Skin inflammatory (nontumor)
Spongiotic, psoriasiform and pustular reaction patterns
Acute generalized exanthematous pustulosis

Senior Author: Joshua Wisell, M.D.
Editor-in-Chief: Debra Zynger, M.D.

Topic Completed: 13 March 2019

Revised: 13 March 2019

Copyright: 2019, PathologyOutlines.com, Inc.

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Cite this page: Vaughan VC, Wisell J. Acute generalized exanthematous pustulosis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumoragep.html. Accessed March 20th, 2019.
Definition / general
  • Pustular drug eruption
  • May have superficial desquamation
Essential features
  • Pustular drug eruption
  • Most commonly associated with beta lactams and macrolides but also calcium channel blockers, acetaminophen, nonsteroidal anti-inflammatory drugs, proton pump inhibitors, anticonvulsants (carbamazepine), cetirizine, antimalarials, antifungals and more rarely, enterovirus or mercury exposure (Int J Dermatol 2017;56:405)
  • Short interval from exposure to eruption, < 4 days
  • Quick improvement after withdrawal of offending agent
Terminology
  • Acute generalized exanthematous pustulosis, AGEP, toxic pustuloderma
ICD coding
  • ICD-10: L27.0 - Generalized skin eruption due to drugs taken internally
Epidemiology
Pathophysiology
Diagrams / tables

Images hosted on other servers:

Proposed mechanism

Etiology

Clinical features
  • Acute onset of nonfollicular based monomorphic sterile pustules on a background of edematous erythema with superficial desquamation in areas of confluence (J Am Acad Dermatol 2015;73:843)
  • Spreads from the face and intertriginous areas
  • Mucous membrane involvement may occur
  • Fever, pruritus or burning sensation
  • Resolves in 1 - 2 weeks
  • 17% of cases have visceral involvement
  • 1 - 2% mortality
Diagnosis
  • Histological findings are nonspecific and a definitive diagnosis should only be rendered in the appropriate clinical context and after consideration of other entities with the same histological appearance
  • Eruption should occur shortly after initiation of a new drug or, less commonly, with viral infection and should also convalesce after discontinuation of the drug
  • Patch testing can be useful in confirming the patient's sensitivity to the drug in question
Laboratory
  • Neutrophilia and leukocytosis
  • Abnormal renal function and hepatic function tests may occur
  • Immunofluorescence is negative (as opposed to IgA pemphigus and pemphigus foliaceus)
  • 50 - 60% of cases have a positive patch test to offending agent
Case reports
Treatment
  • Discontinue drug (J Immunol Res 2017;2017:1503709)
  • Topical or systemic steroids (cautiously as steroids may provoke a pustular psoriasis flare)
  • May pursue patch testing, especially in cases in which multiple drugs are suspected
Clinical images

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Erythematous macules

Vesicles and desquamation

Sterile
micropustules
on a background
of macular erythema

Pruritic nonfollicular
based pustules
over edematous
erythema


Facial edema

Pustules occur in intertriginous areas such as the axilla

Eruption resolves with superficial desquamation

Microscopic (histologic) description
  • Subcorneal pustules
  • Spongiosis
  • Histologically similar to pustular psoriasis but may have rare dermal eosinophils
  • Scattered epidermal neutrophils
  • Papillary dermal edema
  • Perivascular mixed infiltrate, often with eosinophils and neutrophils
  • Necrotic keratinocytes are sometimes seen
Microscopic (histologic) images

Contributed by University of Colorado Department of Pathology

Subcorneal neutrophilic pustules, spongiosis, scattered dermal eosinophils



Contributed by Joshua Wisell, M.D.

Superficial epidermal pustulation, spongiosis, scattered dermal eosinophils

Immunofluorescence description
  • Negative
Negative stains
  • Special stains may be used to exclude mimickers (e.g. a Gram stain may be used to investigate the possibility of bullous impetigo)
Differential diagnosis
Board review question #1
A skin biopsy is received from a patient staying in the intensive care unit and undergoing antimicrobial therapy for bacterial pneumonia. On physical exam, there are innumerable minute monomorphic pustules over the trunk on a background of intense erythema with desquamation in the skin folds. The biopsy shows subcorneal clefting with neutrophilic pustules, spongiosis and scattered dermal eosinophils. Which of the following is most likely given the biopsy and clinical context?

  1. Acute generalized exanthematous pustulosis
  2. Cellulitis
  3. Folliculitis
  4. Sneddon-Wilkinson disease
  5. Staphylococcal scalded skin disease
Board review answer #1
A. Acute generalized exanthematous pustulosis

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Board review question #2
The following skin biopsy is taken from the trunk of a 50 year old man. Which of the following is the most likely diagnosis?



  1. Acute generalized exanthematous pustulosis
  2. Bullous pemphigoid
  3. Eczema
  4. Pemphigus vulgaris
  5. Sweet syndrome
Board review answer #2
A. Acute generalized exanthematous pustulosis

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