Cutaneous actinomycosis is a chronic disease that affects the deep subcutaneous tissue of the skin. Caused by an anaerobic, Gram-positive, filamentous type of bacteria in the genus "Actinomyces", invasion of the soft tissue leads to the formation of abnormal channels leading to the skin surface (external sinus tracts) that discharge pale yellow sulfur granules.

This disease is uncommon, and has non-specific clinical features, making it difficult to diagnose.

Cervicofacial, pulmonary/thoracic and gastrointestinal forms exist, yet cervicofacial disease accounts for two-thirds of reported infections.

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.

The disease is characterised by the formation of painful abscesses in the mouth, lungs, breast, or gastrointestinal tract. Actinomycosis abscesses grow larger as the disease progresses, often over months. In severe cases, they may penetrate the surrounding bone and muscle to the skin, where they break open and leak large amounts of pus, which often contains characteristic granules (sulfur granules) filled with progeny bacteria. These granules are named due to their appearance, but are not actually composed of sulfur.

It is a common condition in weaned calves, young bulls, and heifers. The disease has a chronic course, and the general condition can remain quite good.

There is a swelling of the maxilla and mandible. Fistulisation occurs after some days, leaving a thick, yellowish, non-odorous pus, with mineralised, 2 to 5 mm grains therein.

Later on, a granuloma will form in the place of fistulisation.

The bony lesions are followed by periostitis, with permanent deformation of the facial bones.

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.

"Actinomycosis" is a rare infectious bacterial disease caused by "Actinomyces" species. About 70% of infections are due to either "Actinomyces israelii" or "A. gerencseriae". Infection can also be caused by other "Actinomyces" species, as well as "Propionibacterium propionicus", which presents similar symptoms. The condition is likely to be polymicrobial aerobic anaerobic infection.

Pulmonary infection

- Produces a virulent form of pneumonia (progressive)

- Night sweats, fever, cough, chest pain

- Pulmonary nocardiosis is subacute in onset and refractory to standard antibiotherapy

- Symptoms are more severe in immunocompromised individuals

- Radiologic studies show multiple pulmonary infiltrates with tendency to central necrosis

Neurological infection

- Headache, lethargy, confusion, seizures, sudden onset of neurological deficit

- CT scan shows cerebral abscess

- Nocardial meningitis is difficult to diagnose

Cardiac conditions

- Nocardia has been highly linked to endocarditis as a main manifestation

- In recorded cases, it has caused damage to heart valves whether natural or prosthetic

Lymphocutaneous disease

- Nocardial cellulitis is akin to erysipelas but is less acute

- Nodular lymphangeitis mimics sporotrichosis with multiple nodules alongside a lymphatic pathway

- Chronic subcutaneous infection is a rare complication and osteitis may ensue

- May be misidentified and treated for as a staph infection, specifically superficial skin infections

- Cultures must sit more than 48 hours to guarantee an accurate test

Ocular disease

- Very rarely nocardiae cause keratitis

- Generally there is a history of ocular trauma

Disseminated nocardiosis

- Dissemination occurs through the spreading enzymes possessed by the bacteria

- Disseminated infection can occur in very immunocompromised patients

- It generally involves both lungs and brain

- Fever, moderate or very high can be seen

- Multiple cavitating pulmonary infiltrates develop

- Cerebral abscesses arise later

- Cutaneous lesions are very rarely seen

- If untreated, the prognosis is poor for this form of disease

Cutaneous amoebiasis refers to a form of amoebiasis that presents primarily in the skin.

It can be caused by "Acanthamoeba" or "Entamoeba histolytica". When associated with "Acanthamoeba", it is also known as "cutaneous acanthamoebiasis".

It is also known as "amoebiasis cutis".

"Balamuthia mandrillaris" can cause cutaneous amoebiasis, but can prove fatal if the amoeba enters the bloodstream

Actinomycosis in animals is caused by "Actinomyces bovis" (whereas human infections are usually due to "A. israelii").

