Skin Histology, Function & Lesions

Skin Histology

• Skin is composed of 3 layers: Epidermis, Dermis, and Subcutaneous fat
• Other parts include hair shaft, sweat gland, sebaceous gland, arrector pili muscle, hair bulb and dermal papilla

Skin Function

• Aspect to the world
• Holds the structures together
• Prevents water loss
• Defends against environment
• Temperature control
• Barrier against micro-organisms
• Skin sensations
• Disease occurs when there is impairment of the normal function or structure

Skin Patient - Important Considerations

• When examining skin patients, take history and ensure standard approach
• Examination involves: inspection (lesional and whole skin), nails and har, palpation, regional LN (lymph node)
• Four aspects of looking at lesions are: morphology, shape, distribution and color

Primary Lesions

• Macule or patch; flat lesions- macule is <1cm whereas patch is >1cm
• Papule or nodule; skin lesion
• Vesicle or Bulla; skin lesion
• Wheal is the primary lesion of urticaria
• Burrow is the primary lesion of scabies and a linear elevation of the epidermis
• Plaque describes changes in texture and can be elevated or depressed
  • Originates de novo or results from confluence of multiple papules, has a large surface area compared to its height

Secondary Lesions

• Include crust, furrow, pustule, excoriation, abrasion, erosion, fissure, ulcer

Morphology: Macule

• Described as circumscribed color change with no elevation or depression in any shape, and <1 cm in size

Morphology: Patch

• Patch has circumscribed color change with no elevation or depression in any shape, and >1 cm in size

Morphology: Papule

• This is a solid elevated lesion, flat pointed or rounded and less than 0.5cm
• Can coalesce into plaque

Morphology: Nodule

• Described as circumscribed solid elevation that is epidermal, dermal or SC
• Variable shaped measuring greater than 0.5cm in size

Morphology: Plaque

• Characterised as having a circumscribed solid elevation that is usually flat-topped, with surface area greater than height
• Measures greater than 1cm

Morphology: Vesicle

• A circumscribed, fluid-filled elevated lesion that measures less than 0.5cm

Morphology: Bulla

• A circumscribed, fluid-filled elevated lesion that measures greater than 0.5cm

Morphology: Wheal

• Characterized by edematous elevation that is itchy, variable in size and evanescent
• Diagnostic of urticaria

Morphology: Pustule

• Described as having either a vesicle or bulla containing pus
• Cream, yellow or green in color; and may or may not be sterile
• Varies in size and shape

Morphology: Scales

• Laminated masses of keratin, dry or greasy.
• Overly macule, papule or plaque

Morphology: Crusts

• Collection of debris on the the skins surface that is a dried exudate of serum, pus, or blood, also described as a scab

Morphology: Erosions

• Focal loss of epidermis with partial or total thickness, doesn’t penetrate into the dermis
• Heals without scarring

Morphology: Ulcer

• Focal loss of epidermis and dermis, that has variable shape, size and depth
• Penetrates into dermis, and heals with scarring

Morphology: Fissure

• A deep linear split in the skin often caused by drying, penetrates into dermis

Morphology: Scar

• Replacement fibrosis of the skin that results from destructive processes

Bacterial Infections - Overview

• Divided according causative agents that include Staphylococcus aureus, Corynebacterium minutissimum, and Streptococcus pyogen

Staphylococcus aureus

• Causes Impetigo, Folliculitis, Sycosis barbea, Furuncles, and Carbunculs

Corynebacterium minutissimum

• Causes Erythrasma

Streptococcus pyogen

• Causes Erysipelas, Cellulites, and Impetigo

Sensitivity to Antibiotics

• Topical antibiotics include Fusidic acid and mupirocin work for both Staph. aureus and Strep. pyogenes
• Neomycin works only with Staph. aureus
• Gentamicin not effective against Strep. pyogenes

Systemic Antibiotics

• Flucloxacilline and Erythromycin are effective against Staph. aureus and Strep. pyogenes

MRSA - Considerations

• Vancomycin can be used for MRSA Infections
• Linezolides considered more effective

