What are the infection-related dermatologic disorders associated with renal transplantation?

Updated: Mar 05, 2020
  • Author: Julia R Nunley, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

The iatrogenically induced decrease in cell-mediated immunity predisposes the renal transplant recipient (RTR) to infection by a variety of organisms. Timing and relative risk of the infections are determined by the degree of immunosuppression. Patients are at heightened risk for developing opportunistic infections during the first 6 months after transplantation because of the use of higher doses of immunosuppressive agents. Cutaneous examination is crucial in the surveillance for opportunistic infections, because cutaneous lesions frequently are the first sign of disseminated disease.

Mycobacterial infections

Later in the posttransplant period, patients may develop infections from a variety of acid-fast bacilli (AFB), specifically typical or atypical mycobacteria. [34, 35, 36] Although these infections are relatively unusual, they may cause significant morbidity. Multifocal disease is not uncommon. Organisms of the Mycobacterium fortuitum/chelonae complex are more common causes of AFB cutaneous infections, although others, such as M kansasii and M marinum, have also been reported. Histopathologic examination and tissue culture are necessary to make the correct diagnosis. Therapeutic options for these infections include antimicrobials, surgical debridement, and/or a reduction in immunosuppression.

Fungal infections

Fungal organisms are the most common cause of infection in the renal transplant recipient, occurring in 7-75%. [37] The wide variability in prevalence likely results from heterogeneity in diagnostic criteria, environmental exposures, geographic locations, and economic and hygienic factors.

Pityriasis versicolor has been shown to be the most common fungal infection and occurs in 18-48% of renal transplant recipients, which is a higher rate than found in the general population. Colonization of the upper back with Pityrosporum yeasts has been shown to occur 2-3 times more often in the renal transplant recipient relative to the general population. Pityrosporum organisms may predispose patients to increased incidence of folliculitis. Dermatophytosis, although common after renal transplantation, is no more common than in the general population.

Viral infections

Severe viral infections usually occur during the first year after transplantation and predominately result from herpes viruses. Cutaneous lesions resulting from infection with human papillomavirus (HPV) tend to develop later. Surveys suggest that the prevalence of HPV is 15-50% after the first year and increases to 77-95% by 5 years after transplantation.

Common and plane warts, which predominate, occur most frequently in sun-exposed areas and usually are multiple in number. HPV types 1, 2, 3, and 4 are found most commonly; however, many other HPV types have been reported in association with warty lesions in renal transplant recipients, including oncogenic types 16 and 18 and types 5 and 8, which usually are associated with epidermodysplasia verruciformis.

Eradication of these HPV infections is difficult, because the lesions respond poorly to therapy and recur frequently. Treating warts early and aggressively is best in the renal transplant recipient using routine modalities, such as cryotherapy, electrocoagulation, and carbon dioxide laser. Surgery and radiotherapy are not more effective and may result in scarring. Treatment with oral or topical retinoids may be an option for some patients.

Interferon alfa, which has been effective against warts in immunocompetent individuals, should not be used in the renal transplant recipient, because it may trigger allograft rejection. Imiquimod, an agent that can heighten the host's immune system by upregulating interferon, was initially thought to be similarly contraindicated in the transplant population. However, more recent studies have demonstrated it to be both effective and safe when used in a limited fashion.


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