Tuberculous gumma (also known as a "metastatic tuberculous abscess" and "metastatic tuberculous ulcer") is a cutaneous condition characterized histologically by massive necrosis. Restated, this is a skin condition that results from hematogenous dissemination of mycobacteria from a primary focus, resulting in firm, nontender erythematous nodules that soften, ulcerate, and form sinuses.

Primary inoculation tuberculosis (also known as "Cutaneous primary complex," "Primary tuberculous complex," and "Tuberculous chancre") is a skin condition that develops at the site of inoculation of tubercle bacilli into a tuberculosis-free individual.

Because the TVC's entry point usually is the site of a trauma, wound or puncture in the skin (during an autopsy, for example), the most frequent site for the wart are the hands. But it can occur anywhere in the skin, such as in the sole of the feet, in the anus, and, in the case of children from developing countries, in the buttocks and knees. This is because children from countries of high incidence of tuberculosis can contract the lesion after contact with tuberculous sputum, by walking barefoot, sitting or playing on the ground.

When recent, the skin lesion has the outside appearance of a wart or verruca, thus it can be confused with other kinds of warts. It evolves to an annular red-brown plaque with time, with central healing and gradual expansion in the periphery. In this phase, it can be confused with fungal infections such as blastomycosis and chromoblastomycosis.

Tuberculous lymphadenitis (or tuberculous adenitis) is a chronic specific granulomatous inflammation of the lymph node with caseation necrosis, caused by infection with "Mycobacterium tuberculosis" or "Mycobacterium bovis".

The characteristic morphological element is the tuberculous granuloma (caseating tubercule). This consists of giant multinucleated cells and (Langhans cells), surrounded by epithelioid cells aggregates, T cell lymphocytes and fibroblasts. Granulomatous tubercules eventually develop central caseous necrosis and tend to become confluent, replacing the lymphoid tissue.

Stages of tubercular lymphadenitis:

1. Lymphadenitis

2. Periadenitis

3. Cold abscess

4. 'Collar stud' abscess

5. Sinus

Tuberculous lymphadenitis is popularly known as collar stud abscess, due to its proximity to the collar bone and superficial resemblance to a collar stud, although this is just one of the five stages of the disease. The characteristic morphological element is the tuberculous granuloma (caseating tubercule): giant multinucleated cells (Langhans cells), surrounded by epithelioid cells aggregates, T cell lymphocytes and few fibroblasts. Granulomatous tubercules evolve to central caseous necrosis and tend to become confluent, replacing the lymphoid tissue.

Miliary tuberculosis is a form of tuberculosis that is characterized by a wide dissemination into the human body and by the tiny size of the lesions (1–5 mm). Its name comes from a distinctive pattern seen on a chest radiograph of many tiny spots distributed throughout the lung fields with the appearance similar to millet seeds—thus the term "miliary" tuberculosis. Miliary TB may infect any number of organs, including the lungs, liver, and spleen. Miliary tuberculosis is present in about 2% of all reported cases of tuberculosis and accounts for up to 20% of all extra-pulmonary tuberculosis cases.

Tuberculous cellulitis is a skin condition resulting from infection with mycobacterium, and presenting as cellulitis.

Tuberculosis verrucosa cutis (also known as "lupus verrucosus", "prosector's wart", and "warty tuberculosis") is a rash of small, red papular nodules in the skin that may appear 2–4 weeks after inoculation by "Mycobacterium tuberculosis" in a previously infected and immunocompetent individual.

It is so called because it was a common occupational disease of prosectors, the preparers of dissections and autopsies. Reinfection by tuberculosis via the skin, therefore, can result from accidental exposure to human tuberculous tissue in physicians, pathologists and laboratory workers; or to tissues of other infected animals, in veterinarians, butchers, etc. Other names given to this form of skin tuberculosis are anatomist's wart and verruca necrogenica (literally, generated by corpses).

TVC is one of the many forms of cutaneous tuberculosis, such as the tuberculous chancre (which results from the inoculation in people without immunity), and the reactivation cutaneous tuberculosis (the most common form, which appears in previously infected patients). Other forms of cutaneous tuberculosis are: lupus vulgaris, scrofuloderma, lichen scrofulosorum, erythema induratum and the papulonecrotic tuberculid.

It was described by René Laennec in 1826.

