Skin infestations and infections 2 Flashcards Preview

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Flashcards in Skin infestations and infections 2 Deck (54)
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1
Q

What is the initial presentation of necrotising fasciitis?

A

dusky induration (usually of a limb), followed by rapid painful necrosis of skin, connective tissue and muscle

2
Q

What is necrotising fasciitis caused by?

A
  • Potentially fatal

* Usually synergistic: streptococci, staphylococci, enterobacteriaceae and anaerobes

3
Q

What is in the diagnosis and treatment of necrotising fasciitis?

A
  1. Prompt diagnosis essential (requires high index of suspicion), followed by broad-spectrum parenteral antibiotics and surgical debridement
  2. MRI can aid diagnosis.
  3. Blood and tissue cultures can determine organisms and sensitivities.
  4. Mortality is high.
4
Q

What is it called when necrotising fasciitis affects the scrotum?

A

Fournier’s gangrene

5
Q

What is atypical mycobacterial infection?

A

Important cause of infection in immunosuppressed states

6
Q

What do mycobacterium marinum cause?

A
  • indolent granulomatous ulcers (fish-tank granuloma) in healthy people
  • Sporotrichoid spread
7
Q

What does myobacterium choelonae and abscessus come from?

A

puncture wounds, tattoos, skin trauma or surgery

8
Q

What does myobacterium ulcerans cause?

A

limb ulceration in Africa (Buruli ulcer) or Australia (Searle’s ulcer)

9
Q

Where does annular erythema develop (borreliosis lyme disease)?

A

at site of the bite of a Borrelia-infected tick

10
Q

What does the bite form in lyme disease?

A

Ixodes tick infected with Borrelia burgdorferi

11
Q

What are the intial cutaneous manifestations in lyme disease?

A
  1. Erythema migrans (only in 75%)
  2. Erythematous papule at the bite site
  3. Progression to annular erythema of >20cm
12
Q

What are the other manifestations of lyme disease?

A
  1. 1-30 days after infection, fever, headache
  2. Multiple secondary lesions develop - similar but smaller to initial lesion
  3. Neuroborreliosis
  4. Arthritis – painful and swollen large joints (knee is the most affected join)
  5. Carditis
13
Q

What happens in neuroborreliosis?

A
  1. Facial palsy / other CN palsies
  2. Aseptic meningitis
  3. Polyradiculitis
14
Q

What is the serology and histopathology like in lyme disease?

A
  • Serology not sensitive
  • Histopathology - non-specific
  • High index of suspicion required for diagnosis
15
Q

What is tularaemia caused by?

A

Francisella tularensis

16
Q

What is tularaemia aquired through?

A
  1. Handling infected animals (squirrels and rabbits)
  2. Tick bites
  3. Deerfly bites
17
Q

What is the form of tularaemia?

A

Ulceroglandular form

18
Q

What are the symptoms of tularaemia?

A
  • Primary skin lesion is small papules at inoculation site that rapidly necroses – leading to painful ulceration
  • +/- local cellulitis
  • Painful regional lymphadenopathy
19
Q

What are systemic symptoms of tularaemia?

A

fever, chills, headache and malaise

20
Q

What is another word for ecthyma gangrenosum?

A

Pseudomonas aeruginosa

21
Q

When does ecthyma gangrenosum occur?

A

neutropaenic patients

22
Q

What does ecthyma gangrenosum look like?

A
  1. Red macule(s) to oedematous to haemorrhagic bullae.

2. May ulcerate in late stages or form an eschar surrounded by erythema

23
Q

When organisms can cause a similar appearance to escharotic lesions?

A
  • Pseudomonas
  • Aspergillosis
  • Leishmaniasis
  • Cryptococcosis
  • Lues maligna
  • Rickettsial infections
  • Cutaneous anthrax
  • Tularaemia
  • Necrotic arachnidism (brown recluse spider bite)
  • Scrub typhus (Orientia tsutsugamushi)
  • Rat bite fever (Spirillum minus)
  • Staphylococcal or streptococcal
  • Ecthyma
  • Lyme disease
24
Q

What is another name for syphilis?

A

Treponema pallidum

25
Q

What is the primary infection chancre in syphilis?

A

painless ulcer with a firm indurated border

26
Q

What happens one week after the primary chancre in syphilis?

