Zheng Qi   2021-03-17

Core Clinical Traits of Cutaneous Leishmaniasis (CL)

CL is the most widespread form of leishmaniasis, with an extremely broad clinical spectrum that varies significantly across endemic regions, shaped by factors including the infecting Leishmania species, the host’s immune status, and the local zoonotic transmission cycle. The classic lesion begins as a small, painless papule or nodule at the exact site of the infected sandfly bite, which slowly enlarges over weeks to months to form a well-defined painless ulcer with firm surrounding induration. Different parasite strains produce distinct ulcer morphologies: strains circulating in China typically form "volcano crater" ulcers with raised, thickened edges and a sunken central depression, while Latin American strains often cause flat, shallow "pizza-like" ulcers without prominent raised borders. Some lesions may heal spontaneously over months or years without treatment, leaving permanent, disfiguring scars with abnormal pigmentation, while others persist and progress to more severe variants such as diffuse cutaneous leishmaniasis, which presents as widespread non-ulcerative thickened plaques and nodules across the face and limbs that closely resemble lepromatous leprosy and rarely resolve on their own.

Key Features of Mucocutaneous Leishmaniasis (MCL)

MCL, also known as espundia, is almost exclusively caused by Leishmania braziliensis complex parasites, and most cases develop months to decades after the initial primary CL lesion has fully healed. A small subset of patients present with mucosal damage without any prior history of visible skin lesions, making early diagnosis extremely challenging. The disease progressively invades and destroys the soft tissues and cartilage of the nasal, oral and pharyngeal mucous membranes, leading to characteristic facial swelling that forms the classic "tapir nose" deformity. Unlike CL lesions, MCL lesions never heal spontaneously, and advanced cases often trigger severe secondary bacterial infections that can cause fatal complications such as bronchopneumonia and severe malnutrition.

Diagnostic Challenges

Both CL and MCL lesions lack pathognomonic features, leading to frequent misdiagnosis in low-resource endemic settings. CL ulcers are easily mistaken for cutaneous tuberculosis, deep fungal infections, impetigo, psoriasis, tropical ulcers, venous leg ulcers, warts and herpes zoster, while early MCL lesions are often misidentified as common inflammatory nasal conditions before irreversible tissue damage occurs. This non-specific presentation is one of the core reasons leishmaniasis remains a severely underdiagnosed neglected tropical disease across most endemic regions.

Edited by: Secretariat of the Asia-Pacific Network for Drug and Diagnostics Innovation
Produced by: Zheng Qi
Reviewed by: Zhang Haobing
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