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Patient Case: Amoebic Cutaneous Ulcer (Amoeba Cutis)

Patient Case: Amoebic Cutaneous Ulcer (Amoeba Cutis)

Discussion

Chief Complaint: “A large, painful wound on my abdomen is getting worse despite treatment.”

History of Present Illness:
A 52-year-old male construction worker presents with a progressively enlarging ulcer on his lower abdomen for the past three weeks. The wound initially started as a small, red, painful bump that gradually ulcerated and expanded despite local wound care and oral antibiotics. The patient reports recent travel to a tropical region, where he experienced a severe episode of diarrhea a few weeks before the ulcer appeared.

Past Medical History:

  • No known chronic illnesses
  • No diabetes or immunosuppressive conditions

Social History:

  • Works in construction, often exposed to contaminated water
  • No history of intravenous drug use

Physical Examination:

  • Skin: A large, necrotic ulcer with irregular borders on the lower abdomen, surrounded by erythema and mild tenderness. The base of the ulcer is covered with thick, purulent exudate.
  • Lymph nodes: Mild regional lymphadenopathy
  • Abdomen: Mild tenderness, no hepatosplenomegaly

Diagnosis:
The patient's history of travel, previous diarrhea, and a chronic non-healing ulcer raises suspicion for amoebic cutaneous ulcers (amoeba cutis), caused by Entamoeba histolytica, usually as a result of hematogenous spread or direct invasion from an intestinal infection.

Diagnostic Tests:

  • Ulcer biopsy and culture → Presence of trophozoites of E. histolytica
  • Stool analysis → E. histolytica cysts detected
  • Serology (ELISA or PCR) → Positive for E. histolytica antibodies

Management Plan:

  • Metronidazole (oral or IV) for systemic treatment of E. histolytica
  • Paromomycin to eliminate intestinal colonization
  • Wound care with debridement and antiseptic dressing
  • Avoidance of contaminated water sources

The patient is educated on proper hygiene and water sanitation to prevent recurrence. If left untreated, amoebic ulcers can progress to deep tissue destruction and secondary bacterial infections.

Questions
  1. What is the most likely causative organism of this patient’s cutaneous ulcer?
    a) Leishmania donovani
    b) Mycobacterium ulcerans
    c) Entamoeba histolytica
    d) Pseudomonas aeruginosa
  2. Which of the following is the most likely risk factor for developing amoebic cutaneous ulcers?
    a) Recent gastrointestinal infection with diarrhea
    b) Recent bite from a sandfly
    c) Exposure to stagnant freshwater lakes
    d) Contact with an infected animal
  3. What is the first-line treatment for this condition?
    a) Amphotericin B
    b) Metronidazole
    c) Doxycycline
    d) Rifampin
  4. Which diagnostic test is most useful in confirming the diagnosis of amoebic cutaneous ulcer?
    a) Skin biopsy with trophozoite detection
    b) Gram stain of wound exudate
    c) Acid-fast bacilli (AFB) test
    d) Blood culture for bacterial growth
Reveal answers

Answers

  1. (c) Entamoeba histolytica – This protozoan parasite is responsible for amoebic cutaneous ulcers, which usually develop due to direct invasion from an intestinal infection or hematogenous spread.
  2. (a) Recent gastrointestinal infection with diarrhea – The patient’s history of severe diarrhea before ulcer formation suggests that the amoeba first caused an intestinal infection (amoebiasis) before spreading to the skin.
  3. (b) Metronidazole – This antiprotozoal medication is the first-line treatment for amoebiasis, including both intestinal and extraintestinal forms such as cutaneous ulcers. It is often combined with paromomycin to eliminate intestinal colonization.
  4. (a) Skin biopsy with trophozoite detection – Identifying trophozoites of E. histolytica in ulcer biopsy samples confirms the diagnosis. Serology and stool tests may also help detect the presence of the parasite.