Scrofuloderma (also known as "Tuberculosis cutis colliquativa") is a skin condition caused by tuberculous involvement of the skin by direct extension, usually from underlying tuberculous lymphadenitis.

Patients with miliary tuberculosis often experience non-specific signs, such as coughing and enlarged lymph nodes. Miliary tuberculosis can also present with enlarged liver (40% of cases), enlarged spleen (15%), inflammation of the pancreas (<5%), and multiple organ dysfunction with adrenal insufficiency (adrenal glands do not produce enough steroid hormones to regulate organ function). Miliary tuberculosis may also present with unilateral or bilateral pneumothorax rarely. Stool may also be diarrheal in nature and appearance.

Other symptoms include fever, hypercalcemia, chorodial tubercles and cutaneous lesions.

Firstly, many patients can experience a fever lasting several weeks with daily spikes in morning temperatures.

Secondly, hypercalcemia prevails in 16 to 51% of tuberculosis cases. It is thought that hypercalcemia occurs as a response to increased macrophage activity in the body. Such that, 1,25 dihydroxycholecalciferol (also referred to as calcitriol) improves the ability of macrophages to kill bacteria; however, higher levels of calcitriol lead to higher calcium levels, and thus hypercalcemia in some cases. Thus, hypercalcemia proves to be an important symptom of miliary tuberculosis.

Thirdly, chorodial tubercules, pale lesions on the optic nerve, typically indicate miliary tuberculosis in children. These lesions may occur in one eye or both; the number of lesions varies between patients. Chorodial tubercules may serve as important symptoms of miliary tuberculosis, since their presence can often confirm suspected diagnosis.

Lastly, between 10 and 30% of adults, and 20–40% of children with miliary tuberculosis have tuberculosis meningitis. This relationship results from myobacteria from miliary tuberculosis spreading to the brain and the subarachnoid space; as a result, leading to tuberculosis meningitis.

The risk factors for contracting miliary tuberculosis are being in direct contact with a person who has it, living in unsanitary conditions, and having an unhealthy diet. In the U.S., risk factors for contracting the disease include homelessness and HIV/AIDS.

Tuberculosis cutis orificialis (also known as "acute tuberculous ulcer" and "orificial tuberculosis") is a form of cutaneous tuberculosis that occurs at the mucocutaneous borders of the nose, mouth, anus, urinary meatus, and vagina, and on the mucous membrane of the mouth or tongue.

Onset of symptoms is often gradual, but in necrotizing staphylococcal or gram-negative bacillary pneumonias patients can be acutely ill. Cough, fever with shivering, and night sweats are often present. Cough can be productive of foul smelling purulent mucus (≈70%) or less frequently with blood in one third of cases). Affected individuals may also complain of chest pain, shortness of breath, lethargy and other features of chronic illness.

Those with a lung abscess are generally cachectic at presentation. Finger clubbing is present in one third of patients. Dental decay is common especially in alcoholics and children. On examination of the chest there will be features of consolidation such as localized dullness on percussion and bronchial breath sounds.

Lung abscess is a type of liquefactive necrosis of the lung tissue and formation of cavities (more than 2 cm) containing necrotic debris or fluid caused by microbial infection.

This pus-filled cavity is often caused by aspiration, which may occur during anesthesia, sedation, or unconsciousness from injury. Alcoholism is the most common condition predisposing to lung abscesses.

Lung abscess is considered primary (60%) when it results from existing lung parenchymal process and is termed secondary when it complicates another process e.g. vascular emboli or follows rupture of extrapulmonary abscess into lung.

A subcutaneous abscess is an abscess located in the subcutaneous tissue (also hypodermis). The abscess is formed due to a hypodermal infection by a bacterium, a fungus or a parasite. Typically, this kind of abscess needs drainage, usually for a minimum of 24 hours, by means of gauze packing or a Penrose drain.

Abscesses may occur in any kind of solid tissue but most frequently on skin surface (where they may be superficial pustules (boils) or deep skin abscesses), in the lungs, brain, teeth, kidneys, and tonsils. Major complications are spreading of the abscess material to adjacent or remote tissues, and extensive regional tissue death (gangrene).

The main symptoms and signs of a skin abscess are redness, heat, swelling, pain, and loss of function. There may also be high temperature (fever) and chills.

An internal abscess is more difficult to identify, but signs include pain in the affected area, a high temperature, and generally feeling unwell.

