Microbiology- chapter 17

Describe a Lesion

Any general observable abnormality in the skin.

Describe primary lesion.

They are directly associated with a disease and are considered the key features of identifying various infections.

Describe secondary lesions.

Less strictly defined and have diverse origins.

PRIMARY LESION: vesicular rash

small elevated region filled with clear fluid.

“vesicular clear”

PRIMARY LESION: Bulla (plural bullae)

Think of the various sizes a blister can become.

A bulla is a vesicle more than 0.5 cm diameter

“Bulla is a blister”

PRIMARY LESION: Maculla

Think of a freckles.

Maculla are flat discolored areas of the skin.

“makeup covers macula”

PRIMARY LESION: Papule (papule rash)

Think of a wart.

Non-fluid filled lesions. They are less than .5 cm diameter.

PRIMARY LESION: Pustule

Think pimples filled with pus.

Raised lesion filled with pus below the surface.

Ex) Inflammatory acne filled with pus.

PRIMARY LESION: Cyst

Is a closed fluid filled sac, deeper in the skin, typically painless, until infected or ruptured.

Think: nodular cystic acne

PRIMARY LESION: Maculopapular rash

Small slightly raised papule lesions that overlay macules

ex) rubella and rubeola

SECONDARY LESION: Crust

Dried plasma or exudate on the skin, having a honey colored appearance.

Ex) Staphylococcal impetigo

SECONDARY LESION: Scale

Think psoriasis dry fish scale skin

Outer epidermal layers flaking off of lower skin layers as a result of tissue damage or infection.

SECONDARY LESION: Purpura

Think PURPLE

A rash of large purple spots that evolve from bleeding in the subcutaneous skin layer.

ex) Bloodstream infections (septicemia/bacteremia); meningococcal meningitis; also seen in many noninfectious scenarios

SECONDARY LESION: Petechiae

Similar to purpura, petechiae are pinpoint spots that are from broken capillaries.

ex) Congenital cytomegalovirus infection, scarlet fever, bacterial endocarditis, excessive strain from vomiting or coughing or childbirth; drug reactions

SECONDARY LESION: Ulcer

A sore irregular shape that results as epidermal and dermal skin layers are destroyed.