Post kala azar dermal leishmaniasis in Adult
VL, or kala-azar (meaning "black fever" in Hindi), is a systemic protozoal disease that is caused by Leishmania donovani or Leishmania infantum. The majority of cases of VL are found in the following areas of the world: Eastern India, Nepal, Bangladesh, Ethiopia, Sudan, South Sudan, and Brazil. The disease is transmitted by the bite of an infected sandfly. The parasite exists in 2 forms: the amastigote form (in humans) and the promastigote form (in sandflies). The amastigote form is a round or oval structure that contains a nucleus and a DNA-containing body called the kinetoplast.
Geographic areas where PKDL is most prevalent are East Africa (especially Sudan) and South Asia (mainly Eastern India and Bangladesh). A subset of patients who receive treatment for VL go on to develop PKDL months or years after treatment. Interestingly, PKDL develops primarily in those cases of treated VL caused by L. donovani, not L. infantum.
There seems to be a variance in presentation in different areas of the world. In Sudan, the lesions generally appear within 6 months of treatment in approximately 50%-60% of cases of VL and last for a few months to about a year. In contrast, PKDL in India manifests later (1-2 years after treatment), may persist for much longer (even up to 20 years), and develops in only about 5%-10% of patients treated for VL.
The pathogenesis of the disease is not clear, and why only a subset of patients develop PKDL is not known. Studies have shown that this is an immune-mediated process. Certain risk factors associated with the development of PKDL are suboptimal treatment of VL, young age, HIV infection, and antiretroviral treatment.
B55.0 – Visceral leishmaniasis
67896006 – Post-kala-azar dermal leishmaniasis
Differential Diagnosis & Pitfalls
- Leprosy – These diseases can be distinguished clinically because leprosy is associated with anesthetic lesions, while PKDL is not.
- Vitiligo – In vitiligo, the lesions are depigmented versus the hypopigmented or erythematous lesions seen in PKDL.
- Measles – In measles, there are other systemic features such as fever, malaise, and fatigue. Koplik spots are seen in measles, which helps differentiate it from PKDL.
- Some other dermatological conditions that may mimic PKDL are pityriasis versicolor (tinea versicolor) and pityriasis alba. History of prior VL and skin biopsy may be needed to differentiate these conditions from PKDL.