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This type of *ju* sore (ulcerative lesion) is not the typical *yong ju* (carbuncle and furuncle), but belongs to the category of *gan* sores (gangrenous or parasitic ulcers), commonly known in the world as *gan ju*. It frequently occurs between the fingers, toes, and the shins, often appearing symmetrically. It presents as small, scrofula-like nodules with numerous tiny pores on the surface. There are insects within the sore causing itching and pain; scratching yields yellow exudate. The condition heals temporarily but recurs repeatedly.

Cold and heat pathogenic factors invade the meridians, causing stagnation and obstruction of Qi and Blood. Initially, small scrofula-like nodules form, varying in size from that of a plum or apricot pit to a dried fruit. They may be round or elongated, with elongated ones reaching five or six *fen* (approx. 1.6-2 cm), but not exceeding one *cun* (approx. 3.3 cm). They may appear singly or in clusters of two or three. Accompanied by alternating chills and fever, and persistent discharge of pus and blood, this condition is termed "Lou" (fistula/sinus tract). These conditions arise from disharmony among the Zang-Fu organs, leading to deficiency of Qi and Blood, which makes the body susceptible to cold and heat pathogens. Regarding the term "Gan," it refers to conditions such as Shu Lou (scrofula), Lou Gu Ju (mole cricket ulcer), Qiu Yin Chuang (earthworm sore), and Si Cao Chuang (white grub sore); these are discussed in detail in the sections concerning disease names.

The condition referred to as "Xuan" (tinea/ringworm) is formed by the struggle between Wind-Dampness and Qi and Blood. It mostly occurs around the joints and wrists of the hands and feet, presenting densely. Scratching causes itching and pain, and the lesions spread gradually through infiltration. It is called Xuan because there are fine insects in the sores, resembling centipedes (You Yan).

Jie Chuang (Scabies) mostly arises between the fingers and toes, spreading gradually to the rest of the body, accompanied by itching and purulent discharge. According to the *Jiu Chong Lun* (Treatise on Nine Parasites), *Nao Chong* (pinworms/Ascaris) can undergo various transformations and also manifest as Scabies. The sores contain fine parasites that are difficult to see. Infants often contract this disease from caregivers who have scabies.

Xuan Bing (Tinea disease) results from Wind Pathogen struggling with Qi and Blood in the skin, failing to dissipate, thereby generating hidden rashes (Yin Zhen). On these rashes, lesions appear grain-sized like millet seeds, forming distinct borders (Kuang Guo), either irregular or round. They spread via infiltration, causing itching and pain, with exudate upon scratching, and are named Xuan.
Xian Er Mian Shang Xuan (Infant Facial Tinea): The skin becomes rough like scales, dry, and is called Ru Xuan (Milk Tinea). This occurs because milk residue stains the infant's face during feeding, leading to its formation. Washing the area with breast milk leads to recovery.

In infants, if Qi and Blood are disharmonious, red patches may develop on the muscles. These patches spread gradually without a fixed shape, sometimes the size of a coin, or several inches wide.

Qi Chuang (Umbilical Sore): This arises because after cutting the umbilical cord at birth, the area was not dried immediately after bathing, allowing dampness to remain in the navel. When the cord detached, exposure to Wind occurred. The combination of Wind and Dampness caused the umbilical sore to fail to heal for a long time. If the umbilical sore does not heal, Wind Pathogen enters and damages the meridians, potentially transforming into Epilepsy (Xian Zheng).