凡疮疡之患，所因虽多，其要惟内外二字；证候虽多；其要惟阴阳二字。知此四者，则
尽之矣。然内有由脏者，有由府者，外有在皮肤者，有在筋骨者，此又其浅深之辨也。至其
为病，则无非血气壅滞，营卫稽留之所致。盖凡以郁怒忧思，或淫欲丹毒之逆者，其逆在肝
脾肺肾，此出于脏而为内病之最甚者也。凡以饮食浓味，醇酒炙爆之壅者，其壅在胃，此
出于腑，而为内病之稍次者也。又如以六气之外袭，寒暑之不调，侵入经络，伤人营卫，则
凡寒滞之毒，其来徐，来徐者，其入深，多犯于筋骨之间，此表病之深者也。风热之毒其来
暴，来暴者，其入浅，多犯于皮肤之间，此表病之浅者也。何也。盖在脏在骨者多阴毒，阴
毒其甚也。在腑在肤者多阳毒，阳毒其浅也。所以凡察疮疡者，当识痈疽之辨∶痈者热壅于
外，阳毒之气也，其肿高，其色赤，其痛甚，其皮薄而泽，其脓易化，其口易敛，其来速，
者其愈亦速。此与脏腑无涉，故易治而易愈也。疽者结陷于内，阴毒之气也，其肿不高，其痛
不甚，其色沉黑，或如牛领之皮，其来不骤，其愈最难。或全不知痛痒，甚有疮毒未形，而
精神先困，七恶叠见者，此其毒将发而内先败，大危之候也。知此阴阳内外，则疮痈之概，
可类见矣。然此以外见者言之，但疮疡之发原无定所，或在经络，或在脏腑，无不有阴阳之
辨。若元气强，则正胜邪，正胜邪则毒在腑，在腑者便是阳毒，故易发易收而易治。元气弱
则邪胜正，邪胜正则毒在脏，在脏者便是阴毒，故难起难收而难治。此治之难易，全在虚实
。实者易而虚者难也，速者易而迟者难也。所以凡察痈疽者，当先察元气以辨吉凶，故无论
肿疡溃疡，但觉元气不足，必当先虑其何以收局，而不得不预为之地。万勿见病治病，且顾
目前，则鲜不致害也。其有元气本亏，而邪盛不能容补者，是必败逆之证。其有邪毒炽盛，
而脉证俱实者，但当直攻其毒，则不得误补助邪，所当详辨也。
华元化曰∶痈疽疮肿之作，皆五脏六府蓄毒不流，非独因营卫闭塞而发也。其行也有处
，其主也有归。假令发于喉舌者，心之毒；发于皮毛者肺之毒，发于肌肉者脾之毒，发于骨髓者肾之毒，
发于筋膜者，肝之毒；发于下者，阴中之毒；发
于上者，阳中之毒；发于外者，六腑之毒；发于内者，五脏之毒。故内曰坏，外曰溃，上曰从
，下曰逆。发于上者，得之速；发于下者，得之缓；感于六腑，则易治；感于五脏，则难瘳
。又近骨者多冷，近肤者多热。近骨者，久不愈，则化成血虫。近肤者，久不愈，则传气成
漏。成虫，则多痒少痛，或先痒后痛。成漏，则多痛少痒，或不痒不痛。内虚外实者，多痛
少痒。血不止，则多死。溃脓，则多生。证候多端，要当详治。
伍氏云∶痈疽之疾有二十余证∶曰 发、痼发、石发、岩发、蜂巢发、莲子发、椒眼
发、连珠发、竟体发、肠痈内发、脑背发、眉发、腮颔发、肺痈、瓜瓠发。大率随病浅深内
外施治，不可迟缓。初发如伤寒，脉浮而紧是其候也。
又曰∶五脏六腑俞穴皆在背，凡患疮证，有伤脏膜者多致不救。腑气浮行于表，故痈肿
浮高为易治；脏血沉寒主里，故疽肿内陷为难治。
又曰∶疖者节也，痈者壅也，疽者沮也。一寸至二寸为疖，三寸至五寸为痈，一尺为
疽，一尺至二尺为竟体疽。若脉洪数者难治，脉微涩者易治。初觉，宜清热拔毒。已溃则排
脓止痛。脓尽则长肌敷痂，当酌轻重顺逆而审治之。
马益卿《痈疽论》曰∶人有四肢五脏，一觉一寐，呼吸吐纳，精气往来，流而为营卫，
畅而为气色，发而为声音，阳用其形，阴用其精，此人之常数所同也。至其失也，蒸则生热
，否则生寒，结则为瘤赘，陷则为痈疽，凝则为疮癣，愤则结瘿，怒则结疽。又五脏不和
，则九窍不通，六气不和，则留结为痈，皆经络涩滞，气血不流，风毒乘之而致然也。
