Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Dermatology PPT 31 Viral Infection Lecture Notes
Cutaneous Viral Infections
Definition
? Virus: A virus particle or `virion', is a length of nucleic
acid (either RNA or DNA), within a protein shell, the
capsid
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
Aetiopathogenesis
? Cell lysis (Herpes)
? Cell proliferation (Pox, HPV)
? Carcinogenesis (Cervical Ca [HPV], hepatoma
[HCV, HBV])
?Exanthemata - Viraemia, type 3 hypersensitivity
(Arthus) reaction, virus lodged in dermal capillaries &
replicate
?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
warts
? 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
?Autoinoculation
Clinical Types
Extra-genital (non-genital)
?Verruca vulgaris (Common warts)
?Verruca plana (Plane warts)
?Filiform
?Digitate
?Palmoplantar
?Periungual
Genital
?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,
coalesce
?Koebner's phenomenon +
?Sites: face, neck, extremities
Filiform
?Finger like projection
Digitate
?Multiple finger like projections with a common base
?Sites: head, face and neck
Clinical features
Palmoplantar
?Hyperkeratotic elevated or flat lesions, painful on
lateral pressure
?Differential diagnosis: Corn, callosity
Periungual
?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
?Premalignant
Complications
?Secondary infection
?Pregnancy related:
Proliferative growth, obstruction of labour,
laryngeal papillomas in infant / child
?Malignant change:
Buschke-Lowenstein tumor (verrucous
carcinoma)
Cervical intraepithelial neoplasia (HPV 16, 18)
Investigations
?Clinical diagnosis
?Histology: Papillomatosis, acanthosis with
inclusion bodies causing vacuolation in cells
(Koilocytes)
?Immunohistochemistry: Type of HPV
Treatment
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
Treatment
Immnomodulators
? 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
papules
?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
Treatment
?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 +
Complications
?Secondary infection
?Encephalitis
?Pneumonitis
?Hepatitis
?Varicella in HIV- Progressive, haemorrhagic,
complicated
?Chronic varicella- Hyperkeratotic lesions, acute
retinal necrosis
Treatment
?Symptomatic
Rest, Antibiotics, NSAIDs, antihistamines
?Acyclovir
Dose: 800 mg 5 times / day
Indicated in adult varicel a
Reduces severity, duration & infectivity in childhood
chicken pox
?Prophylaxis
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
commonly)
?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
Complications
?Secondary infection
?Post herpetic neuralgia
?Scarring
?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
Treatment
?Symptomatic
?Antivirals
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
?Gabapentin
?Pregabalin
?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
?Reactivation
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,
keratoconjunctivitis
?Herpes simplex virus 2
Herpes genitalis, herpes vulvovaginitis
?Complicated
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
?Aphthosis
?Erythema multiforme
?Behcet's syndrome
?Pyodermas
?Genital ulcer disease e.g., chancroid
Investigations
?Tzanck smear: Multinucleated giant cells
?Histopathology: Ballooning degeneration,
intraepithelial blisters, inclusion bodies
?HSV antibody titre: IgG / IgM ? not very reliable
?Culture
?Immunofluoroscence, PCR
?Electron microscopy
Treatment
?Symptomatic
?Topical - Acyclovir, penciclovir, cidofovir
?Systemic
Antiviral
Primary
Recurrence
Suppressive
(10 days)
(5 days)
6 months - 1yr or
longer
Acyclovir 200 mg 5 times 400 mg TDS
400 mg BD
/ day
Valaciclovir
1 gm BD
500 mg BD
500 - 1000 mg BD
Famciclovir
250 mg TDS
125 mg BD
250 mg BD
Viral Exanthems
Macular
?Rubel a
?EBV (infectious mononucleosis)
?Human herpesvirus 6 (roseola)
?Human herpesvirus 7
Maculopapular
?Togavirus
?Measles
?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)
Urticarial
? 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
fever
?Picorna Viruses
Herpangina
Hand, foot & mouth disease
Thank you
This post was last modified on 07 April 2022