Internal abscesses rarely heal themselves, so prompt medical attention is indicated if such an abscess is suspected.

An abscess could potentially be fatal (although this is rare) if it compresses vital structures such as the trachea in the context of a deep neck abscess.

If superficial, abscesses may be fluctuant when palpated. This is a wave-like motion that is caused by movement of the pus inside the abscess.

As in the majority of paracoccidioidomycosis cases, pulmonary involvement results in shortness of breath, a productive cough and hemoptysis, as well as general symptoms of weight loss, fever and fatigue. Visually, lesions (as pictured) are often present, most commonly on the face.

Different types of discharges from ulcer are:

- Serous, usually seen in healing ulcer

- Purulent, seen in infected ulcer. Yellow creamy discharge is observed in staphylococcal infection; bloody opalescent discharge in streptococcal infection, while greenish discharge is seen in pseudomonas ulcer

- Bloody (sanguineous), usually seen in malignant ulcers and in healing ulcers with healthy granulation tissue

- Seropurulent

- Serosanguinous

- Serous with sulphur granules, seen in actinomycosis

- Yellowish, as seen in tuberculous ulcer

Tuberculous dactylitis is a skeletal manifestation of tuberculosis, one of the commonest bacterial osteitis. It affects children more often than adults. The first radiological description of the condition is credited to Feilchenfeld in 1896; however, the first histological description was given by Rankin in 1886. Multiple bones are involved in children and usually only a single bone is involved in adults suffering from tuberculous dactylitis. Tuberculous dactylitis affects the short tubular bones of the hands and feet in children. It often follows a mild course without fever and acute inflammatory signs as opposed to acute osteomyelitis. There may be a gap of a few months to 2 to 3 years from the time of initial infection to the point of diagnosis.

Spina ventosa is the term given for tuberculous dactylitis. Nearly 85% of the patients of spina ventosa are below 6 years of age.The bones of hands are more commonly involved than those of the feet. Proximal phalanx of the index and middle fingers are the commonest sites of involvement.Up to nearly 7% of children with pulmonary tuberculosis may develop this condition. Spread to the skeletal system is believed to occur via blood and lymphatics.

Fever, headache, and neurological problems, while classic, only occur in 20% of people with brain abscess.

The famous triad of fever, headache and focal neurologic findings are highly suggestive of brain abscess. These symptoms are caused by a combination of increased intracranial pressure due to a space-occupying lesion (headache, vomiting, confusion, coma), infection (fever, fatigue etc.) and focal neurologic brain tissue damage (hemiparesis, aphasia etc.).

The most frequent presenting symptoms are headache, drowsiness, confusion, seizures, hemiparesis or speech difficulties together with fever with a rapidly progressive course. Headache is characteristically worse at night and in the morning, as the intracranial pressure naturally increases when in the supine position. This elevation similarly stimulates the medullary vomiting center and area postrema, leading to morning vomiting.

Other symptoms and findings depend largely on the specific location of the abscess in the brain. An abscess in the cerebellum, for instance, may cause additional complaints as a result of brain stem compression and hydrocephalus. Neurological examination may reveal a stiff neck in occasional cases (erroneously suggesting meningitis).

Surgery of the anal fistula to drain an abscess treats the fistula and reduces likelihood of its recurrence and the need for repeated surgery. There is no evidence that fecal incontinence is a consequence of this surgery for abscess drainage.

Perianal abscesses can be seen in patients with for example inflammatory bowel disease (such as Crohn's disease) or diabetes. Often the abscess will start as an internal wound caused by ulceration, hard stool or penetrative objects with insufficient lubrication. This wound typically becomes infected as a result of the normal presence of feces in the rectal area, and then develops into an abscess. This often presents itself as a lump of tissue near the anus which grows larger and more painful with time. Like other abscesses, perianal abscesses may require prompt medical treatment, such as an incision and debridement or lancing.

Localized pain, often nocturnal, alleviated by aspirin. Often mimics the symptoms of Osteoid osteoma, which is typically less than 1 cm in diameter.

Paracoccidioidomycosis (PCM) (also known as "Brazilian blastomycosis," "South American blastomycosis,","Lutz-Splendore-de Almeida disease" and "paracoccidioidal granuloma") is a fungal infection caused by the fungus "Paracoccidioides brasiliensis". Sometimes called "South American blastomycosis", paracoccidioidomycosis is caused by a different fungus than that which causes blastomycosis.