薛立斋曰∶疮疡之作，皆由膏梁浓味，醇酒炙爆，房劳过度，七情郁火，阴虚阳辏
，精虚气节，命门火衰，不能生土；营卫虚弱，外邪所袭，气血受伤而为患。当审其经络受
证，标本缓急以治之。
陈良甫曰∶外如麻，里如瓜。又曰，外小如钱，内可容拳。
凡是疮疡的病患，虽然致病原因很多，但关键只在于“内”和“外”这两个字；证候表现虽然繁多，但关键只在于“阴”和“阳”这两个字。明白了这四点，就完全掌握了要领。然而，病邪有源于内脏的，有源于六腑的；病位有在皮肤的，有在筋骨之间的，这是病情深浅的区别。至于其发病机制，无非都是血气壅滞、营卫（运行于脉外与脉内的气血）稽留所致。
大凡因郁怒、忧思，或房事过度、丹毒等逆乱之气影响的，其病逆主要在肝、脾、肺、肾，这些源于五脏，是内病中最严重的。大凡因饮食厚味、醇酒炙烤食物导致的壅塞，其病位在胃，这些源于六腑，是内病中稍轻次的。又如被六淫（风、寒、暑、湿、燥、火六种外感病邪）外袭，寒暑失调，侵入经络，损伤营卫，那么寒滞之毒，其来势缓慢，来势缓慢者，其入里较深，多侵犯筋骨之间，这是表病中较深的。风热之毒，其来势暴急，来势暴急者，其入里较浅，多侵犯皮肤之间，这是表病中较浅的。为什么呢？因为病在脏、在骨的多为阴毒，阴毒病情严重；病在腑、在肤的多为阳毒，阳毒病情较轻浅。
所以，凡是诊察疮疡的人，应当识别痈（一种红肿热痛的化脓性疾病）和疽（一种漫肿无头、皮色不变的坏死性疾病）的区别：痈是热毒壅塞于外部，属于阳毒之气，其肿胀高突，颜色红赤，疼痛剧烈，皮肤薄而有光泽，脓液容易形成，疮口容易愈合，发病迅速，痊愈也迅速。这与脏腑没有直接关系，所以容易治疗且容易痊愈。疽是结聚凹陷于内部，属于阴毒之气，其肿胀不高，疼痛不剧烈，颜色沉黑，或者像牛颈部的皮肤一样坚硬，发病不突然，痊愈最困难。有的完全感觉不到痛痒，甚至有疮毒尚未成形，而精神先已困顿，出现七恶（中医判断疮疡预后的十种危重症状中的七种）叠加显现的情况，这是毒邪将要发作而体内正气先败坏，是非常危险的征象。明白了阴阳内外，疮疡的大概情况就可以类推了。
然而，以上是就外在表现而言的，只是疮疡的发生原本没有固定的部位，有的在经络，有的在脏腑，无不有阴阳的区别。如果元气强盛，则正气战胜邪气，正气战胜邪气则毒邪停留在腑，停留在腑的就是阳毒，所以容易发出、容易收敛且容易治疗。如果元气虚弱，则邪气战胜正气，邪气战胜正气则毒邪停留在脏，停留在脏的就是阴毒，所以难以起发、难以收敛且难以治疗。治疗难易的关键，全在于虚实。实证容易治疗，虚证难治；病程短促的容易治疗，病程迁延的难治。所以凡是诊察痈疽的人，应当先诊察元气以辨别吉凶。因此，无论是肿疡（未溃破的疮疡）还是溃疡（已溃破的疮疡），只要觉得元气不足，必须预先考虑如何收场，不得不提前做好准备。千万不要见病治病，只顾眼前，否则很少不造成危害的。那些元气本来亏损，而邪气盛极不能耐受补益的，是必然败坏的逆证。那些邪毒炽盛，而脉象和证候都表现为实证的，应当直接攻逐毒邪，以免误用补药助长邪气，这一点需要详细辨别。
华元化说：痈疽疮肿的产生，都是五脏六腑蓄积毒邪不得流通，不仅仅是因为营卫闭塞而引发的。其行走有固定的处所，其主治有归属的脏腑。假如发于喉舌的，是心之毒；发于皮毛的，是肺之毒；发于肌肉的，是脾之毒；发于骨髓的，是肾之毒；发于筋膜的，是肝之毒；发于下部的，是阴中之毒；发于上部的，是阳中之毒；发于外部的，是六腑之毒；发于内部的，是五脏之毒。所以在内的称为“坏”，在外的称为“溃”，在上部的称为“从”（顺证），在下部的称为“逆”（逆证）。发于上部的，发病迅速；发于下部的，发病缓慢；感受六腑之毒，则容易治疗；感受五脏之毒，则难以痊愈。又靠近骨骼的多属冷证，靠近皮肤的多属热证。靠近骨骼的，久不愈合，则会化成血虫（指腐肉败血形成的恶物）。靠近皮肤的，久不愈合，则会传变气机形成漏管（瘘管）。形成血虫的，多痒少痛，或者先痒后痛。形成漏管的，多痛少痒，或者不痒不痛。内虚外实的，多痛少痒。出血不止的，大多死亡。溃破流脓的，大多存活。证候多种多样，应当详细治疗。
