The etiological diagnosis of exanthems can be challenging for dermatologists. Rash morphology, related symptoms, and the presence of enanthems provide diagnostic clues. It was reported that pustular morphology and dusky lesions are suggestive of drug etiology. On the other hand, petechial or vesicular pattern, the involvement of buttocks or acral sites, and enanthem are suggestive of an infectious etiology, particularly viral.

Enanthems may manifest as petechiae, macules, papules, or vesicles in the mouth. Erythemato-vesicular and petechial patterns were frequently linked with viral infections, more so in adults. In a study on COVID-19 patients, the same has been seen where almost 83% of patients have petechiae as a significant part of the enanthem. Besides, a couple of patients with a pure petechial enanthem developed the lesions two days before and two days after the onset of COVID-19 symptoms, making an association with the drug use improbable.

Reference: Jimenez-Cauhe J, et al. enanthem in patients with COVID-19 and skin rashes. JAMA Dermatol. 2020; 156 (10): 1134-1136. DOI: 10.1001/jamadermatol.2020.2550