Corynebacterium minutissimum - Topical Treatment

• Azol antifungal (miconazol & fluconazole), fucidic acid or mupriocin are Topical treatments

Corynebacterium minutissimum - Systemic Treatment

• Erythromycin & Tetracycline are Systemic treatments

Impetigo

• Superficial skin infection commonly seen in children and transmitted easily from person to another
• Caused by bacterial infection by Streptococci (developing countries) or Staphylococci (major pathogen)
• Primary cause: poor hygiene and moisture (common during summer)
• Secondary cause: insect bite, scabies, or scratch
• CBC is common
• Lesions are rarely painful but are pruritic

Types of Impetigo: Non Bullous

• Common in children; it is very contagious with a macule-vesicle-rupture with seropurulent discharge, or a honey-colored crust

Types of Impetigo: Bullous

• Most common in children under age two
• Larger blisters with larger bases/honey-colored crust.
• Fetal in new born infants, caused by S. aureus capable of producing exfoliative toxins
• Site: Trundk

Types of Impetigo: Ecthyma

• Serious form of impetigo affecting the second layer of the skin (painful)
• Ulcers with raised edges with necrotic crustation in the center; thick brown-black crust
• Heal with scar

Impetigo Treatment Considerations

• Antimicrobial treatment is indicated to relieve symptoms, prevent formation of new lesions, and prevent complications like cellulitis
• Topical local therapy requires removing of crust by water and soap

Impetigo Treatment - Mild Cases

• Topical antibiotic as fusidic acid cream 3 times (7-10 days)
• Mupirocin cream is effective if the cause of infection is MRSA

Impetigo Treatment - Widespread/Severe Cases

• Systemic antibiotics (penicillin, dicloxacillin flucloxacillin, cephalexin) are effective
• Azithromycin, Erythromycin and clindamycin effective in case of penicillin allergy.
• Clindamycin is given 300 mg every 6 hours for 7 days in adults, or 10-20 mg/kg every 8 hours for 7 days in children
• Trimethoprim-sulfamethoxazole is given 160 mg twice a day for 7 days in adults, or 8-12 mg/kg twice daily for 7 days in infants > 2 months
• Doxycycline is given 100 mg twice daily for 7 days in patients > 45 kg, and should not be given to children and pregnant women

Topical Treatments: First-Line Treatment For Impetigo

• Topical: Mupirocin 3 times for 7-10 days, bacitracin, fusidic acid.
• Topical Potassium permanganate 1/8000

Systemic Treatments: First-Line Treatment For Impetigo

• Dicloxacillin Penicillinase resistance penicillin for dosage 250-500 mg PO qid for 5-7 days
• Amoxicillin plus clavulanic acid; cephalexin for 25 mg/kg PO tid, and 250-500 mg PO qid for 10 days

Systemic Treatments: Second-Line Treatment (Penicillin allergy) For Impetigo

• Clindamycin or doxycycline is preferred for MRSA or if penicillin allergy, 
• Azithromycin: 500 mg PO × 1, and later 250 my PO daily for 4 days
• Clindamycin: 15 mg/kg/day PO tid for 7 days
• Erythromycin: 250-500 mg PO qid for 5-7 days

Ecthyma Treatments - Key Actions

• Topical treatments: Warm compresses qid
• Systemic treatments: Dicloxacillin at 250-500 mg PO qid for 5-7 days

Ecthyma Treatments -Amoxicillin

• Amoxicillin plus clavulanic acid at 25 mg/kg PO tid
• Cephalexin at 40-50 mg/kg/day PO for 10 days

Ecthyma Treatments (Penicillin Allergy)

• Use azithromycin at 500 mg PO × 1, then 250 mg PO daily for 4 days
• Clindamycin at 15 mg/kg/day PO tid for 10 days
• Erythromycin at 250-500 mg PO qid for 5-7 days

Folliculitis

• Superficial Pruritic Pustule around the upper part of hair follicle (ostium) & discrete (inflammation of hair follicles)
• Caused Staphylococcus aures
• Non-bacterial causes are shaving, waxing, wearing tight clothes or hair styling practices such as wigs and oils

