|A malar rash, or "butterfly rash," is characteristically red or purplish and mildly scaly (seen in patients with systemic lupus erythematosus).|
A malar rash (from Latin mala ‘jaw, cheek-bone’), also called butterfly rash, is a medical sign consisting of a characteristic form of facial rash. It is often seen in lupus erythematosus but is not pathognomonic - it is also seen in other diseases such as pellagra, dermatomyositis, and Bloom syndrome. While some literature has described the slapped-cheek rash of fifth disease as a malar rash, it differs slightly in that the nose is typically spared. 
The malar rash of lupus is red or purplish and mildly scaly. Characteristically, it has the shape of a butterfly and involves the bridge of the nose. Notably, the rash spares the nasolabial folds of the face, which contributes to its characteristic appearance. It is usually macular with sharp edges and not itchy. The rash can be transient or progressive with involvement of other parts of the facial skin.
There are numerous other conditions which can cause rashes with a similar appearance. Where lupus is suspected, further medical tests (usually an ANA as a screening test which is not specific for systemic lupus erythematosus) and a detailed history and examination are necessary to differentiate it from other conditions.
- Cooray, Mohan; Manolakos, Joshua; Wright, Douglas; Haider, Sharig; Patel, Ameen (15 Oct 2013). "Parvovirus infection mimicking systemic lupus erythematosus". CMAJ. 185 (15): 1342–1344. doi:10.1503/cmaj.121565. PMC 3796600. PMID 23979870.
- Houman, M H; Smiti-Khanfir, M; Ghorbell, I B.; Miled, M (2004). "Systemic lupus erythematosus in Tunisia: demographic and clinical analysis of 100 patients". Lupus. 13 (3): 204–11. doi:10.1191/0961203303lu530xx. PMID 15119551.
- Vila, L. M.; Alarcón, G. S.; McGwin, G.; Friedman, A. W.; Baethge, B. A.; Bastian, H. M.; Fessler, B. J.; Reveille, J. D. (2004). "Early clinical manifestations, disease activity and damage of systemic lupus erythematosus among two distinct US Hispanic subpopulations". Rheumatology. 43 (3): 358–63. doi:10.1093/rheumatology/keh048. PMID 14623949.