Topic Discussion: Pseudoporphyria

If a dialysis patient presents with a recurrent, sun-sensitive, bullous, and scarring rash on their hands, think of an entity called “pseudoporphyria”.

Patients with ESRD have a limited capability to excrete porphyrins. If there is history of recurrent PRBCS transfusions and/or liver disease, accumulation of iron pigments happens, which in turn provoke pseudoporphyria, characterized by a photosensitive, vesiculobullous skin eruption. Skin fragility and scarring are also observed.

See this reference

https://www.ncbi.nlm.nih.gov/pubmed?term=643142

https://www.ncbi.nlm.nih.gov/pubmed/10401031

Pseudoporphyria is clinically indistinguishable from porphyria cutanea tarda , and both conditions will be associated with elevated serum levels of porphyrins. In the case of pseudoporphyria, the elevated porphyrin levels result from lack of renal excretion. There is no enzyme problem here like in true porphyria cutanea tarda. 

In addition to dialysis, a wide range of drugs are associated with pseudoporphyria. It was first identified in patients taking quinolones. NSAIDS, retinoids, diuretics and some anti neoplastic agents such as TKIs have been associated with pseudoporphyria.

An entity to monitor in our ESRD patients.

Picture courtesy: From an article in JAMA on cyclosporine induced pseudoporphyria. 

Consult Rounds: Psoriasis and kidney disease

Psoriasis is an immune-mediated chronic inflammatory disorder of the skin. Association with kidney disease has been debated for a long time. Secondary renal amyloidosis in psoriatic arthropathy and drug-induced renal lesions secondary to methotrexate or cyclosporine are accepted accompaniments of

psoriasis. IgA nephropathy is also known to occur in psoriatic patients with HLA B27 genetic sharing. 

Are there GN that have been associated with psoriasis. One interesting report I found describes three findings: IgA, FSGS and membranous GN. All of them improved with treatment of the skin condition and ACEI/ARB therapy. The authors label the entity as  ‘‘psoriatic nephropathy’’ or ‘‘psoriatic kidney disease.’’ but with some doubt and a "?"

Other studies have looked at this association. Microalbuminuria has been studied as a potential link with psoriasis. In that one study, when abnormal urinary findings were compared to another cohort, patients with psoriasis had an increased prevalence of pathologic albuminuria compared with controls.  Of the eight patients with psoriasis who had urinary abnormalities, four underwent renal biopsy. Two of them had biopsy-proven glomerulonephritis: mesangial proliferative glomerulonephritis in one and IgA nephropathy in the other. Another study had looked at this connection.

But recently in JAMA dermatology, psoriasis was linked with many co morbid conditions including kidney disease. In a large cohort of over 9,000 patients, psoriasis overall was associated with higher prevalence of chronic pulmonary disease, diabetes mellitus, diabetes with systemic complications, mild liver disease , myocardial infarction,  peptic ulcer disease ,peripheral vascular disease , renal disease , and rheumatologic disease. Trend analysis revealed significant associations between psoriasis severity and each of the above comorbid diseases.  Potential confounding factors, such as hypertension, diabetes, and the use of nephrotoxic psoriasis treatments should be kept in mind when making this connection. A topic worth further studying.