Phototoxic skin disorders in renal failure:
Patients with renal failure or ESRD secondary SLE can have a photosensitive skin rash.
Discoid Lupus Erythematosus (DLE); these lesions are thick and scaly, plug the hair follicles, appear usually on surfaces of the skin exposed to sun (but can occur in non-exposed areas), tend to scar, and usually do not itch.
Acute Cutaneous Lupus Erythematosus (ACLE); Confluent erythema and edema, erythematous macules and papules that eventually become confluent and occur in areas exposed to the sun and can be triggered by sun exposure.
Subacute Cutaneous Lupus Erythematosus (SCLE); is a nonscarring, non–atrophy-producing, photosensitive dermatosis. SCLE may also occur in Sjögren syndrome, associated with deficiency of the second component of complement (C2d) or it may be drug induced.
50% of all people with lupus experience sensitivity to sunlight and other sources of UV radiation.
The following to disorders are very similar but have very different outcomes:
Porphyria Cutanea Tarda (PCT)
This is the most common porphyria. It is caused by the accumulation of uroporphyrinogens, which cause a phototoxic skin reaction and liver abnormalities. PCT is due to low uroporphyrinogen decarboxylase activity. Spontaneous PCT can be caused by alcohol, hepatitis C or HIV infection, hemochromatosis or estrogen excess. Iron overload is a well-recognized trigger for PCT and thus something to be wary of in dialysis patients. The pathogenesis of this disorder in dialysis patients may also be due to the fact that they cannot excrete porphyrin precursors in the urine. The incidence of PCT in hemodialysis patients is between 1.2 – 18%. Clinically patients have fragile skin, blisters, vesicles and bullae in sun exposed in especially the dorsum of the hands. Sclerodermoid changes can occur in any skin area. Other clinical manifestations include hypertrichosis, hyperpigmentation, dark urine and pruritis. Histologically PCT is characterized by subepidermal separation of the skin with little or no inflammation. On IF, IgG and C3 can be seen along the dermoepidermal junction. Diagnosis in dialysis patients is by looking at the fractional levels of plasma porphyrin precursors. Treatment includes avoiding sun exposure and regular phlebotomy. Higher doses of ESA are usually required to avoid anemia. Chloroquine has also been used for this disorder but with varying results.
This disorder is also known as bullous dermatosis of ESRD. It has exactly the same clinical and histopathological changes as PCT (except there are no sclerodermoid changes or hypertrichosis in PP). However, there are no biochemical abnormalities of heme metabolism or porphyrins. This distinguishes it from PCT. One must be aware, however, that plasma uroporphyrin is increased at baseline in dialysis patients. Its incidence in dialysis patients is the same as for PCT. PP is associated with UV exposure, diuretics, NSAIDS (naproxen), antibiotics, antifungals (voriconazole), retinoids, finasteride, imatinib and others. In ESRD patients free-radical injury due to reduced glutathione levels in plasma and red blood cells is thought to play a role in PP. Treatment includes removal of any offending drugs and N-acetylcysteine. Symptoms may take months to improve.
Posted by Andrew Malone