Uncommon Infections Flashcards Preview

Dermatology Diploma > Uncommon Infections > Flashcards

Flashcards in Uncommon Infections Deck (50)
Loading flashcards...

What are the uncommon infections of the skin?

  • Parasites
  • Mycobacterium Diseases including Leprosy
  • HIV Infection


What are the 3 main types of parasites?

  • Arthropods
  • Worms
  • Protozoa


For what are the parasitical arthropods?

  • Lice
  • Ticks
  • Arachnids


For what are the parasitical worms?

  • Roundworms (Hookworms, pinworms)
  • Onchocerciasis
  • Schistosomiasis


What is this and what causes it?

Erythema Chronicum Migrans

It is caused by Borrelia Burgdorferi (A spriochete - type of bacteria)

It is transmitted by ticks.


Describe the different forms wereby Erythema Migrans can present.


What can happen if the Lyme's disease is undiagnosed or treated?

  • Neurological complications
  • Rarely
    • Arthritis
    • Cardiac Disease


What is a late manifestation of of Lyme's Disease?


Acrodermatitis chronica atrophicans (Scleroderma like rash)

It affects the distal parts of the body - due to chronic Borrelia Burgdorferi infection.



What is the investigation for lyme's disease?

What is interesting about this investigation?

Borrelia serology 

(it may take several months to be postive)



What would be the clinical picture if someone had skin disease due to worms?

  • Pruritus
  • Bloods - eosinophilia
  • History of foreign travel


For worms that affect the skin, how long can the incubation period be?

10 years



What is Onchocerciasis ("River Blindness) ?

How is it investigated and treated?

  • It is a parasitic worm (Ochocerca Volvulus) from central Africa and Southern America. It causes Pruritus with urticarial and papular rashes. It can then inhabit the eyes causing blindness (blue eyes).
  • Investigation: Skin snips
  • Treatment: Ivermectin


What is schistosomiasis?

How is it investigated and treated?

Schistosomiasis is a parasite called Schistosoma Mansoni. It is endemic in Africa, South America, India and the Far East.. It causes itchy skin, urticaria and eosinophilia. Skin lesions are most common on the trunk and can have a zosteriform appearance.


  • Investigations: stool ova/cysts/parasites may be seen on skin biopsy.
  • Treatment: Mebendazole


What is Leishmaniasis?

A Protozoa found in Africa, South America.

Initially crusts, then ulcers form and then they heal.

Treatment: Pentavalent Antimony


What are some other parasites of the skin?

  • Onchocerciasis - Central Africa and South America.
    • Itchy buttocks, lets, shoulders.
    • Diagnose with skin snips.
    • Treat with mebendazole.
  • Threadworms - treat with mebendazole
  • Larva currens - a larva that crawls under the skin leaves urticarial lines.
  • Larva migrans - dog/cat hookorm in faeces.


What are the two types of mycobacterium?

  • Atypical mycobacteria
  • Mycobacterium leprae


When should cutaneous TB be suspected?

If someone is coming form an endemic area with TB and has an unusual skin lesion.


What are the ways that TB manifests in the skin?

  • Lupus Vulgaris
  • Warty TB
  • Scrofuloderma
  • Tuberculides


What is this?

How does it present?


Lupus vulgaris

  • Due lymphatic/haematogenous spread from an underlying focus.
  • Affects normal skin especially head/neck/face.
    • Initially painless red-brown plaque with apple jelly.
    • Slowly enlarges & progressively destructive.
  • May be a plaque, a nodule or ulcerated.
  • Regional lymphadenopathy may be present.


What is this?

Warty TB

  • Presents due to re-infection in a sensitized patient usually from the far east.
  • Usually occurs on the hands and feet.


What is this?

What will skin biopsies show?


  • Due to breakdown of skin overlying focus of infection.
  • Usually over cervical lymph node - bluish red nodule or ulcer w fistulae.
  • Haematogenous spread.
  • Usually unwell with multiple bluish papules, vesicles or pustules.
  • Skin biopsy shows the presence of AFBs.


What are the 2 types of tuberclides?

  1. Papulonecrotic tuberclides
  2. Erythema induratum


What type of tuberuclide is this?

Papulonecrotic tuberculide

  • Cutaneous response to internal TB in a young person with good immunity.
  • Lesions usually contain bacilli (on PCR) but not cultured (Not AFB)
  • Recurrent symmetrical crops of non-itchy necrotising papules that heal with scarring.
  • Continue for months.
  • DDX is Pityriasis lichenoides acuta


What type of tuberculide is this?

How do you treat it?

Erythema induratum presents

  • Crops of small tender nodules on the lower legs.
  • Usually in TB patients with lung or cervical lymphadenitis.
  • Treat with standard anti-TB therapy.


Name the 3 atypical mycobacteria (non-TB & non-leprosy) that affect immunosuppressed individuals and sometimes healthy individuals?

  • Mycobacterium marinum aka fish tank/swimming pool granuloma.
    • Caused by water habitant especially stagnant warm water.
    • Causes nodule/pustule/ulcer on hand with sporotrichoid spread.
    • Heals spontaneously within a few months.
    • Treated with ciprofloxacin and clarithromycin.
  • Mycobacterium ulcerans - causes Buruli ulcer found in environment.
    • Ulceration down to fat.
    • Treatment with surgery antibiotics.
  • MAI complex - common in HIV skin lesions.
    • ​Nodules, pustules, ulcers, abscesses, panniculitis other organ systems may be involved.


What is leprosy?

  • Mycobacterium leprae which affects skin and peripheral nerves.
  • It is readily treatable with combined antibiotic therapy but the
  • immunological complications of leprosy frequently cause nerve damage even after effective antibiotic treatment. 


Where in the world is leprosy usualy found?

in the Tropics and Subtropics



How do we diagnose leprosy?

It is usually diagnosed when the following features are present:

  • Skin lesion typical of leprosy
  • Thickening of peripheral nerves
  • Acid fast bacilli in skin smear.


Describe the spectrum of Mycobacterium leprae infection

  • At one end is tuberculoid disease
    • A good cell mediated immunity.
    • Elimate the mycobacteria but can have granulomatous damage to their skin and peripheral nerves.
  • Other end - lepromatous disease
    • No cell mediated immunity.
    • Heavy load very much affecting nerves, skin, nasal mucosa.
  • In between these ends you have Borderline Leprosy.


Which end of the spectrum of leprosy is responsible for the spread of leprosy?

(Tuberculoid disease or Lepromatous disease)

Lepromatous disease