A
  1. Painless regional lymphadenopathy one week after the primary chancre
  2. Chancre appears within 10-90 days
27
Q

When does secondary syphilis begin?

A

50 days after chancre

28
Q

What are the symptoms of secondary syphilis?

A

Malaise, fever, headache, pruritus, loss of appetite, iritis

29
Q

Why is syphilis a great mimicker?

A
– low threshold for testing
 - Rash (88-100%) -Pityriasis rosea-like rash
 - Alopecia (‘moth-eaten’)
 - Mucous patches
 - Lymphadenopathy 
 - Residual primary chancre 
 - Condylomata lata 
 - Hepatosplenomegaly
30
Q

What is lues maligna?

A

Rare manifestation of secondary syphilis

31
Q

What happens in lues maligna?

A

Pleomorphic skin lesions with pustules, nodules and ulcers with necrotising vasculitis

32
Q

When is lues maligna more frequent?

A

HIV manifestation

33
Q

What happens in tertiary syphilis?

A
  1. Gumma Skin lesions - nodules and plaques
  2. Extend peripherally while central areas heal with scarring and atrophy
  3. Mucosal lesions extend to and destroy the nasal cartilage
  4. Cardiovascular disease
  5. Neurosyphilis (general paresis or tabes dorsalis)
34
Q

What is involved in the diagnosis of syphilis?

A
  • Clinical findings
  • Serology
  • Strong index of suspicion required in 2ndary syphilis
35
Q

What is the treatment of syphilis?

A

IM benzylpenicillin or oral tetracycline

36
Q

What is the name for leprosy?

A

Mycobacterium leprae

37
Q

What does leprosy affect?

A
  • Obligate intracellular bacteria -predominantly affects skin & nerves, but can affect any organ
  • Clinical spectrum
38
Q

What happens in lepromatous leprosy?

A
  1. Multiple lesions: macules, papules, nodules

2. Sensation and sweating normal (early on)

39
Q

What happens in tuberculoid leprosy?

A
  1. Solitary or few: elevated borders – atrophic center, sometimes annular
  2. Hairless, anhidrotic, numb
40
Q

What can TB affect?

A
  • any organ system, including the skin

- 5-10% of infections lead to clinical disease

41
Q

How can cutaneous TB be acquired?

A
  1. Exogenously (primary-inoculation TB and tuberculosis verrucosa cutis)
  2. Contiguous endogenous spread – (scrofuloderma )or autoinoculation – periorificial tuberculosis
  3. Haematogenous/lymphatic endogenous spread –dissemination (lupus vulgaris, miliary
    tuberculosis, gummas
42
Q

What are the investigations for TB?

A
  1. Interferon-γ release assay (Quantiferon-TB)
  2. Histology – ZN stain
  3. Culture / PCR
43
Q

What are the cutaneous manifestations of TB?

A
  1. Tuberculous chancre
  2. Tuberculosis verrucosa cutis
  3. Scrofuloderma
  4. Orificial TB
  5. Lupus vulgaris
  6. Miliary TB -
  7. Tuberculous gumma
44
Q

What is TB chancre?

A

painless, firm, reddish-brown papulonodule that forms an ulcer

45
Q

What is TB verrucosa cutis?

A

wart-like papule that evolves to form redbrown plaque

46
Q

What is scrofuloderma?

A

subcutaneous nodule with necrotic material - becomes fluctuant and drains, with ulceration and sinus tract formation

47
Q

What is orificial TB?

A

non-healing ulcer of the nasal mucosa that is painful

48
Q

What us lupus vulgaris?

A

red brown plaque - +/- central scarring, ulceration

49
Q

What is milary TB?

A

pinhead-sized, bluish-red papules capped by minute vesicles

50
Q

What is TB gumma?

A

firm subcutaneous nodule - later ulcerates

51
Q

What is molluscum contagiosum?

A

Poxvirus infection

52
Q

When is molluscum contagiosum common?

A

children and immunocompromised

53
Q

What are the differential diagnosis of molluscum contagiosum?

A
  1. Verrucae
  2. Condyloma acuminata
  3. Basal cell carcinoma
  4. Pyogenic granuloma
54
Q

What are the treatment options for molluscum contagiosum?

A
●Usually resolve spontaneously 
●Treatment options
-curettage
-imiquimod
-cidofovir