伍氏说：痈疽的疾病有二十多种证候：包括发、痼发、石发、岩发、蜂巢发、莲子发、椒眼发、连珠发、竟体发、肠痈内发、脑背发、眉发、腮颔发、肺痈、瓜瓠发。大体上根据病情的深浅、内外施治，不可迟缓。初发时如同伤寒，脉象浮而紧是其征候。
又说：五脏六腑的俞穴都在背部，凡是患有疮证，如果有伤及脏膜的多致不治。腑气浮行于体表，所以痈肿浮高易于治疗；脏血沉寒主里，所以疽肿内陷难以治疗。
又说：疖（小的脓肿）就是节的意思，痈就是壅塞的意思，疽就是阻塞的意思。一寸到二寸大小的为疖，三寸到五寸大小的为痈，一尺大小的为疽，一尺到二尺大小的为竟体疽。如果脉象洪大而数的，难治；脉象微细涩滞的，易治。初觉不适时，宜清热拔毒。已经溃破则排脓止痛。脓液排尽则生肌敷痂，应当斟酌病情的轻重、顺逆而审慎治疗。
马益卿《痈疽论》说：人有四肢五脏，有醒有睡，呼吸吐纳，精气往来，流动成为营卫，通畅成为气色，发出来成为声音，阳运用其形体，阴运用其精微，这是人的常数所共同的。至于失和的时候，蒸腾则生热，寒冷则生寒，凝结则为瘤赘，下陷则为痈疽，凝滞则为疮癣，愤懑则结为瘿瘤，愤怒则结为疽。另外五脏不和，则九窍不通，六气不和，则留结为痈，都是经络涩滞，气血不流，风毒乘虚而入而导致的。
薛立斋说：疮疡的产生，都是由膏粱厚味、醇酒炙烤食物、房劳过度、七情郁火、阴虚阳凑、精虚气节、命门火衰不能生土；营卫虚弱，外邪侵袭，气血受伤而患病。应当审察经络受证的状况，根据标本缓急来治疗。
陈良甫说：外表看起来像麻子一样小，里面却像瓜果一样大。又说，外表小如铜钱，里面可以容纳拳头。
Any affliction of sores and ulcers, although caused by various factors, essentially boils down to two characters: "internal" and "external"; although the syndromes are numerous, they essentially boil down to two characters: "Yin" and "Yang". Understanding these four aspects covers everything. However, internally, pathogens may originate from the Zang organs (solid organs) or the Fu organs (hollow organs); externally, lesions may be located in the skin or in the sinews and bones; this distinguishes their depth. As for the pathology, it is invariably caused by the stagnation of Blood and Qi, and the retention of Ying and Wei (nutritive and defensive Qi).
