillary folds showed yellowish pebbly plucked-chicken skin appearance and large well-defined atrophic plaques over neck having erythematous and ragged margins studded with discrete keratotic papules which would bleed on removal (Fig 1). The trunk skin was soft, lax and had hanging redundant folds (Fig 1). Hair, nails, mucous membranes and other systemic examination were normal, and ophthalmoscopy showed no angioid streaks. Laboratory investigations including hemogram, serum biochemistry, urinalysis, chest X-ray, ECG, echocardiography and doppler studies were normal. Histology showed normal epidermis, swollen, irregularly clumped degenerated faintly basophilic and calcified dermal elastic fibers, and mixed inflammatory cells. He was diagnosed having pseudoxanthoma elasticum.

Fig.1 (a) Perforating lesion of pseudoxanthoma elasticum (arrow) showing central atrophy and discrete keratotic papules over the erythematous margins and central atrophic skin. (b) Folded, lax, redundant abdominal skin.

Pseudoxanthoma elasticum (PXE) is an uncommon autosomal recessive disorder of generalized elastorrhexis and calcification of elastic fibers in the dermis, Bruch’s membrane and arterial lamina. Spontaneous perforating skin lesions with transepidermal elimination of fragmented elastic fibers may develop manifesting as hyperkeratotic papules. PXE needs be differentiated from yellow-orange plaques of localized or generalized plane xanthomas seen associated with abnormalities of lipid metabolism, and juvenile elastoma wherein skin lesions show thickened elastic fibers histologically. A PXE-like clinicohistopathologic syndrome in patients with b-thalassemia, sickle cell anemia or sickle thalassemia has late onset and is acquired as consequences of the primary disease. In view of clinical heterogeneity, the diagnosis of PXE requires all three major criteria; 1) The characteristic "plucked-chicken-skin" appearance that becomes evident by second decade and progressively becomes lax and redundant, 2) characteristic histology and 3) angioid streaks, symmetric tears in the Bruch’s membrane, in adults aged >20 years or, 2 minor criteria; 1) characteristic histological changes in non-lesional skin and 2) history of PXE in first degree relatives. Management includes timely photocoagulation of retinal hemorrhage to prevent choroiditis and visual loss, prevention and management of coronary occlusion, gastrointestinal or cerebral bleeds which may end fatally otherwise, cosmetic improvement and genetic counseling. Identification of mutations in the ABCC6 gene (chromosome locus 16q13.1) encoding MRP6 protein provides prenatal and pre-symptomatic testing in families at risk.