Download MBBS Dermatology PPT 31 Viral Infection Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Dermatology PPT 31 Viral Infection Lecture Notes

Cutaneous Viral Infections


? Virus: A virus particle or `virion', is a length of nucleic

acid (either RNA or DNA), within a protein shell, the

DNA viruses

RNA viruses

? Herpes simplex

? Retrovirus

? Varicel a-zoster

? Togavirus

? Human papil oma

? Flavivirus

? Poxvirus

? Paramyxovirus

? HHV 6,7 & 8

? Hepatitis A, C & E

? Epstein Barr

? Picornavirus

? Parvovirus
? Hepatitis B


? Cell lysis (Herpes)

? Cell proliferation (Pox, HPV)

? Carcinogenesis (Cervical Ca [HPV], hepatoma
?Exanthemata - Viraemia, type 3 hypersensitivity

(Arthus) reaction, virus lodged in dermal capillaries &

?Persistent infection - Periods of latency & reactivation

(HSV recurrence attacks of HSV labialis or genital
lesions; VZV herpes zoster)

Common Viral Infections of Skin

?Human Papilloma Virus: Genital & extra-genital


? Pox Virus: Molluscum contagiosum

? Varicella-zoster Virus: Varicella, Herpes zoster

? Herpes Simplex Virus 1 & 2: Herpes simplex

? Viral Exanthemata
Human Papil oma Virus

?DNA virus, about > 200 types described til date
?Carcinogenic ? anogenital, cervix
?Incubation period: few weeks to about one year
?Transmission: direct or indirect contact (nail

biters, shaving, occupational, swimming pool)

?Sexual transmission: genital / perianal wart

Clinical Types

Extra-genital (non-genital)
?Verruca vulgaris (Common warts)
?Verruca plana (Plane warts)

?Condyloma acuminata
Clinical features

Skin warts are benign tumours caused by infection

of keratinocytes with HPV, visible as welldefined

hyperkeratotic protrusions

Verruca vulgaris:
?Commonest type of warts
?Children and young adults affected
?Asymptomatic, hyperkeratotic papular lesions

with warty excrescences
?Common Sites: Extremities, dorsae of hands & feet
?Koebner's phenomenon present

Clinical features

Verruca plana
?Juvenile/ flat warts
?Discrete flat skin colored or pigmented papules,

?Koebner's phenomenon +
?Sites: face, neck, extremities
?Finger like projection

?Multiple finger like projections with a common base
?Sites: head, face and neck

Clinical features

?Hyperkeratotic elevated or flat lesions, painful on

lateral pressure

?Differential diagnosis: Corn, callosity

?Commonly associated with palmoplantar warts
?Invasion of nail bed
?Recalcitrant to Rx
Genital Warts

Condyloma Acuminata
?Protuberant moist, cauliflower like growths
?Sites: frenulum, corona & glans in men &
posterior fourchette in women
?Anogenital warts in children: sexual or non-sexual

transmission; may be sign of sexual abuse
Bowenoid Papulosis
?Multiple, grouped, warty lesions on genitalia


?Secondary infection
?Pregnancy related:
Proliferative growth, obstruction of labour,

laryngeal papillomas in infant / child

?Malignant change:
Buschke-Lowenstein tumor (verrucous


Cervical intraepithelial neoplasia (HPV 16, 18)

?Clinical diagnosis
?Histology: Papillomatosis, acanthosis with

inclusion bodies causing vacuolation in cells


?Immunohistochemistry: Type of HPV


No treatment ? spontaneous clearing may occur

?Topical Keratolytics - Salicylic acid lotion; wart

paints (lactic acid / salicylic Acid)
?Chemical cautery: TCA, liquified phenol
?Podophyllin / podophyllotoxin resin ?

anogenital warts (CI ? pregnancy)
?Cryotherapy (liquid N2 / CO2)
?Electrocautery / radiofrequency surgery
?Others: Imiquimod, 1% & 5% 5-FU creams,

photodynamic therapy

? Levamisole, cimetidine, zinc

Vaccines (immunotherapy)
? Mw vaccine, MMR vaccine, Trichophytin

Mol uscum Contagiosum

?Pox Virus- Molluscum contagiosum virus

?MCV 1 & MCV 2

?Incubation period: 2 weeks to 6 months

?Transmission: contact, fomites, sexual

?Histology: Intracytoplasmic inclusion bodies (aka

Henderson-Paterson bodies)
Clinical features

?Dome shaped, pearly white, discrete umbilicated


?Koebner's phenomenon present

?Sites: Face, neck, trunk, around genitalia (more in

sexual transmission), eyelids

?Giant molluscum lesions / secondary infection

Mol uscum Contagiosum in HIV

?Commonly on genitals, perianal region, eyelids

?Refractory mollsca on face; disseminated lesions

may be present

?D/D: Cryptococcosis, histoplasmosis, penicillinosis

?Expression / Curettage

?Chemical cautery, electrodessication, cryotherapy.

?Topical: Imiquimod, KOH, liquified phenol,

cantharidine, cidofovir cream

?Systemic: Levamisole, cimetidine

Varicella-Zoster Virus

?Chicken pox (varicella) & shingles (herpes zoster)

?Transmission: Droplet infection - nasopharynx

?Varicella : Primary viraemia

?Zoster: Reactivation of residual latent virus in the

dorsal nerve root ganglia
Varicella - Clinical features

?Incubation period: 2-3 weeks

?Prodromal symptoms ? malaise, fever, sore throat,

bodyache etc.