Folliculitis - Other Considerations

• Steroid use, tight clothes, rubber gloves, boots that don't let sweat or heat out
• Poor hygiene , moisture, diabetes and HIV are risk factors

Folliculitis Treatments - Notes

• Identical to treatments for impetigo

Folliculitis Treatments - First Line

• Use fusidic acid, Bacitracin, clindamycin and Mupirocin topically between 5-7 days
• Apply warm compresses to promote drainage, Potassium permanganate 1\8000 
• Antiseptic wash (chlorhexidine) bid

Folliculitis Treatments - Next Steps

• Flucloxacillin, penicillin, Dicloxacillin, only if widespread or severe and use Doycycline (2-8 weeks) for MRSA
• If recurrent: eradicate S. aureus carriage (Mupirocin applied to nostrils and chlorhexidine wash, both daily for 5 days)

Sycosis Barbae

• Follicular pustules and papules in beard area
• caused by staphylococcus aures
• risk factors include poor hygiene, moisture and shaving

Furuncle

• Described as a peri-follicular, tender, hot, red nodule or pustule
• Deep infection in lower part hair follicle, with central necrosis
• More common in adults and carrier states.
• Obesity + DM are risk factors
• Important to exclude diabetes is in recurrent furunculosis

Carbuncle - Overview

• Affect multiple hair follicles beside each other.
• Furuncle coalesce into a fistula
• Occur in back, neck and intertriginous area
• DM + Obesity + prolonged use of corticosteroid are risk factors
• Systemic antibiotic + control the cause

Furuncle Treatments - First Line

• Incision and drainage should be avoided along with sqeezing,
• Apply warm compression that is indicated to facilitate drainage of small furuncles
• Large furuncles require incision and drainage, use dicloxacillin or flucloxacillin and Amoxicillin plus calvulanic acid; cephalexin, and duration of treatment is 1-2 weeks

Furuncle Treatments - Considerations

• Immunocompromised patients and severe infections or abscesses in patients who fail incision and drainage, plus oral antibiotics
• Treat empirically with parenteral vancomycin, daptomycin, linezolid, or ceftaroline

Recurrent Furunculosis Management

• Staphylococcus in the anterior nares, nasal swabs be be taken for culture and sensitivity
• Apply Mupirocin cream 2%, three times daily to eliminate nasal carriers of staphylococcus
• Exclude diabetes in recurrent furunculosis, use instructions of hygienic washing of hands, and clean lines
• Start Systemic Rifampicin that is effective in recurrent furunculosis with a dose of 600 mg daily for 1 week each month for 3 months
• Ciprofloxacillin or clindamycin are also used

Erysipelas - Overview

• Swallow erythema inflammation and hotness, with sharp border
• DM, and immunocompromised patients are risk factors
• Cellulites have an ill-defined border

Cellulities and Erysipelas

• Cellulitis results in inflammation of lower dermis and SC tissue with Staph aureus (purulent )and Streptococcus pyogenes whereas Erysipelas is of the upper dermis cause by ẞ hemolytic streptococci
• Patients mention burning pain
• Clinical Picture: face and leg commonly affected/red non-edematous for erysipelas, and for cellulitis commonly affect lower limbs/ pink edematous

Treatments for Cellulitis and Erysipelas Considerations

• Provide symptomatic treatment pain and fever and Underlying predisposing conditions, should be identified like diabetes, for sinus infection to prevents recurrences (in facial erysipelas)
• Prompt systemic Antibiotics if the infection is deep and Oral penicillin is to be given for uncomplicated mild cases, and IV therapy for systemic toxicity
• Consider Amoxicillin and clavulanic acid is if there is evidence of sinus infection

Treatments for Cellulitis and Erysipelas Steps

• Penicillin resistant infection suspected, use clindamycin or substitute with intravenous linezolid
• For severe cellulitis and erysipelas due to MRSA, vancomycin is needed.
• For mild cases it is needed between 5-10 days and Complicated cases, 10-20 days is required