Generally, when caused by depression, anger, worry, or excessive sexual activity and toxic heat, the pathological reversal affects the Liver, Spleen, Lung, and Kidney. These originate from the Zang organs and represent the most severe internal diseases. When caused by rich food, strong wine, and roasted or fried foods leading to obstruction, the pathology resides in the Stomach. These originate from the Fu organs and represent slightly less severe internal diseases. Furthermore, when invaded by the Six Excesses (Wind, Cold, Summer-heat, Dampness, Dryness, Fire) due to improper climate, damaging the Ying and Wei, cold-stagnating toxins arrive slowly; those arriving slowly penetrate deeply, often affecting the sinews and bones, representing deep exterior diseases. Wind-heat toxins arrive violently; those arriving violently penetrate shallowly, often affecting the skin, representing shallow exterior diseases. Why? Because pathologies in the Zang organs and bones are mostly Yin toxins, which are severe; pathologies in the Fu organs and skin are mostly Yang toxins, which are shallow.
Therefore, when examining sores and ulcers, one must distinguish between Carbuncle (a red, swollen, painful suppurative infection) and Gangrenous Ulcer (a dark, indurated, non-suppurative necrosis): Carbuncle is heat obstructing externally, belonging to Yang toxin energy. It presents with high swelling, red color, severe pain, thin and shiny skin, easy suppuration, easy healing, rapid onset, and rapid recovery. It is unrelated to the Zang organs, thus easy to treat and cure. Gangrenous ulcer is nodular and sunken internally, belonging to Yin toxin energy. It presents with low swelling, mild pain, dark/black color, or hard skin like a cow's neck, slow onset, and extreme difficulty in recovery. Some patients feel no pain or itching at all; even before the lesion appears, mental spirit may be exhausted, and the Seven Evil signs (seven critical prognostic indicators in TCM) may appear simultaneously. This indicates that the toxin is about to erupt while the internal righteous Qi has already failed, a critical danger sign. Understanding Yin, Yang, Internal, and External allows one to generalize the nature of sores and carbuncles.
However, this discussion focuses on external manifestations. Sores and ulcers can arise anywhere, in the meridians or in the Zang-Fu organs, always involving a distinction between Yin and Yang. If Yuan Qi (Original Qi) is strong, Righteous Qi overcomes Pathogenic Qi. When Righteous Qi overcomes Pathogenic Qi, the toxin remains in the Fu organs; toxins in the Fu organs are Yang toxins, thus easy to manifest, resolve, and treat. If Yuan Qi is weak, Pathogenic Qi overcomes Righteous Qi. When Pathogenic Qi overcomes Righteous Qi, the toxin remains in the Zang organs; toxins in the Zang organs are Yin toxins, thus difficult to rise, resolve, and treat. The ease or difficulty of treatment depends entirely on Deficiency and Excess. Excess is easy, Deficiency is difficult; rapid progression is easy, slow progression is difficult. Therefore, when examining carbuncles and gangrenous ulcers, one must first assess Yuan Qi to determine auspiciousness or inauspiciousness. Thus, whether it is a pre-ulcerative swelling or an open ulcer, if there is a sense of insufficient Yuan Qi, one must anticipate how to manage the outcome and prepare in advance. One must never merely treat the disease as it appears, focusing only on the present moment, lest harm ensue. Cases where Yuan Qi is inherently deficient but Pathogenic Qi is so excess that tonification cannot be tolerated are inevitably fatal adverse conditions. Cases where Pathogenic toxin is blazing and both pulse and symptoms indicate Excess should be treated by directly attacking the toxin, avoiding the error of using tonics that would aid the pathogen; this requires careful differentiation.
