A trespasser from a foreign land? A case report of primary mucosal leishmaniasis - BMC Infectious Diseases - BMC Infectious Diseases

This case represents a clinically and laboratory diagnostic challenge. Since the patient resides in an area of Israel endemic for CL, we expected the causative agent to be either L. tropica or L. major. While L. infantum has been reported to cause ML in other regions of the Mediterranean basin, leishmaniasis caused by L. donovani is rare in Israel and primarily found in East African refugees with HIV-VL co-infections. Therefore, although described, it was surprising for us to identify the parasites causing ML as L. donovani 4 years following a stay in central and North Africa with no evidence or report of former skin lesions. The fact that visceralizing Leishmania can produce mucosal disease, raises the question whether the lesions observed in this patient represent the primary site of parasite inoculation (as this patient is reported to breath orally during sleep), or a secondary localization following current or former VL, especially in the presence of an enlarged spleen. The absence of other clinical manifestations of VL including fever, pancytopenia and enlarged liver, as well as the lack of a serological response, do not support concurrent VL. It is worth noting that serology with an rK39-based immunochromatographic test may provide supportive evidence for a diagnosis of VL (specifity 91%), but it is not recommended as a stand-alone VL diagnostic test; however, it may be useful to direct more invasive testing [1]. The rK39-test sensitivity for diagnosing VL in populations unlikely to have HIV/AIDS is considered high (94%) [1], and lowers the likelihood of VL in the present case. Nevertheless, the cumulative dose of liposomal amphotericin B given to the patient (30 mg/kg) was also compatible with the recommended dose for treating VL (21 mg/kg if immunocompetent) [1], and other etiologies causing enlarged spleen should be further searched following repeated ultrasonography.

The dense infiltrate of inflammatory cells with abundant Leismania organisms found in histopathological sections in this case are not typical to ML. The key features of ML are delayed type hypersensitivity manifesting as abundant granulomas and low number of parasites in the lesions, mediated by an exaggerated Th1 response with elevated IFN-γ and TNF-α production and lower IL-10 [8]. Interestingly, Leishmania RNA Virus 1 (LRV1) harbored by L. brazilensis and L. guyanensis was found to induce proinflammatory cytokines and chemokines that contribute to autophagy, tissue destruction and disease exacerbation in ML [9]. It is possible that Old world Leishmania species that cause ML, trigger a different immune response that led to abundant parasites in lesions and diminished formation of granulomas, or that a genetic driven local or systemic immunosuppression in this patient resulted in atypical immunopathology [10].

In conclusion, we present a case of L. donovani ML in an Israeli resident with a former travel to central and North Africa, with no documented or prior cutaneous lesions. A possible explanation for the mucosal presentation could have been former asymptomatic or subclinical VL with hematogenous dissemination to mucosal membranes, but this hypothesis was not supported by the sensitive rk39 dipstick test. Therefore, though uncommon, ML in this patient probably presents the only manifestation of L. donovani infection. A delay in diagnosis and treatment, such as in this case, have led to progression of the maxillary gingival lesions towards the hard palatal and the soft palate, and could have potentially compromised the upper airway. This underscores the importance of early searching for the presence of Leishmania in patients with suspected neoplasia or autoimmune disease of the upper airway or oral cavity, if they have resided in Leishmania endemic zones. Laboratory processing and molecular workup are necessary to appropriately characterize and treat the disease.

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