Strategy for Cellulitis and Erysipelas Treatment

•  MILD, no evidence of systemic signs or symptoms, and Well-controlled: use Cephalexin, Penicillin VK, and Dicloxacillin oral
• MODERATE for evidence of systemic signs: Cefazolin or Ceftriaxone IV medications
• SEVERE if Presences of SIRS with altered mentation, toxic appearance:  Vancomycin+/-,Piperacillin/Tazobactam,Meropenem/Imipenem, and Linezolid IV methods

Cellulitis and Erysipelas Treatments - Additional Factors

• Both these illnesses treated with outpatient therapy
• Hospitalize patients with systemic inflammatory response syndrome (SIRS) for temperature, tachypnea or tachycardia and abscess.
• Use Low-dose antibiotic prophylaxis with penicillin v 250 mg twice daily for 5-7 days every month for 12 months
• Consider I.M benzathine penicillin once a month for 12 months

Erythrasma

• Itchy, Irregular but well defined brown patch with superficial scales and found in intertrigenios area, axilla , groin, sub mammary area.
• Mild, chronic and superficial bacterial infection and the DD is tinea cruris and candida infection
• Superficial infection with corynebacterium minutissimum in intertriginous area (Obesity + DM, Heat, Moisture + poor hygiene)

Erythrasma Treatments

• Topical include fusidic acid, clindamycin, mupirocin antibiotic agents with antifungul Azole derivatives
• Systemic for severe discrete cases uses Erythromycin at 250 mg 4 times daily for 14 days,
• Tetracycline, and Single 1 g clarithromycin dose

Case 1 - Male 40. Erythema left leg, well demarcated, chills and malaise. Diagnoses?

• Erysipelas, difficult to differentiate between cellulitis and Erysipelas

Case 1 - Male 40. How to treat cellulitis with erythema?

• IV antibiotic over 5 - 10 days

Case 1 - What if patient has Penicillin Allergy? what is the treatment?

• Use clindamycin 600 mg 8 hourly IV

Case 1 - What if the patient doesn't get treated? Complications?

• Possibilities include subcutaneous and septicemia. 

Case 1 - How do you know the patient has Erysipleas vs DVT?

• Doppler ultrasound examination may be helpful,
• Protein levels higher in cellulitis

Case 2 - Jan is 12 , thin walled vesicle face

• Thin walled vesicle = Imetigo, the treatment would be systemic antibiotic , Topical antiseptic.
• Possible Glomerulonephritis as a compication.

Case 3 - Dora 23 years old women with patch scaly, reddish-brown

• Diagnoses - Enthrasama, and uses azyol agents.
• Long term pordone iodine, drying agents to help prevention.

Leprosy: Overview

• Also known as Hansen's Disease, a chronic, granulomatous infection caused by Mycobacterium leprae, bacterium related the bacteria causing tuberculosis.
• Affects skin and nerves and transmitted mostly through nasal mucosa by droplets or wounds and
• Through nasal mucosa to site of macrophages (intracellular

Leprosy: Key Symptoms

• Sensory Hypothesia, Motor Weakness, facial palsy and Autonomic Decreased Sweating and hyperpigmentation

Classification

• Bacteriological consists of Paucibacillary leprosy or Boroder line, whereas Clinical Consists Of Lepromatous and Border Lin

Leprosy Spectrum

• Paucibacillary has Better Immunity and Multibacillary Leprosy has bad.

Tuburcoid Leprosy

• Characteristic nerve enlargement + Skin of nervial area.
• Good immunity, not highly contagious

Lepromatous Leprosy

• Good immunity, no highly contagiois only if untreated and released into air.

Leprosy - Treatment

• PB including SLBP or rifampcin, and should be 6 months. 
• Treat at lease -2 years

Case STudy: MAle with 5+

• Best treatment, MB with 12 motnhs of treatment.

Learn about the structure and function of the skin covering Epidermis, Dermis, and Subcutaneous fat along with their functions. Also learn about primary skin lesions, including macules, papules, vesicles, and wheals, and their characteristics.