Diaper Rash Workup

Updated: Nov 09, 2018
  • Author: Rania Dib, MD; Chief Editor: Kirsten A Bechtel, MD  more...
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Laboratory Studies

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  • The primary forms of diaper rash generally can be diagnosed clinically. Laboratory studies have few indications and limited utility.

  • A complete blood count may be helpful, especially if a fever is present and a secondary bacterial infection is suspected.

  • The finding of anemia in association with hepatosplenomegaly and the appropriate rash may suggest a diagnosis of Langerhans cell histiocytosis or congenital syphilis.

    • When suspecting congenital syphilis, relevant serology should be sent.

    • Dark field microscopic examination for spirochetes from any bullous lesion scrapings can be performed.

  • Serum zinc level of less than 50 mcg/dL can confirm acrodermatitis enteropathica.

  • Gram stain or culture of the characteristic bullae of impetigo for S aureus can confirm this diagnosis.

  • Routine cultures demonstrate polymicrobial infections (eg, streptococci, Enterobacteriaceae, and anaerobes) in nearly one half of cases.


Other Tests

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  • Potassium hydroxide (KOH) scrapings from a fresh papular or pustular lesion may demonstrate pseudohyphae in suspected cases of candidiasis. However, these may be absent in long-standing cases.

  • Finding mites, ova, or feces on a mineral oil preparation of a burrow scraping can confirm the diagnosis of scabies.



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  • Skin biopsy can be performed to help differentiate granuloma gluteale infantum from granulomatous and neoplastic processes.

    • Histopathology, granuloma gluteale presents as nonspecific dermal inflammatory infiltrate composed of neutrophils, lymphocytes, histiocytes, plasma cells, occasional giant cells, and eosinophils, sometimes with an increase in the number of capillaries.

    • Examination of granuloma gluteale using an electron microscope reveals 3 types of giant cells: in the first type, the cells have widely enlarged endoplasmic reticulum; in the second type, they phagocytize erythrocytes; and in the third type, they have vesicles and granules and are similar to histiocytes. The name granuloma gluteale infantum is a misnomer since no granulomas are found in these lesions.

    • Skin biopsy also is used to confirm the diagnosis of Langerhans cell histiocytosis.