Atopic Dermatitis Workup

Updated: Feb 13, 2023
  • Author: Brian S Kim, MD, MTR, FAAD; Chief Editor: William D James, MD  more...
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Laboratory Studies

No biomarker for the diagnosis of atopic dermatitis (AD) is known. Laboratory testing is seldom necessary.

A swab of infected skin may help with the isolation of a specific organism (eg, Staphylococcus or Streptococcus) and antibiotic sensitivity. Allergy and radioallergosorbent testing is of little value.

A swab for viral polymerase chain reaction (PCR) may help identify superinfection with herpes simplex virus and identify a diagnosis of eczema herpeticum.

A complete blood cell count for thrombocytopenia helps exclude Wiskott-Aldrich syndrome, and testing to rule out other immunodeficiencies may be helpful. This also helps identify peripheral eosinophilia, which may help to support the diagnosis.

A serum IgE level can be helpful to support the diagnosis.

Scraping to exclude tinea corporis is occasionally helpful.


Histologic Findings

Biopsy shows characteristic acute, subacute, or chronic spongiotic dermatitis, but findings are not specific.