ויקרא, פרק י״ג, פסוק כ׳

The diagnosis of leprosy becomes particularly complex when it appears over a previously existing, healing wound. The priest must evaluate specific visual signs, such as the depth of the mark, its color, and its effect on the hair within it, to determine if the healing injury has transformed into a source of impurity. When examining the mark, the priest looks to see if it appears lower than the surrounding skin. The primary approach among commentators is that the spot is not physically sunken in a way that can be felt by touch. Instead, it is an optical illusion. The intense whiteness of the mark makes it look deeper than the area around it, just as bright sunlight can appear deeper than a shadow. The emphasis is entirely on how the spot looks to the eye [רש״י, משכיל לדוד].

The visual description notes that the mark appears low, whereas other instances describe the disease as deep. One approach explains that a deep mark represents a more profound depression than a low one. Because the mark over a healing wound has a mixed color of white and red, it naturally appears less sunken than a spot that is completely pure white [ביאור יש״ר, העמק דבר, פירושי רד צ הופמן]. Another perspective suggests that a deep spot is sunken on all sides, like a pit, while a low spot describes a depression on just one side, like a valley alongside a mountain. In a mixed spot, the white section looks sunken while the red section appears raised [פירושי רד צ הופמן]. Regardless of these nuances, this description of depth applies specifically to a bright white spot, rather than a raised swelling [רלב״ג, העמק דבר, פירושי רד צ הופמן].

Despite these visual descriptions, the mark is not legally required to appear sunken. Even if it is level with the skin or slightly raised, it is still deemed impure as long as the definitive sign of impurity is present [תורה תמימה, מלבי״ם, חזקוני]. This critical sign occurs when the hair inside the mark turns white [תורה תמימה, ביאור שטיינזלץ]. The change in hair color is a physical symptom of abnormal body heat and internal decay [רלב״ג].

This internal decay is unable to escape the body except through its weakest point, which in this case is the healing wound [רלב״ג, ביאור שטיינזלץ]. While the term used for the disease breaking out typically refers to the blooming of flowers, in the context of skin afflictions, it describes the spreading and expanding of the disease [מלבי״ם, אילת השחר]. However, the diagnosis remains strictly confined to this specific location. The leprosy is evaluated entirely within the borders of the original wound and does not combine with or spread to healthy skin or an area of a burn [תורה תמימה, אדרת אליהו, רש ר הירש].