Various pains, itching, and sores/ulcers (chuang yang) all belong to Heart Fire. Therefore, diseases of sores and ulcers are not caused by external pathogens directly. In the past, people classified them as surgical conditions because their morphology and symptoms manifest on the exterior, unlike internal medicine conditions which are hidden within. Among sores and ulcers, carbuncles (yong) and gangrenous sores (ju) are the most severe, while the toxicity of large ding-sores (ding) is even more severe than that of carbuncles and gangrenous sores. Thus, when treating large ding-sores, only one or two out of ten survive; when treating gangrenous sores, five or six out of ten survive; and when treating carbuncles, eight or nine out of ten survive. This is merely due to the depth of toxicity, which determines the difficulty of treatment. However, how can one distinguish between carbuncles, gangrenous sores, and large ding-sores? One should only observe the height of swelling, the extent of the lesion, and the floating or sunken nature of the pulse.

The term "carbuncle" (yong) implies obstruction. Qi and Blood are obstructed and stasis-forming due to toxicity, failing to circulate, thus manifesting as a carbuncle. At the initial stage, there must be aversion to cold (saxi ehan) and slight fever. Carbuncles often occur on the back and crown. Those occurring on the upper back, either on the left or right, are called "Upper Hand-Clasping" (Shang Dashou); those on the lower back are sometimes called "Central Eruption" (Zheng Fa); those occurring at the back of the head are called "Opposite Mouth" (Dui Kou). Compared to the Upper Hand-Clasping, these have greater toxicity. Generally, carbuncles present with redness, heat, and high swelling, tend to expand rapidly, but have shallow roots, belonging to Yang syndromes.

The term "gangrenous sore" (ju) implies blockage. Qi and Blood are blocked by toxicity and fail to circulate, thus manifesting as a gangrenous sore. At the initial stage, there is also aversion to cold, preceded by numbness and itching, resembling the sensation of ants crawling. Palpation reveals hardness inside, and it cannot be moved by pushing. Gangrenous sores frequently occur between the back, waist, shoulders, and buttocks, as well as in the lower abdomen and sides of the chest. Those occurring between the thighs and feet are named "Bone-Attaching Gangrene" (Fugu Ju). Generally, gangrenous sores do not swell highly, do not expand easily, but have deep roots. Only those occurring on the center of the back and thighs are extremely severe, originating from the Five Zang Organs, belonging to Yin syndromes.

The term "ding-sore" (ding) resembles the character "Ding" (a nail-like shape), like a nail driven into wood, impossible to pull out or shake loose. Its root is extremely deep, its toxicity extreme, and its head very hard. At the initial stage, there is no pain or itching, only numbness. Externally it may look like common skin eruptions, but internally it is profound. When the condition becomes severe, the pain is excruciating, causing heart palpitations and胆 fear, unbearable. This is fire-toxicity generated from the Five Zang and Six Fu Organs, simmered for a long time and converging in one place to form a ding-sore. Ding-sores are mostly seen between the facial bones and joints. Investigating the source of this toxicity, it often arises from improper diet and medication. The Classic states: "Changes from rich and greasy foods can produce large ding-sores." Foods that are fatty, sweet, strong-flavored, roasted, fried, or boiled can best assist fire. People who indulge in flavors, overeat, drink excessively, and engage in sexual excess cause the Spleen Earth to become dry and hot, and Kidney Water to become depleted. After accumulation over time, the toxin remains in the Five Zang Organs and spreads through the Six Fu Organs. Fire stagnates and does not disperse, taking advantage of areas where Qi and Blood are deficient to erupt. The root is internal, while agitation and blazing occur externally. Its toxicity is worse than that of poisonous birds; if its flesh were cut and fed to chickens or dogs, they would die immediately. This is why large ding-sores often result in death. As for conditions that resemble ding-sores but are not, they can all be treated as general toxic swellings without major harm.

How then to distinguish the pulses of these three? A pulse that is floating and rapid indicates toxicity in the exterior, thus identifying it as a carbuncle. A pulse that is sunken and rapid indicates toxicity in the interior, thus identifying it as a gangrenous sore. If the pulse is sunken and slippery, rapid and wiry-tight, it must be a ding-sore. These are visible manifestations. Although treatment varies in difficulty, one can still apply therapy based on symptoms. However, conditions such as intestinal carbuncle, abdominal carbuncle, and pulmonary carbuncle belong to internal carbuncles. Their presentation is indistinguishable from masses and accumulations (zheng jia pi pi). If mistakenly treated as internal medicine conditions using herbs that break hardness and dissipate nodules, the treatment will be inappropriate, and life will soon be lost.

The general principle for treating external sores and ulcers is that at the initial stage, moxibustion is preferable. Once the smoke of moxa penetrates, the toxicity is immediately effective. If delayed until the sixth or seventh day, moxibustion should not be used. For superficial toxicity, use puncturing methods (e.g., topical application); for deep toxicity, use incision to drain; for toxicity particularly deep beyond the reach of needles and knives, use cauterization. Before pus forms, use detoxification methods; after pus forms, use methods to support the interior and promote drainage. This represents the clinical adaptability of the physician.