Which test is used to detect herpetic lesions?

The Tzanck smear is specifically utilized to detect herpetic lesions, particularly in cases of suspected herpes simplex virus. This test involves taking a sample from the base of a vesicular lesion and examining it microscopically. The presence of multinucleated giant cells typically indicates a herpes infection, as this is a characteristic finding associated with the virus.

In contrast, other options such as a CT scan and X-ray are imaging techniques, primarily used for assessing structural changes or abnormalities in bodily tissues rather than for directly identifying viral infections like herpes. A biopsy, while it can provide more definitive histological information, is generally not the first-line test for herpes simplex virus and is more invasive, typically reserved for cases where there's uncertainty or suspicion of malignancy. Therefore, the utility of the Tzanck smear for rapid identification of herpetic lesions makes it the appropriate choice.