Cutaneous Manifestations of Infections

Question 1

Direct changes to skin example

Answer 1

-Cellulitis
=replication of bacteria in the skin and soft tissues= swelling and redness of the leg

Question 2

Indirect changes to skin example

Answer 2

-Infective endocarditis
=immune complexes deposited in skin= form Osler’s nodes

Question 3

Local changes to skin example

Answer 3

-Shingles
=small patch of a single dermatome has erupted with a reactivation of varicella zoster virus

Question 4

Systemic changes to skin example

Answer 4

-Scarlet fever
=widespread immune mediated reaction to infection by a Streptococcus pyogenes (a betahaemolytic, Lancefield antigen group A streptococcus)

Question 5

Factors to consider in taking a history of skin changes

Answer 5

-Timing
=when first appeared/new and acute
-Distribution
=dermatomal (shingles)/ sun-exposed (photosensitive rash)/ sweaty areas (fungal)
-Evolution
=changes over time/ multiple stages in time visible at once
-Associated symptoms
=systemic features (fever/weight loss/tiredness), local (Koplik’s spots, regional pain)
-Exacerbating/ relieving factors
=sunlight, creams/lotions (steroid)

Question 6

Background in taking a history of skin changes

Answer 6

-Personal Contacts
=Unwell contacts or contacts with rashes
=Contacts with children
=Sexual contacts
=Pregnant women

-Exposures
=Chemical
=Medical
=Travel

-Vaccination/prior history
=Measles vaccinations
=Prior VZV infection

Question 7

Factors to consider when describing cutaneous lesions

Answer 7

-Is it single or multiple?
-Is it flat or raised or both?
-Is it well defined or diffuse?
-What colour is it?
-What size is it?
-How is it distributed?
-Does it blanche?
-If it is raised: is it filled with tissue, serous fluid or pus?

Question 8

Stages of chicken pox rash

Answer 8

1. Erythematous macule
2. Papule
3. Blisters to form vesicle
4. Serous fluid becomes pus: pustule
5. Skin breaks: ulcer

Question 9

Describe the chicken pox cutaneous lesion

Answer 9

-Many lesions
-Discrete
-Erythematous
-C.5mm
-Blanching
-Mainly raised
-Mainly serous vesicles
-Over the whole body

Question 10

Describe a Lyme disease lesion

Answer 10

-Single, well defined, slightly raised, area of erythema (patch)
-Redness not uniform: bullseye rash of erythema (chronicum) migrans

Question 11

Describe Meningococcal rash

Answer 11

-Widespread, non-blanching, erythematous papular rash
-C.1cm discrete papules
-High fever

Question 12

Describe meningitis

Answer 12

-Caused by bacteraemia with Neisseria menigitidis
-Pathology: small vessel vasculitis caused by the immune response to septicaemia
-Present in c. 40% of cases: the absence doesn’t exclude infection with N. meningitidis
-Anyone (esp. child) attending with signs of sepsis and a nonblanching rash requires urgent assessment: rash may be prodrome of critical illness

Question 13

Examples of arboviruses

Answer 13

-Dengue virus: blanching rash leaves a handprint behind when pressed
-Zika virus: blanching maculopapular rash: not clinically distinguishable from dengue or chikungunya

Question 14

Non-infectious rashes

Answer 14

-Morbilliform (measles-like) reaction to penicillin
=blanching maculopapular rash

-Still’s disease
=salmon pink blanching maculopapular rash on torso caused by autoimmune disease and often associated with a fever and lymphadenopathy