Viral Skin Infections

Viral diseases have caused havoc, as evident from the 2020 COVID-19 pandemic. Viruses can remain dormant. Viruses are often known as borderline organisms as they don't reproduce by themselves, but they can when they come in contact with living organisms and reproduce or multiply inside the organism. They have the ability to replicate in the toughest conditions. They can either have RNA or DNA as the genetic material. 

Let us study viral infections that primarily affect the skin and cause problems. This is a high-yield topic for all the competitive exams in India, such as NEET PG and FMGE.

We will discuss each viral skin infection one by one. 

1. Molluscum Contagiosum

• The Virus that causes Molluscum contagiosum is Molluscum contagiosum virus (MCV)
• It belongs to the Family of POXVIRUS. 
  • Poxvirus is the largest known virus.
  • It is a DNA virus 
• Molluscum infection is of two Types
  • MCV 1 - mainly seen in children 
  • MCV 2 - mainly seen in adults
    • Sexually transmitted

Also read : Lichen Sclerosus: Causes, Symptoms, Risk Factors, Diagnosis, Treatment and Complications

Clinical Features of Molluscum Contagiosum

• Asymptomatic in nature.
• Common in childhood.
• There is a Positive family history. 
• Face and other body parts are mainly affected.
• If it is present in the genital area, then sexually transmitted infections should be ruled out.
• The lesion in the molluscum contagiosum infection looks like an umbilicated papule. These Umbilicated papules are skin-colored or red in appearance and have a Central indentation.
• Pseudo Koebner’s Phenomenon is seen in the case of molluscum contagiosum.

Histopathology of molluscum contagiosum

• Eosinophilic intracytoplasmic inclusion bodies - Henderson Patterson Bodies

Treatment of molluscum contagiosum:

• Self-resolution is seen in most cases. 
• No oral treatment is needed in normal cases.
• If there are many lesions, if the lesions are in adults, or if the lesions do not respond, then further treatment is needed.

Also read : Morphea: Causes, Symptoms, Risk Factors, Diagnosis, Treatment and Complications

2. Ecthyma contagiosum 

It is a zoonotic infection acquired from animals and passed on to humans. The causative agent is the Parapoxvirus / ORF virus. It is mainly seen in individuals who rear sheep.

3. Milker's Nodule 

It is caused by Pseudopox. It is seen in individuals who rear cows. The appearance of Milker’s nodule is usually present on exposed body parts as an erythematous bluish papule. This usually leads to pus formation, which later creates crusted lesions.

4. Human Papillomavirus (HPV)

• They cause warts/verruca.
• There are more than 200 subtypes of HPV.
• Different subtypes cause different kinds of warts.
• They are usually asymptomatic.
• The growth is hyperkeratotic/ verrucous in nature.
• HPV: Types of Viral Infection

These can be remembered using a Mnemonic - DSP Come Eat A Burger.

1. HPV 1 - Deep plantar wart
2. HPV 2 - Superficial plantar warts
3. HPV 3 - Plane warts
4. HPV 4 - Common warts
5. HPV 5 - EDV- epidermodysplasia verruciformis
6. HPV 6 - Anogenital warts
7. HPV 7 - Butcher’s warts

• Let us read about warts in detail as they are commonly seen in the dermatology OPD. 

1. Common warts are also known as verruca vulgaris. 
   • Common warts are Asymptomatic.
   • They are Hyperkeratotic growths.
   • They show pseudo-Koebner’s phenomenon.
2. Plane warts are also known as verruca plana. They are:
   • The top of the lesion is the plane.
   • Commonly seen on the face.
   • Caused by HPV 3 and HPV 10
   • Usually seen in immunocompromised patients (HIV-positive patients, transplant patients, patients undergoing chemotherapy)
   • If the skin is breached, the transmission can occur via fomites or person-to-person.
3. Plantar warts 
   • Types
     • Superficial: HPV 2 —> Mosaic pattern
     • Deep : HPV 1 —> Myrmecia
   • They are Painful in nature
   • Commonly seen in children
4. EDV - Epidermodysplasia Verruciformis
   • Caused by HPV 5 & HPV 8
   • Genetic tendency to widespread HPV infections - Autosomal recessive
   • Increased risk of squamous cell carcinoma

• Presents with 3 Ps
  • Plane warts
  • Pityriasis versicolor-like lesions
  • Reddish plaques

5. Anogenital warts

• It is important to rule out sexually transmitted infections.
• It is also called Condyloma acuminata.
  • Condyloma: broad-based
  • Acuminata: pointed
• In males, it is present on the sulcus.
• In females, it is present on the fourchette (site of sexual trauma).
• Lesions are softer than other warts.
• Low-risk type: HPV 6, 11
• High-risk type: HPV 16,18,31,33 (predispose to malignancy)

6. Giant condyloma accuminata

• Buschke Hyphen Lowenstein Tumor
• High risk of malignant transformation

Also read : Balanitis: Causes, Symptoms, Risk Factors, Diagnosis and Treatment

Histopathology of HPV

• Clear-looking cells with nuclear condensation in the center and perinuclear halo are called Koilocytes.