?Pleomorphic, centripetal distribution, dewdrops

on rose petal appearance

?Vesicles, papulovesicles, crusting, haemorrhagic,

umbilicated lesions

?Mucosal involvement +


?Secondary infection




?Varicella in HIV- Progressive, haemorrhagic,


?Chronic varicella- Hyperkeratotic lesions, acute

retinal necrosis


Rest, Antibiotics, NSAIDs, antihistamines


Dose: 800 mg 5 times / day

Indicated in adult varicel a

Reduces severity, duration & infectivity in childhood
chicken pox


Vaccine, Immunoglobulin (VZIg; IVIg), Acyclovir (IV)

Herpes Zoster

Clinical Features
?Reactivation of latent virus in the dorsal root

ganglion of sensory nerve

?Older age group , diabetics, HIV infection / AIDS

?Unilateral, dermatomal, grouped vesicles
?Cranial (V, VI commonly), spinal (thoracodorsal


?Pre-herpetic, herpetic and post-herpetic neuralgia
Herpes Zoster : Cranial nerve involvement

V Nerve
?Ophthalmic division: Herpes zoster ophthalmicus

Hutchinsons sign (vesicles on nose tip)

Ocular complications: uveitis, keratitis,

conjunctivitis, scleritis, ocular palsy

?Maxillary division: uvula / tonsils

?Mandibular division : tongue / buccal mucosa

Herpes Zoster : Cranial nerve involvement

VI nerve

?Ramsay Hunt syndrome

?Earache, vesicles on pinna, facial palsy

?Hearing loss, vertigo & taste sensation impaired

?Secondary infection

?Post herpetic neuralgia


?Nerve Palsy

?Encephalitis: in disseminated zoster

Herpes Zoster in HIV

?Younger patient

?Severe pre-, herpetic and post-herpetic neuralgia

?Multi-dermatomal, cranial nerve involvement

?Haemorrhagic, disseminated

?Protracted course, verrucous lesions

?Acute retinal necrosis



Acyclovir 800mg x 5times/day

Famciclovir 250-500 mg TDS

Valaciclovir 1gm TDS

Duration: 1 week in immunocompetent

2 weeks or more in immunosuppressed

Treatment of post herpetic neuralgia

?Analgesics- NSAIDs- not much efficacy
?TCAs- Amitryptiline, Nortryptiline
?Sodium valproate
?Topical EMLA cream
?Topical capsaicin ? causes irritation
Herpes Simplex Virus

?HSV 1: Facial (above waist)

?HSV 2: Genital (sexual)

?Incubation Period : 3-7 days

?Primary infection

?Persist in sensory ganglion - period of latency


Clinical features

?Grouped vesicles on erythematous base followed

by erosions and healing

?Primary attack: severe with lymphadenopathy and

systemic complaints

?Recurrences: mild with shortened clinical course

?Predisposing factors: trauma, sunburn, stress,

coitus, premenstrual, high grade fever, infections,
surgery, dermabrasion
Herpes Simplex- Clinical Types

?Herpes simplex virus 1

Herpes labialis, herpetic gingivostomatitis,

?Herpes simplex virus 2

Herpes genitalis, herpes vulvovaginitis


Eczema herpeticum (Kaposi's varicelliform eruption),
Disseminated HSV

?Herpes simplex virus in HIV infection / AIDS

Chronic, recurrent, ulcers with eschar formation;
dissemination can occur
Differential diagnosis

?Erythema multiforme
?Behcet's syndrome
?Genital ulcer disease e.g., chancroid


?Tzanck smear: Multinucleated giant cells
?Histopathology: Ballooning degeneration,
intraepithelial blisters, inclusion bodies
?HSV antibody titre: IgG / IgM ? not very reliable
?Immunofluoroscence, PCR
?Electron microscopy

?Topical - Acyclovir, penciclovir, cidofovir





(10 days)

(5 days)

6 months - 1yr or


Acyclovir 200 mg 5 times 400 mg TDS

400 mg BD

/ day


1 gm BD

500 mg BD

500 - 1000 mg BD


250 mg TDS

125 mg BD

250 mg BD

Viral Exanthems


?Rubel a
?EBV (infectious mononucleosis)
?Human herpesvirus 6 (roseola)
?Human herpesvirus 7


?Human parvovirus B19 (erythema infectiosum)
Viral Exanthems

Maculopapular - vesicular
? Coxsackie A (5, 9, 10, 16)
? Echovirus (4, 9, 11)
Maculopapular - petechial
? Togavirus (Chikungunya)
? Bunyavirus haemorrhagic fever (lassa)
? Coxsackie A9
? Hepatitis B

Uncommon Viral Infections of the Skin

? Pox Viruses
Cowpox, orf, milker's nodule

? Epstein Barr Virus (EBV)
Infectious mononucleousis, oral hairy leukoplakia (OHL),

Gianotti Crosti syndrome, lymphomas

? Viral (insect-borne & haemorrhagic) fevers

(Toga, Flavi, Arena, Filo, Bunya)
Chikungunya, dengue, Kyasanur forest disease (KFD), lassa


?Picorna Viruses
Hand, foot & mouth disease

Thank you

This post was last modified on 07 April 2022