Hua Yuanhua stated: The formation of carbuncles, gangrenous ulcers, and swellings results from the accumulation of toxins in the Five Zang and Six Fu organs that fail to circulate, not merely from the blockage of Ying and Wei. Their movement has specific locations, and their governance has specific organ affiliations. For instance, eruptions on the throat and tongue are toxins of the Heart; eruptions on the skin and hair are toxins of the Lung; eruptions on muscles are toxins of the Spleen; eruptions in bone marrow are toxins of the Kidney; eruptions on tendons and fascia are toxins of the Liver; eruptions below are toxins of the Yin; eruptions above are toxins of the Yang; eruptions outward are toxins of the Six Fu organs; eruptions inward are toxins of the Five Zang organs. Hence, internal lesions are termed "corruption," external lesions "ulceration," upper lesions "compliance" (favorable prognosis), and lower lesions "rebellion" (unfavorable prognosis). Lesions appearing above develop rapidly; those below develop slowly. Infection of the Six Fu organs is easy to treat; infection of the Five Zang organs is difficult to heal. Moreover, lesions near bones are often cold; lesions near skin are often hot. Lesions near bones that do not heal for a long time may transform into "blood worms" (necrotic tissue/biofilm). Lesions near skin that do not heal for a long time may transmit Qi and form fistulas. Formation of blood worms causes more itching than pain, or itching followed by pain. Formation of fistulas causes more pain than itching, or neither. Internal deficiency with external excess causes more pain than itching. Unstoppable bleeding leads to death. Suppuration leads to survival. Syndromes are manifold and require detailed treatment.
Wu Shi stated: There are over twenty types of carbuncle and gangrene syndromes: Fa, Gu Fa, Shi Fa, Yan Fa, Honeycomb Fa, Lotus Seed Fa, Pepper Eye Fa, Beaded Fa, Whole-body Fa, Intestinal Abscess Internal Fa, Brain and Back Fa, Eyebrow Fa, Cheek and Jaw Fa, Lung Abscess, Gourd Fa. Generally, treatment should be applied according to the depth and location of the disease without delay. Initial onset resembles Taiyang disease (Exterior syndrome), with floating and tight pulses being the characteristic signs.
He further stated: The Shu points of the Five Zang and Six Fu organs are all located on the back. Any sore condition that damages the membrane of the Zang organs often proves incurable. Fu Qi floats on the surface, so carbuncles that are floating and high are easy to treat; Zang Blood is heavy and cold, governing the interior, so gangrenous ulcers that are sunken internally are difficult to treat.
He also stated: Jie (small abscess) means joint/nodule; Yong (carbuncle) means obstruction; Ju (gangrenous ulcer) means blockage. Lesions 1 to 2 cun are Jie; 3 to 5 cun are Yong; 1 chi is Ju; 1 to 2 chi are Whole-body Ju. If the pulse is surging and rapid, it is difficult to treat; if the pulse is faint and choppy, it is easy to treat. Upon initial sensation, clear heat and extract toxin. After ulceration, drain pus and relieve pain. When pus is exhausted, promote flesh growth and apply scabs. Treatment should be adjusted based on severity and favorable/unfavorable trends.
Ma Yiqing in *Treatise on Carbuncles and Gangrene* stated: Humans have four limbs and five Zang organs, wakefulness and sleep, respiration, and the circulation of Essence and Qi, which flow to become Ying and Wei, become smooth to form complexion, and emerge as voice. Yang utilizes its form, Yin utilizes its essence; this is common to all humans. When harmony is lost, steaming generates heat, cold generates cold. Condensation forms tumors and protrusions; sinking forms carbuncles and gangrenous ulcers; stagnation forms sores and tinea; frustration forms goiter; anger forms gangrenous ulcers. Furthermore, disharmony of the Five Zang organs leads to blockage of the Nine Orifices; disharmony of the Six Qi leads to retention and condensation forming carbuncles. All result from stagnant meridians and channels, non-flowing Blood and Qi, and wind-toxin taking advantage of the situation.
Xue Lizhai stated: The production of sores and ulcers is caused by rich and greasy food, strong wine, roasted and fried foods, excessive sexual exertion, emotional stagnation transforming into fire, Yin deficiency with Yang aggregation, Essence deficiency with Qi constraint, decline of Mingmen Fire failing to generate Earth (Spleen/Stomach); weakness of Ying and Wei allowing external pathogens to invade, injuring Blood and Qi and causing disease. One must examine the meridians affected and treat according to root and branch, urgency and slackness.
Chen Liangfu stated: Externally resembling hemp seeds, internally resembling melons. He also said: Externally small as a coin, internally large enough to hold a fist.