Treatment of HPV

• There is no particular oral treatment for HPV, but levamisole or zinc can be given for immunomodulation.
• The main aim is to destroy the virus, which the following methods can do:

• There are high chances of recurrence. 
• Treatment of choice in case of
  • Genital lesions - podophyllin, imiquimod, TCA
  • Pregnancy - cryotherapy, TCA
  • Intraurethral, rectal - TCA

5. HHV - Human Herpes Virus 

HSV 1 and 2 

• HSV 1 - above waist infections
• HSV 2 - below waist
  • Genital lesions 
• The site of infection is, however, not exclusive 
• HSV causes Three kinds of infections:
  • Primary infections
  • Secondary/recurrent 
  • Subclinical shedding
• HSV gets latent in the dorsal root ganglion
• Even when they are clinically normal/asymptomatic, they continue to shed the virus.
• Primary infection is more severe
• Secondary infection is milder
• Let us read about some important types of herpes infections:

1. Herpetic Gingivostomatitis
   • It is the most common cause of gingivostomatitis in children
   • Coalescing vesicles which rupture to form polycyclic erosions
   • Painful 
2. Herpes Labialis

• It is also known as a Cold sore
• The virus may stay latent and thus also known as secondary infection
• It is less severe
• It is usually present on the vermillion border of lips 
• It is slightly painful and can cause mild discomfort 
• Predisposing factors to herpes labislis:
  • Fever 
  • Stress
  • Menstrual cycle
  • Surgery

Latent in Trigeminal ganglion

Also read : Chilblains: Causes, Symptoms, Risk Factors, Diagnosis, Treatment, Prevention and Complications

3. Genital Herpes

• It is also called herpes genitalis. It is Caused by HSV 2. It is a sexually transmitted infection and is a part of Genital Ulcer Disease (GUD)
• Three kinds of infection: Primary, Secondary/ Recurrent, and Subclinical shedding
• Superficial fluid-filled painful coalescing vesicles that rupture to form polycyclic erosions.
• It is associated with painful lymphadenopathy.
• The primary infections take 7 days to heal.
• The secondary infection takes 3-5 days to heal.
• Incubation period: 2-7 days.
• Recurrent herpes genitalis: >6 episodes/year

4. Herpetic Whitlow

• It generally affects Fingertips. 
• Vesicles rupture to form polycyclic erosions.

5. Herpetic Gladiatorum

• This type of herpes is present on the Trunk of boxers/wrestlers

Complications of HSV 

• Bells’ Palsy 
• Hepatitis, encephalitis 
• Erythema Multiforme
  • Reaction patterns to drugs, HSV, or other causes
  • The most common infectious cause of EM - HSV 
  • It has characteristic Target lesion - Palms, soles/trunk
• Eczema Herpeticum/
  • Usually in children
  • Occurs on Preexisting dermatosis - mostly Atopic Dermatitis / Darier’s / Pemphigus
  • On compromised skin barrier →   HSV → numerous vesicles suddenly on preexisting dermatosis
  • Treatment of eczema herpeticum

Oral steroids are given in cases of flare-ups. However,t because this is an HSV infection, the treatment is Acyclovir.

Diagnosis of HSV

• Tzank smear is done for HSV
  • Smear from the base of a vesicle 
  • Acantholytic cells -seen 
  • Multinucleated giant cell are also seen which are specific for HSV.
• Serology
  • IgG - past infection
  • IgM - recent infection

Also read : Chilblains: Causes, Symptoms, Risk Factors, Diagnosis, Treatment, Prevention and Complications

Treatment of HSV

• TOC - Acyclovir 400mg TDS / 200 mg five times a day 

• Acyclovir-resistant cases - FOSCARNET 

6. HHV 3 - Varicella Zoster Virus - VZV

• Varicella/chickenpox
• Herpes zoster

1. Chickenpox 
   • Primary infection
   • The virus stays latent in dorsal root ganglion → Herpes Zoster 
   • Incubation period - 2-3 weeks
   • Usually seen in children
   • Prodromal/constitutional symptoms:
     • Fever 
     • Malaise

Characteristics of Rash in chicken pox:

• Polymorphic
  • Multiple morphologies of lesions at the same time 
  • Vesicles
  • Papules  
  • Macules 
  • Crusted erosions
• Morbilliform - red
• Centripetal - starts from the trunk and spreads peripherally
• Vesicles on an erythematous background - Dewdrop on a Rose Petal appearance.

