When devising morphological descriptions, it would seem that dermatologists in years gone by had their heads in the clouds, with several descriptions alluding to phenomena related to the weather.
During the Buerger test, the reactive hyperemia observed in patients with peripheral vascular disease is often described as a “sunset red.” The vesicles of cutaneous anthrax are often described as “cloudy,” as is the saliva of patients with Sjögren disease. Miliaria crystallina have been likened to dew drops, and the classical description of varicella zoster is that of “dew drops on rose petals.” The distribution and morphologic characteristics of guttate psoriasis have been likened to raindrops, and the dyschromia of chronic arsenic toxicity has been more vividly compared to “rain drops on a dusty road.” Dermoscopic examination of Kaposi sarcomas may sometimes reveal a multicolored rainbow,1 livedo racemosa has been compared to bolts of lightning, and perhaps one of the most fascinating clinical signs in dermatology is the Lichtenberg figures that appear on patients who have been struck by lightning.
Sebaratnam DF, Minocha R, Fernández-Peñas P. Dermatology Over the Rainbow. JAMA Dermatol. 2015;151(5):543. doi:10.1001/jamadermatol.2014.5351