A histopathological study of cutaneous leishmaniasis in Sri Lanka

Abstract

Introduction Cutaneous leishmaniasis is endemic in Sri Lanka. The immunopathogenesis of these lesions in Sri Lankans has not been documented. Objectives To classify skin lesions into histological groups, to assess parasitic load, density of each inflammatory cell type and necrosis and to characterise the lymphocytic reaction in cutaneous leishmaniasis in comparison to leprosy. Methods Skin biopsies from 31 patients with demonstrable amastigotes in smears or tissue sections were studied. The lesions were classified by two independent observers into four distinct histological groups based on different cell types in the inflammatory infiltrate and formation of granulomata. Parasitic load and the presence of necrosis were recorded. Immunohistochemical staining for CD45RO and CD20 for counting T and B cells respectively was done. Results Histological groups of cutaneous leishmaniasis ranging from group I-IV were similar to that of the spectrum in leprosy ranging from lepromatous to tuberculoid leprosy. The histological groups from I-IV showed a significant inverse relationship with the mean parasitic index. Necrosis was not a prominent feature. The mean percentage of T cells in the histological spectrum from group I-IV in leishmaniasis was similar to the spectrum from lepromatous to tuberculoid leprosy. Mean percentage of T cells were 20.1% in group I, 20.5% in group II, 33.8% in group III and 47.8% in group IV. Lepromatous, borderline tuberculoid and tuberculoid leprosy had 21.3%, 33.4% and 48.0% T cells respectively. Conclusion Cutaneous leishmaniasis is a spectral disease similar to leprosy. The mean percentage T cells from group I-IV were similar to those in the spectrum of leprosy and mean percentage B cells varied in a narrow range.

In situ immunopathological changes in cutaneous leishmaniasis due to Leishmania donovani

“…Its organization ranged from diffuse inflammatory infiltrate with parasitized macrophages to varying degrees of granuloma formation that extended from ill‐formed histiocytic to epithelioid granulomata. Similar histological changes have been observed in previous studies carried out on CL due to L. major and L. donovani in the local setting . Varying degrees of necrosis have been described in American tegumentary leishmaniasis as well as in CL in the old world .…”

“…Varying degrees of necrosis have been described in American tegumentary leishmaniasis as well as in CL in the old world . However, necrosis was not a prominent feature in this study, and therefore parasite elimination in CL due to L. donovani appears to depend on activation of macrophages to form epithelioid granulomas, rather than through a necrotizing process, as previously suggested . Interestingly, up‐regulation of IFN‐γ seen in this study provide further support for this assumption, as IFN‐γ is a potent activator of macrophages .…”

“…Forty‐six H and E‐stained sections were examined under a conference microscope (Olympus BX50, Tokyo, Japan) and categorized according to modified Ridley's criteria for leishmaniasis as previously described . These categories are defined and illustrated in Figures and .…”

“…Histopathological spectrum of CL in Sri Lanka has been described as similar to leprosy and grouped into four using a modified Ridley classification. It ranged from diffuse infiltrate of parasitized macrophages in group I to well‐formed epithelioid granulomata in group IV …”

Transepidermal elimination in cutaneous leishmaniasis: a multiregional study

“…The cutaneous reaction to leishmaniasis amastigotes has typically been classified into five groups and range from almost normal skin to an intense cellular infiltration, granuloma formation and necrosis; of these, necrosis has been considered the most effective means for elimination of amastigotes 51 . In addition, the presence of amastigotes in all epidermal layers suggesting transepidermal elimination has been shown in a limited number of cases in humans and animal models; however, these findings were not comprehensively evaluated 52–55 . In our series, cases with transepidermal elimination were thoroughly evaluated and were found to be associated with a decreased incidence of necrosis and ulceration, as well as a notably higher rate of interface changes.…”