Table 1.

Differential diagnosis of PXE-like cutaneous findings

Disease/Condition	Clinical and genetic associations	References
Pseudoxanthoma elasticum	Classic findings of yellowish papules and inelastic skin, together with ocular and vascular involvement, due to mutations in the ABCC6 gene^a)	2, 12
Vitamin K-dependent coagulation factor deficiency	Loose and sagging skin with yellowish papules, with bleeding disorder, due to select mutations in the GGCX gene^b)	5-7
Hemoglobinopathies	Cutaneous and ocular findings consistent with PXE in ~25% of patients with β-thalassemia and sickle cell anemia^c)	4, 9, 21
Metabolic calcification disorders	Cutaneous lesions similar to those in PXE in patients with idiopathic hypercalcemia, hyperphosphatemia, tumoral calcinosis and calciphylaxis^d)	1, 22
Drug-induced	Long-term sequela of D-penicillamine treatment, and in a limited number of cases with eosinophilia-myalgia syndrome due to contaminated L-tryptophan ingestion^e)	8, 23
Environmental exposure	Percutaneous absorption of salpeter (calcium nitrate) from fertilizers^f)	10

THIS STUDY
Generalized arterial calcification of infancy	PXE-like skin findings associated with extensive mineralization of vascular connective tissues due to a homozygous mutation in the ENPP1 gene

^a)

>300 mutant alleles of the ABCC6 gene have been disclosed.

^b)

In one family, individuals compound heterozygous for one mutation in GGCX and one mutation in ABCC6 were noted, indicating digenic inheritance of PXE.⁶

^c)

The absence of ABCC6 mutations has been documented in some cases.

^d)

PXE-like cutaneous findings have been reported in a limited number of patients with each disorder.

^e)

Cutaneous findings clinically reminiscent of PXE in association with elastosis perforans serpiginosa have been described in patients undergoing long-term treatment of Wilson’s disease or cystinuria with D-penicillamine; these lesions show elastic fiber abnormalities but no mineralization, and have been dubbed as pseudo-pseudoxanthoma elasticum.

^f)

Findings clinically and histologically similar to those in PXE were described in the exposed areas of skin in farmers without systemic manifestations.