Histopathology of Viral Skin Infections

Histopathology of Viral Infections

• Keratinocytes show "ballooning degeneration" with margination of chromatin, eosinophilic nuclear inclusions, and multinucleate giant cells.
• Vesicles rupture and become erosions.

Human Herpes Virus (HHV)

• Double-stranded DNA virus with two types: HSV-1 and HSV-2.
• Lytic to human epithelial cells and latent in neural tissue.
• Clinical features:
  • May penetrate intact mucous membrane, but requires breaks in skin.
  • Infects peripheral nerve, migrates to regional ganglion.
  • Primary infection, latency, and recurrence occur.
  • 99% of cases are sub-clinical in childhood.

Primary Herpes: Acute Herpetic Gingivostomatitis

• 1% of cases; severe symptoms in children (1-3 years) and occasionally in adults.
• Incubation period: 3-8 days.
• Numerous small vesicles in various sites in mouth; vesicles rupture to form multiple small shallow punctate ulcers with red halo.
• Child is ill with fever, general malaise, myalgia, headache, regional lymphadenopathy, excessive salivation, and halitosis.
• Self-limiting; heals in 2 weeks.

Secondary Herpes: Recurrent Oral Herpes Simplex

• Presents as:
  • Herpes labialis (cold sores) or
  • Recurrent intra-oral herpes – palate or gingiva.
• Seen in adults (approx 30%).
• Predisposing factors: sunlight, fever, allergy, trauma, menstruation, and immunosuppression.
• Herpes labialis:
  • Prodrome of burning and tenderness.
  • Intraepithelial blisters which burst, crust, and heal in 10-12 days.
• Recurrent intra-oral herpes (uncommon):
  • Vesicles rupture early, form ulcers with red or white bases.
  • Heal in 10-12 days.

Human Papilloma Virus (HPV)

• Benign proliferation of stratified squamous epithelium resulting in a papillary or verruciform mass.
• Etiology: Human papilloma virus (HPV).
• Clinical features:
  • M=F; 30-50 years.
  • Site: Tongue; Lips; Soft palate (common); any oral surface.
  • Soft, painless, pedunculated, exophytic nodule with surface finger-like projections (cauliflower-like).
  • Normal color.
  • Solitary, 0.5mm; occasionally multiple lesions occur.

RNA Viruses: Picorna Virus (Coxsackie)

• Coxsackie A viruses cause:
  • Herpangina
  • Hand, foot, and mouth disease
  • Acute lymphonodular pharyngitis
• Most cases arise in summer/early fall.
• Spread: fecal-oral route.

Herpangina

• Multiple Coxsackie subtypes.
• Sore throat, dysphagia, fever.
• Occasional cough, rhinorrhea, anorexia, vomiting, headache, and myalgia.
• Oral lesions, confined to posterior sites: soft palate, tonsil; begin as red macules and petechiae, form vesicles and ulcerate (2-4mm).
• Heals within 7-10 days.

Hand, Foot, and Mouth Disease

• Coxsackie subtypes A9 and A16.
• Sore throat, dysphagia, fever.
• Occasional cough, rhinorrhea, anorexia, vomiting, headache, and myalgia.
• Skin rash on palms and soles.
• Oral and hand lesions almost always present; other sites variable.
• Oral lesions similar to herpangina but not confined to posterior mouth.

Acute Lymphonodular Pharyngitis

• Yellow to dark pink nodules develop on soft palate and/or tonsillar pillars.
• Nodules are hyperplastic lymphoid aggregates.
• Resolves within 7-10 days.

Acquired Immune Deficiency Syndrome (AIDS)

• A human immunodeficiency state caused by the human immunodeficiency virus (HIV) and associated with several life-threatening opportunistic infections and malignant neoplasms.
• Etiology:
  • Human immunodeficiency virus (HIV)
• Susceptible individuals and predisposing factors:
  • Homosexual/bisexual men (sexual intercourse)
  • Intravenous drug users (contaminated needles)
  • Haemophiliacs (via infected blood transfusions)
  • Heterosexual contacts (sexual intercourse)
  • Vertical transmission – mother to child (in-utero)
• Clinical features:
  • Fever, generalized malaise, unexplained weight loss, night sweats, lymphadenopathy (persistent cervical, axillary, and inguinal), diarrhea, and persistent cough.
• Associated infections:
  • Pneumocystis carinii (pneumocystis pneumonia)
  • Candidiasis (oral and genital)
  • Herpes (oral, genital, ocular, encephalitis)
  • Cytomegalovirus (CMV) in kidney, lung, and brain
  • Mycobacterium avium intracellulare
• Associated malignant neoplasms:
  • Kaposi's sarcoma (hard palate, gingiva, skin)
  • Lymphoma
  • Squamous cell carcinoma of the oral cavity
• Oral findings:
  • Hairy leukoplakia on lateral borders of tongue
  • Candidiasis
  • Recurrent herpes simplex infections
  • Kaposi's sarcoma – association with HHV 8
  • Lymphoma (hard palate; tonsils; intra-bony in mandible and maxilla) – some associated with Epstein Barr virus
  • Salivary gland cystic lymphoepithelial lesion
  • AIDS periodontitis (rapidly progressive); necrotizing ulcerative gingivitis
  • Aphthous-like ulcers
• Treatment:
  • HAART – highly active antiretroviral therapy