Brain abscess (or cerebral abscess) is an abscess caused by inflammation and collection of infected material, coming from local (ear infection, dental abscess, infection of paranasal sinuses, infection of the mastoid air cells of the temporal bone, epidural abscess) or remote (lung, heart, kidney etc.) infectious sources, within the brain tissue. The infection may also be introduced through a skull fracture following a head trauma or surgical procedures. Brain abscess is usually associated with congenital heart disease in young children. It may occur at any age but is most frequent in the third decade of life.

Skin ulcers appear as open craters, often round, with layers of skin that have eroded. The skin around the ulcer may be red, swollen, and tender. Patients may feel pain on the skin around the ulcer, and fluid may ooze from the ulcer. In some cases, ulcers can bleed and, rarely, patients experience fever. Ulcers sometimes seem not to heal; healing, if it does occur, tends to be slow. Ulcers that heal within 12 weeks are usually classified as acute, and longer-lasting ones as chronic.

Ulcers develop in stages. In stage 1 the skin is red with soft underlying tissue. In the second stage the redness of the skin becomes more pronounced, swelling appears, and there may be some blisters and loss of outer skin layers. During the next stage, the skin may become necrotic down through the deep layers of skin, and the fat beneath the skin may become exposed and visible. In stage 4, deeper necrosis usually occurs, the fat underneath the skin is completely exposed, and the muscle may also become exposed. In the last two stages the sore may cause a deeper loss of fat and necrosis of the muscle; in severe cases it can extend down to bone level, destruction of the bone may begin, and there may be sepsis of joints.

Chronic ulcers may be painful. Most patients complain of constant pain at night and during the day. Chronic ulcer symptoms usually include increasing pain, friable granulation tissue, foul odour, and wound breakdown instead of healing. Symptoms tend to worsen once the wound has become infected.

Venous skin ulcers that may appear on the lower leg, above the calf or on the lower ankle usually cause achy and swollen legs. If these ulcers become infected they may develop an unpleasant odour, increased tenderness and redness. Before the ulcer establishes definitively, there may be a dark red or purple skin over the affected area as well as a thickening, drying, and itchy skin.

Although skin ulcers do not seem of great concern at a first glance, they are worrying conditions especially in people suffering from diabetes, as they are at risk of developing diabetic neuropathy.

Ulcers may also appear on the cheeks, soft palate, the tongue, and on the inside of the lower lip. These ulcers usually last from 7 to 14 days and can be painful.

Lepromatous leprosy is a form of leprosy characterized by pale macules in the skin.

It results from the failure of Th1 cell activation which is necessary to eradicate the mycobacteria (Th1 response is required to activate macrophages that engulf and contain the disease). In lepromatous leprosy, TH2 response is turned on, and because of reciprocal inhibition (IL-4; IL-10), the cell-mediated response (TH1) is depressed.

This debilitating form of leprosy begins to spread causing the eyebrows to disappear and spongy tumor like swellings appear on the face and body. The disease attacks the internal organs, bones, joints and marrow of the body resulting in physical degeneration. The result is deformity with loss of feeling in the fingers and toes which eventually fall off. Contrary to popular belief, both forms of leprosy are curable, with the lepromatous form classically treated with antibiotics Dapsone, Rifampin and Clofazimine for as long as 2–5 years, but if left untreated the person may die up to 20 or 30 years from its inception.

Early detection of the disease is of utmost importance, since severe physical and neurological damage are irreversible even if cured (e.g. blindness, loss of digits/limbs/sensation). Early infection is characterized by a well demarcated, usually pale, skin lesion which has lost its hair, and there may be many of these lesions if the infection is more severe (most commonly found on the cooler parts of the body such as the elbows, knees, fingers, or scrotum, as the bacteria thrive in cooler environments). This early presentation is the same for both tuberculous and lepromatous forms of leprosy as they are a spectrum of the same disease (lepromatous being the more contagious and severe form in patients with impaired Th1 response). Disease progression is extremely slow, and signs of infection may not appear for years.

Family members, and especially children, who have family members with the disease are most at risk. The disease is believed to be spread through respiratory droplets in close quarters like its relative Mycobacterium tuberculosis, and similarly requires extended exposure to an individual in most situations, so outsiders and healthcare workers are normally not infected (except with the most infective individuals such as those in the most progressed lepromatous forms, as those patients have the highest bacterial loads).