Clinical Features:

• Caused by viral reactivation in patients previously infected by varicella zoster virus (VZV)
• Painful vesicles on an erythematous base in the distribution of a sensory dermatome
• Most often seen in elderly and immunocompromised individuals
• Immunocompromised patients are at risk for disseminated infection.

Histologic Features:

• The changes are identical to those seen in varicella and herpes simplex:
  • "Steel gray" keratinocyte nuclei
  • Multinucleated keratinocytes with margination of chromatin ("pomegranates")
  • Eosinophilic nuclear inclusions surrounded by clear haloes
  • Intracellular edema and ballooning degeneration
  • Acantholysis
  • Intraepidermal vesiculation
  • Dense dermal lymphocytic inflammation
  • Sometimes inflammation of nerve twigs and/or vasculitis is seen.
• Immunocompromised patients may have marked necrosis of the epidermis and widespread involvement of adnexal structures.

Herpes zoster folliculitis:

Clinical Features:

• Herpes simplex and herpes zoster virus do not typically involve the hair follicles, but may occasionally do so, particularly in early infection.
• Lesions may be especially widespread and severe in immunocompromised patients.

Histologic Features:

• Viral cytopathic effects may be seen within the hair follicles: dysmaturation, acantholysis, dyskeratosis, multinucleate keratinocytes.
• There may be focal to extensive necrosis of the hair follicle.
• The dermis shows dense perivascular and sometimes perineural lymphocytic infiltrates, in some cases with atypia that may mimic lymphoma.

Cases associated with this book:

Herpes zoster folliculitis
Author: Artur Zembowicz M.D. Ph.D.

Conference: DermatopathologyConsultations.com Teaching Collection