Pimples and Boils!! Dr Nathan Harvey Anatomical Pathology, PathWest
Overview & Learning Objectives Review the cardinal signs/symptoms of acute inflammation Review the histological features of acute inflammation Overview of the possible outcomes of acute inflammation Understand the clinical signs/symptoms, pathological mechanisms and histological features of common acute inflammatory disorders of the skin: Impetigo Acne vulgaris Folliculitis Furuncle Erysipelas/cellulitis
Neutrophils
What is Pus? A protein-rich fluid produced as a product of inflammation It comprises: Leukocytes (white blood cells) Debris from dead cells Tissue elements which have been liquified by the action of neutrophil enzymes Bacteria that cause pus formation are called suppurative, pyogenic or purulent
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Microscopic Structure of the Skin Stratum Corneum
Hair follicle Epidermis Dermis Arrector pili muscle Eccrine sweat gland Subcutaneous adipose tissue
Papillary dermis Hair follicle (note the solar elastosis : not technically normal, but almost ubiquitous in WA!) Sebaceous gland Reticular dermis Arrector pili muscle Blood vessels Eccrine sweat gland
Cornified layer (stratum corneum) Granular layer (stratum granulosum) Prickle layer (stratum spinosum) Basal layer (stratum basalis) Melanin pigment Melanocyte Solar elastosis
Cutaneous Bacterial Infections Pyogenic infections Staphylococcus aureus Streptococcus Corynebacteria Neisseria Mycobacteria Chlamydia Rickettsia
Impetigo Acute superficial infection of the skin Most common bacterial skin infection of childhood Adults can also be affected Athletes Military Institutions Predisposing factors Minor trauma Poor hygiene Warm, humid climate
Impetigo Organism is often Staphylococcus aureus (esp in bullous subtype) Also Streptococcus, anaerobes Staphylococcus aureus may produce exfoliative toxins
Common Impetigo School sores Impetigo Thin walled vesicles or pustules Rupture to form a thick golden crust Solitary or clustered, face or extremities Bullous Impetigo Erosions and flaccid bullae Caused by an exotoxin which results in keratinocytes falling apart and blister formation
Histopathology Subcorneal (ie under the stratum corneum) collection of neutrophils Can see more neutrophils migrating upwards through the epidermis Surface crust of serum and dying neutrophils May see bacterial colonies
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Staphylococcal Scalded Skin Syndrome Another blistering disorder caused by Staphylococcus aureus, but with a different mechanism Occurs in infants Widespread blisters that rupture easily No bacteria in the blisters Caused by an endotoxin that is made by the bacteria elsewhere and is transported via the bloodstream
Acne Vulgaris Pimples! An inflammatory disorder of the pilosebaceous unit ie the hair follicle and attached sebaceous gland Common Affects a large proportion of teenagers Usually improves spontaneously after adolescence
Clinical Appearances The lesions that make up acne are variable and include: Comedones Papules Pustules Cysts Sinuses Scars
Clinical Appearances Comedones are widened hair follicles which are filled with keratin, other debris, bacteria and sebum Closed : whiteheads Open: blackheads
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Scars Inflamed papule Open comedones www.derm101.com
Pathogenesis Four inter-related factors Abnormal follicular keratinisation, with retention of keratin within the follicle This process is the precursor to comedone formation May be aided by a bacterial biofilm Increased sebum production Androgens Presence of bacteria: Propionibacterium acnes Inflammation
Pathogenesis Ongoing dilation of comedo leads to the wall of the follicle becoming very thin Eventually it ruptures The keratin, sebum and bacteria incite an acute inflammatory response Predominantly neutrophils at first pustule formation Followed by granulomatous inflammation and fibrosis (scarring) The acute inflammatory focus can enlarge into an abscess. Sinus tracts result when the epidermis grows down in an attempt to wall off the inflammation
Neutrophils Plugged and dilated follicle
Superficial Folliculitis Typically affects the superficial part of the hair follicle, called the infundibulum Thus, perhaps more correctly should be called infundibulitis May be related to bacterial infection (eg Staphylococcus aureus) Neutrophils under the statum corneum and around the infundibulum pseudofolliculitis is a term used to describe a foreign body response to hair shafts that have ruptured out of the follicle into the surrounding dermis
www.derm101.com Small pustules around hair follicles
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Furuncle Boils A deeper infectious inflammatory process centred on the pilosebaceous unit Typical locations include the back of the neck, buttocks and thighs Sites of friction with clothing Begins as a painful papule with surrounding erythema (redness) and swelling The centre becomes soft, yellow and may discharge pus A carbuncle is a coalescence of several furuncles
Histological features A deep dermal abscess (ie neutrophils again!) centred around a hair follicle The follicle may be destroyed although residual hair shafts may be seen The surrounding inflammation may extend into the deeper tissues The surface oftens shows a crust of serum and dying neutrophils
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Acute inflammation (ie neutrophils) in the deeper parts of the follicle
Furuncle - Causes Often bacterial, usually Staphyloccocus aureus Pseudomonas aeruginosa is associated with hot tub folliculitis Develops 8-48 hours after recreational exposure to the organisms, which is found in contaminated spas Viral eg herpes simplex Fungal
Erysipelas/Cellulitis Erysipelas is an acute inflammatory process within the dermis which is usually caused by Streptococcus pyogenes Oedematous, tender, hot, well demarcated red plaques Often accompanied by a fever Face, feet, hands and lower limbs are most affected
Erysipelas/Cellulitis Cellulitis is a similar processs which involves slightly deeper tissues More often occurs on the legs Expanding area of erythema S pyogenes is again usually the causative organism
Predisposing Factors Minor trauma Peripheral vascular disease Diabetes Lymphoedema Alcohol abuse
Histology Dermal oedema and lymphatic dilatation Diffuse infiltrate of neutrophils
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Summary Remember: the cardinal signs & symptoms of acute inflammation The histological features The possible sequelae By applying the above to different anatomical components of the skin: Impetigo Acne vulgaris Folliculitis Furuncle Erysipelas/cellulitis