Cutaneous Leishmaniasis

Abstract

The ulcerated papules of cutaneous leishmaniasis represent an unusual form of granulomatous dermatitis caused by Leishmania species, a protozoan transmitted by sandfly bites. As the disease is not native to North America, clinical suspicion is partially based on a compatible travel history and may result in a biopsy. The key role of standard morphology is the identification of Leishmania organisms, supplemented by Giemsa and/or CD1a immunostaining. Histologically, the organism may be confused with Histoplasma species, which is resolved by staining with methenamine silver or PAS. Four cases of cutaneous leishmaniasis are presented for which organisms were present in 3; polymerase chain reaction and DNA sequencing for speciation done by the Center for Disease Control and Prevention (CDC) was confirmatory in 3 cases, including the one case without histologically identifiable organisms. Rare unexplained cases of cutaneous leishmaniasis without a travel history have been reported outside endemic areas. The present cases emphasize the importance of diagnostic awareness of unusual infections such as this in the context of political unrest, ease of international travel, climate change and the possible expansion of geographic vector distribution. In the morphologic absence of organisms, the diagnosis may require molecular techniques, currently available on a referral basis to pathologists without charge from CDC.

The EP3662 clone of CD1a supports the diagnosis of New World cutaneous leishmaniasis

“…Cutaneous leishmaniasis (CL) is one of the three clinical forms of the disease and may present with nodules or plaques that frequently ulcerate. 1,2 On histopathology, 1-to 3-μm rounded amastigotes are identified within enlarged histiocytes. In New World leishmaniasis, a "marquee sign," in which organisms line up around histiocyte borders, may be observed.…”

“…3 Giemsa stain has historically been used to aid in the identification of Leishmania, but provides limited diagnostic utility in routine practice. 1,2 Polymerase chain reaction (PCR) is the gold-standard diagnostic tool for leishmaniasis but is not available in every country in which the parasite is endemic.Recently, CD1a immunostain has been used to identify amastigotes, demonstrating a peripheral "membrane-like" pattern with accentuation in one of the poles, leaving the unstained nucleus in the center. [1][2][3][4][5] The MTB1 clone was shown to be sensitive for the detection of Old World leishmaniasis but was variably sensitive for New World disease.…”

“…1,2 Polymerase chain reaction (PCR) is the gold-standard diagnostic tool for leishmaniasis but is not available in every country in which the parasite is endemic.Recently, CD1a immunostain has been used to identify amastigotes, demonstrating a peripheral "membrane-like" pattern with accentuation in one of the poles, leaving the unstained nucleus in the center. [1][2][3][4][5] The MTB1 clone was shown to be sensitive for the detection of Old World leishmaniasis but was variably sensitive for New World disease. [1][2][3][4] DeCoste et al demonstrated the use of EP3662 in a single case of Old World CL caused by Leishmania infantum with abundant amastigotes.…”

“…[1][2][3][4][5] The MTB1 clone was shown to be sensitive for the detection of Old World leishmaniasis but was variably sensitive for New World disease. [1][2][3][4] DeCoste et al demonstrated the use of EP3662 in a single case of Old World CL caused by Leishmania infantum with abundant amastigotes. 6 We sought to determine the sensitivity of the EP3662 clone in detecting New World CL.…”

“…3 Giemsa stain has historically been used to aid in the identification of Leishmania, but provides limited diagnostic utility in routine practice. 1,2 Polymerase chain reaction (PCR) is the gold-standard diagnostic tool for leishmaniasis but is not available in every country in which the parasite is endemic.…”