The term morbilliform refers to a rash that looks like

measles Measles is a highly contagious infectious disease caused by measles virus. Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days. Initial symptoms typically include fever, often greater than , cough, ...

. The rash consists of macular lesions that are red and usually 2–10 mm in diameter but may be confluent in places. A morbilliform rash is a rose-red flat ( macular) or slightly elevated ( maculopapular) eruption, showing circular or elliptical lesions varying in diameter from 1 to 3 mm, with healthy-looking skin intervening. Patients with measles will have the rash but there are other syndromes and infections that will display the same symptom such as patients with Kawasaki disease, meningococcal

petechiae A petechia () is a small red or purple spot (≤4 mm in diameter) that can appear on the skin, conjunctiva, retina, and mucous membranes which is caused by haemorrhage of capillaries. The word is derived from Italian , 'freckle,' of obscure origin ...

or Waterhouse-Friderichsen syndrome, Dengue, Roseola, congenital syphilis,American Family Physician Sept 1st 2012 Vol 86 No 5 pp381-482 Syphilis: A re-emerging infection.

rubella Rubella, also known as German measles or three-day measles, is an infection caused by the rubella virus. This disease is often mild, with half of people not realizing that they are infected. A rash may start around two weeks after exposure and ...

, Echovirus 9,thefreedictionary.com > morbilliform rash
Retrieved on Nov 30, 2009 drug hypersensitivity reactions (in particular with certain classes of antiretroviral drugs, such as

abacavir Abacavir, sold under the brand name Ziagen among others, is a medication used to treat HIV/AIDS. Similar to other nucleoside analog reverse-transcriptase inhibitors (NRTIs), abacavir is used together with other HIV medications, and is not recom ...

and nevirapine, and also the antiepileptic drug phenytoin), or other conditions may also have a morbilliform rash. It has also been mentioned as a possible manifestation of onset or recovery from COVID-19. One cause of morbilliform rash is an allergic reaction to transfused blood/blood components. In such a case, the skin lesions would develop within a few hours (Approx. 4hours) of transfusion along with pruritus. The condition may even present with other symptoms, such as conjunctival oedema, oedema in the lips and tongue, and even localised angioedema. On rare occasions, the condition may even escalate to anaphylactic shock where pulmonary restrictions are seen. The associated cause for this is a reaction against an allergen that is seldom identified during testing. Transfusing products with anti-IgA antibodies to IgA-deficient patients has also been a suspected cause for such reactions. Management usually relates to the stoppage of transfusion for around 30minutes, until given antihistamines take effect. Transfusion may even be continued after, if no further progression is seen.

References

Dermatologic terminology Pediatrics Measles {{dermatology-stub