Pustular Psoriasis Workup

Updated: Oct 08, 2021
  • Author: Clay J Cockerell, MD; Chief Editor: William D James, MD  more...
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Laboratory Studies

Findings include the following:

  • Complete blood cell (CBC) count with absolute lymphopenia coinciding with polymorphonuclear leukocytosis up to 40,000/µL
  • Elevated erythrocyte sedimentation rate (ESR)
  • Elevated C-reactive protein (CRP) [1]
  • Serum chemistries - Increased plasma globulins; decreased albumin, calcium, and zinc; elevated BUN and creatinine if the patient is oligemic; elevated liver enzymes (aspartate transaminase [AST], alanine transaminase [ALT]) if liver damage has occurred
  • Urinalysis - Positive albumin; positive casts
  • Bacterial cultures and sensitivities of pustules - Negative in the absence of secondary infection, as are Tzanck preparations and viral cultures; loss of the cutaneous barrier may result in bacteremia

Histologic Findings

The overall architecture of the epidermis is similar to patients with psoriasis vulgaris, exhibiting parakeratosis, elongation of rete ridges, and thinning of the suprapapillary epidermis. The superficial dermis shows a mononuclear infiltrate and numerous neutrophils migrating from papillary capillaries to the epidermis. Neutrophils in the epidermis can aggregate between keratinocytes, where there is also spongiosis, forming pustules known as spongiform pustules of Kogoj, a characteristic histologic feature. [28]