A soldier is experiencing an itchy rash with vesicles and swelling. What is the likely cause?

The scenario describes a soldier with an itchy rash characterized by vesicles (small fluid-filled blisters) and swelling. The most likely cause of such symptoms is contact dermatitis. This condition arises when the skin comes into direct contact with an irritant or an allergen, leading to an inflammatory response.

In cases of contact dermatitis, the symptoms can include redness, itching, swelling, and the formation of vesicles, particularly when the response is acute. Common irritants could be substances like certain types of soap, chemicals, or even plants (such as poison ivy), while allergens might include specific metals or fragrances. The nature and recent exposure to any potential irritants or allergens would be vital in confirming this diagnosis.

While an allergic reaction might seem relevant, it is broader in definition and can present differently. Infection generally involves systemic symptoms such as fever and tenderness, and psoriasis typically features well-defined patches of redness with silvery scales, rather than the vesicular presentation described. Thus, contact dermatitis aligns closely with the symptoms observed, making it the most appropriate answer in this scenario.