The patient with an acute maculopapular rash presents a diagnostic challenge to the clinician. The term maculopapular is non-specific, as many eruptions have a primary morphology of macules or papules, and the term may be mis-used to indicate any rash. The term rash is itself also non-specific and is sometimes incorrectly applied to any skin finding; eruption may be preferred for a cutaneous reaction of acute onset. However, the term maculopapular rash is in common clinical usage and will be retained here for purposes of simplicity. Synonyms for maculopapular rash include exanthematous eruption (exanthem) or morbilliform eruption.
The term maculopapular rash typically implies an acute and generalised eruption.
Macule: a flat skin lesion <1 cm in greatest diameter. When macules exceed 1 cm, the appropriate term is patch.
Papule: a raised bump <1 cm in diameter. When papules exceed 1 cm in size, the appropriate term is plaque (palpable lesions elevated above the skin surface) or nodule (a larger, firm papule with a significant vertical dimension).
Other morphological terms encountered in this clinical setting include:
Pustule: a papule containing purulent fluid
Vesicle: a papule containing clear serous fluid
Bulla: a larger vesicle >1 cm
Urticaria: a wheal or hive.
Hence, the term maculopapular rash implies a skin eruption of flat and raised lesions.
Professor & Director of Pediatric Dermatology
Department of Dermatology and Pediatrics
UTHealth McGovern Medical School Houston
AAH declares that she has no competing interests
Clinical Research Fellow
Department of Dermatology
University of Texas Health Sciences Center in Houston
MD declares that she has no competing interests.
Dr Adelaide A. Hebert and Dr Mary DarConte would like to gratefully acknowledge Dr Mark Naftanel and Dr Hobart W. Walling, previous contributors to this topic. MN and HWW declare that they have no competing interests.
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