Symptoms of chickenpox

• Itching/discomfort 
• Usually, painless
• High transmission rate 

Complications of chicken pox

• Encephalitis 
• Meningitis

Pre-exposure prophylaxis in chicken pox

• Vaccine- Oka strain
• 2 doses spaced 3 months apart are given

Post-exposure prophylaxis in Chickenpox

• Acyclovir 
• IV Immunoglobulins

Treatment of chickenpox

• Supportive 
• Topical antibiotics
• Acyclovir is only given in
  • Severe cases
  • In immunocompromised 

1. Herpes Zoster
   • Varicella virus is latent and gets reactivated
   • Latent in dorsal root ganglion
   • Seen in
     • Elderly 
     • Immunocompromised- Patients on Chemotherapy
   • Herpes Zoster - Dermatomal Distribution

• Present on one side of the body along one dermatome (dermatomal distribution).
• It is extremely painful because of nerve trunk involvement.
• Paraesthesia / altered sensation may be present.
• Most common dermatome - thoracic > cervical > trigeminal > lumbosacral

Complications of Herpes Zoster virus

1. Herpes zoster ophthalmicus
   • Conjunctivitis
   • Uveitis
   • Indication for oral corticosteroids
   • Hutchinson’s Sign
2. Ramsay Hunt Syndrome
   • Geniculate ganglion
   • Trigeminal and facial nerve
     • Vesicles on tympanic membrane→ ear pain, tinnitus 
     • Facial palsy, vesicles on tongue
3. Postherpetic Neuralgia 
   • If pain persists for more than 3 months after herpes zoster 
   • Some say> 1 month 
   • Pain / neurological symptoms
   • Extremely painful
   • Treatment of postherpetic ganglia: Gabapentin, Pregabalin, and Tricyclic antidepressants

Treatment of Herpes Zoster virus

• Acyclovir - 800 mg five times a day for 7 - 10 days
• Treatment should be started Within 48 - 72 hours 

7. HHV - 4 - Epstein Barr Virus

Human Herpes virus 7 or Epstein Barr virus causes the following diseases: 

1. IMN - infectious mononucleosis 
   • Glandular fever /kissing disease
   • Exanthem is present
   • Forscheimer spots may be seen 
   • It presents with Fever and sore throat 
   • If the patient is given antibiotics → amoxicillin, ampicillin causes a rash known as AMPI RASH 
2. Oral Hairy Leukoplakia
   • Whitish patches are present on the tongue's lateral border, which cannot be removed by scraping.
   • Commonly seen in HIV patients 
3. Other EBV Associated Diseases 
   • Burkitt’s Lymphoma
   • Hodgkin’s Lymphoma
   • Nasopharyngeal Carcinoma

8. HHV - 6 and 7 

• It causes pityriasis, rosea, and roseola infantum.
• It acts as a trigger for lichen planus

1. Roseola Infantum

• It is also known as Exanthem subitum, where Exanthem means diffuse red rash and Subitum means sudden onset. Roseola denotes its red color.
• Seen In infants < 2 years

Fever 

⬇

Subsidies in 3- 5 days 

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Suddenly, a rash appears on the trunk. 

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Rose red-colored papules 

1. Pityriasis Rosea 

• Caused by HHV - 6 and 7
• PITYRIASIS means scaly.
• It occurs 2 -3 weeks post URTI/GI infection.
• The appearance of the first erythematous lesion on the trunk is called the Herald’s patch.
• It is surrounded by scales in a collar-like fashion: collarette of scales
• After 1-2 weeks, numerous scaly lesions appear all over the body.
• Christmas Tree / Fir Tree Pattern is seen along the lines of the cleavage.

9. HHV - 8 Kaposi Sarcoma

Deep bluish vascular lesions are present. They are usually seen in HIV-positive patients.

10. Parvovirus B19

Parvovirus B19 causes erythema infectiosum. A slapped cheek appearance is seen.

10. Enteroviral Disease

It includes certain diseases, which are as follows:

1. HFMD - Hand, Foot and Mouth Disease

The Causative organisms of hand, foot and mouth disease is Coxsackie A16 & Enterovirus 71. It is usually seen in children. Vesicles and erythematous papules are seen over the hands, foot, and mouth. Fever and other constitutional symptoms may be present.

2. Herpangina

The Causative organism for Herpangina is Enterovirus 71. In this disease Coalescing erosions are seen on the palate.

3. Measles

A morbilliform rash is seen in measles. Koplik’s spots are present on the opposite side of the premolars. The rash is present behind the ear, neck, and trunk.

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