Question
A 36-year-old traveler returns after several months living in remote jungle camps in South America. About 3 weeks later, he develops a persistent sore over the bridge of his nose that started as a small bump but has gradually enlarged into an ulcer despite antibiotic therapy. He also reports intermittent fever, fatigue, and unintentional weight loss. He recalls frequent exposure to vegetation but no obvious insect bites.
On examination, there is a chronic ulcerative lesion over the nasal bridge without nearby lymph node enlargement. Blood tests show mild anemia and raised inflammatory markers.
What is the most likely causative organism?
a. Histoplasma capsulatum
b. Leishmania braziliensis
c. Mycobacterium leprae
d. Actinomyces israelii
e. Candida albicans
Answer
Leishmania braziliensis
Detailed Explanation
This is a classic vignette of mucocutaneous leishmaniasis, caused by Leishmania braziliensis.
Why this is the correct diagnosis:
- Geography: Central/South America → strong clue for L. braziliensis
- Lesion evolution: papule → enlarging non-healing ulcer
- Location: nasal bridge → typical for mucocutaneous involvement
- Systemic symptoms: fever, malaise, weight loss
- Antibiotic failure: suggests non-bacterial cause
- Exposure: sandfly bites often unnoticed
Pathophysiology:
- Transmitted by sandflies
- Parasite invades macrophages
- Causes:
- Cutaneous lesions initially
- Later spread to mucosal tissues (nose, pharynx) → destructive lesions
Why other options are incorrect
a. Histoplasma capsulatum
- Endemic in Americas but causes pulmonary ± disseminated disease
- Skin lesions are secondary, not isolated nasal ulcers
c. Mycobacterium leprae
- Causes leprosy
- Features: hypopigmented anesthetic patches, nerve involvement
- Not acute ulcerative lesion
d. Actinomyces israelii
- Causes sinus tracts with sulfur granules
- Usually cervicofacial “lumpy jaw,” not isolated nasal ulcer
e. Candida albicans
- Causes superficial infections (oral, genital)
- Not chronic destructive ulcer of nasal bridge
Cheat Sheet for Exam
Leishmaniasis Types
| Type | Organism | Key Features |
|---|---|---|
| Cutaneous | L. tropica | Local ulcer at bite site |
| Mucocutaneous | L. braziliensis | Nose + mucosal destruction |
| Visceral (kala-azar) | L. donovani | Fever + splenomegaly + pancytopenia |
High-Yield Clues
- South/Central America + ulcer → think leishmania
- Nasal involvement → mucocutaneous type
- Starts as papule → ulcer
- No response to antibiotics
- Sandfly exposure often unnoticed
Flashcards
Q1: Which organism causes mucocutaneous leishmaniasis?
A: Leishmania braziliensis
Explanation: Causes destructive lesions of nose and mucosa.
Q2: What vector transmits leishmaniasis?
A: Sandfly
Explanation: Bite often unnoticed.
Q3: Key clinical progression of cutaneous leishmaniasis?
A: Papule → ulcer
Explanation: Gradual enlargement over weeks.
Q4: What is kala-azar?
A: Visceral leishmaniasis
Explanation: Caused by L. donovani, with splenomegaly and pancytopenia.
Q5: Why treat American cutaneous leishmaniasis aggressively?
A: Risk of mucocutaneous spread
Explanation: Especially with L. braziliensis.
MCQs
MCQ 1
A patient returns from Brazil with a chronic ulcer on the nose that began as a papule. What is the most likely organism?
a. Mycobacterium tuberculosis
b. Leishmania braziliensis
c. Nocardia asteroides
d. Sporothrix schenckii
Answer: b
Explanation: Nasal ulcer + South America → mucocutaneous leishmaniasis.
MCQ 2
Which of the following is FALSE about mucocutaneous leishmaniasis?
a. Transmitted by sandfly
b. Starts as papule
c. Always presents with lymphadenopathy
d. Can involve nasal mucosa
Answer: c
Explanation: Lymphadenopathy is often absent.
MCQ 3
A gardener develops nodules along lymphatics after thorn injury. Most likely organism?
a. Leishmania donovani
b. Sporothrix schenckii
c. Blastomyces dermatitidis
d. Mycobacterium leprae
Answer: b
Explanation: Sporotrichosis → nodular lymphangitis.
MCQ 4
Which feature best distinguishes leishmaniasis from bacterial infection?
a. Fever
b. Ulcer formation
c. Lack of response to antibiotics
d. Elevated CRP
Answer: c
Explanation: Key exam clue → antibiotics fail.
MCQ 5
Which organism causes visceral leishmaniasis?
a. Leishmania tropica
b. Leishmania mexicana
c. Leishmania donovani
d. Leishmania braziliensis
Answer: c
Explanation: Kala-azar = L. donovani.
MCQ 6
Which of the following is TRUE regarding Leishmania braziliensis?
a. Causes only pulmonary disease
b. Limited to Africa
c. Causes mucosal destruction of nose
d. Transmitted by mosquito
Answer: c
Explanation: Key feature = destructive mucocutaneous disease.
Summary for Quick Exam Revision
Mucocutaneous leishmaniasis, caused by Leishmania braziliensis, is a key tropical diagnosis seen in patients returning from Central or South America with chronic non-healing ulcers, especially involving the nasal region. The lesion typically begins as a papule and gradually ulcerates, often failing to respond to antibiotics. Transmission occurs via sandfly bites, which are frequently unnoticed. Systemic features such as fever and weight loss may accompany the condition. The distinguishing feature is its potential to spread from skin to mucosal surfaces, causing destructive lesions of the nose and pharynx. Diagnosis is usually made via biopsy, and treatment is necessary due to risk of progression. Differentials like sporotrichosis involve lymphatic spread, while blastomycosis and tuberculosis have different geographic and clinical patterns. Recognizing the combination of geography, lesion evolution, and antibiotic resistance is crucial for diagnosis.