Actinomycosis is a quite common condition in cattle, where it is referred to as "lumpy jaw" or "senfed" (moroccan arabic), but it can also occur in horses, swine, dogs and rarely in sheep. In all these species, actinomycosis results in cold abscess, with granulomatous formations on the fistulised place.

Actinobacillosis is a zoonotic disease caused by Actinobacillus.

It is more commonly associated with animals than with humans.

One of the most common forms seen by veterinarians is mouth actinobacillosis of cattle, due to "Actinobacillus lignieresii". The most prominent symptom is the swelling of the tongue that comes out of the mouth and is very hard at palpation ("wooden tongue").

"Actinobacillus suis" is an important disease of pigs of all ages and can lead to severe morbidity and sudden death.

Nocardiosis is an infectious disease affecting either the lungs ("pulmonary nocardiosis") or the whole body ("systemic nocardiosis"). It is due to infection by bacterium of the genus Nocardia, most commonly "Nocardia asteroides" or "Nocardia brasiliensis".

It is most common in men, especially those with a weakened immune system. In patients with brain infection, mortality exceeds 80%; in other forms, mortality is 50%, even with appropriate therapy.

It is one of several conditions that have been called the great imitator. Cutaneous nocardiosis commonly occurs in immunocompetent hosts.

Mouth actinobacillosis of cattle must be differentiated from actinomycosis that affects bone tissues of the maxilla.

The disease usually affects the lower legs or scrotum. The swelling is accompanied by rough nodules or wart-like plaques on the skin. If the disease is not treated, it eventually results in pain and immobility.

Elephantiasis nostras is a cutaneous condition, a final hypertrophic fibrosis following longstanding chronic lymphangitis.

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

Ulcerative sarcoidosis is a cutaneous condition affecting roughly 5% of people with sarcoidosis.

Annular sarcoidosis is a cutaneous condition characterized by papular skin lesions arranged in annular

patterns, usually with a red-brown hue.

A cutaneous condition is any medical condition that affects the integumentary system—the organ system that encloses the body and includes skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment.

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying causes and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), cause (skin conditions resulting from physical factors), and so on.

Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow). The diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data. The introduction of cutaneous ultrasound has allowed the detection of cutaneous tumors, inflammatory processes, nail disorders and hair diseases.

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.

The disease is characterized by cutaneous and renal changes with the latter being ultimately fatal.

Common symptoms include, but are not limited to:

- Cutaneous lesions involving erythema, erosion, ulceration occurring mainly on extremities such as distal limbs, muzzle and ventrum

- Pyrexia (fever)

- Lethargy or malaise

- Anorexia

- Vomiting or retching

Sarcoidosis involves the skin in about 25% of patients. The most common lesions are erythema nodosum, plaques, maculopapular eruptions, subcutaneous nodules, and lupus pernio. Treatment is not required, since the lesions usually resolve spontaneously in two to four weeks. Although it may be disfiguring, cutaneous sarcoidosis rarely causes major problems.

An ameboma, also known as an amebic granuloma, is a rare complication of "Entamoeba histolytica" infection, where in response to the infecting amoeba there is formation of annular colonic granulation, which results in a large local lesion of the bowel.

The ameboma may manifest as a right lower quadrant abdominal mass, which may be mistaken for carcinoma, tuberculosis, Crohn's disease, actinomycosis, or lymphoma.

"Distribution" refers to how lesions are localized. They may be confined to a single area (a patch) or may exist in several places. Some distributions correlate with the means by which a given area becomes affected. For example, contact dermatitis correlates with locations where allergen has elicited an allergic immune response. Varicella zoster virus is known to recur (after its initial presentation as chicken pox) as herpes zoster ("shingles"). Chicken pox appears nearly everywhere on the body, but herpes zoster tends to follow one or two dermatomes; for example, the eruptions may appear along the bra line, on either or both sides of the patient.

- Generalized

- Symmetric: one side mirrors the other

- Flexural: on the front of the fingers

- Extensor: on the back of the fingers

- Intertriginous: in an area where two skin areas may touch or rub together

- Morbilliform: resembling measles

- Palmoplantar: on the palm of the hand or bottom of the foot

- Periorificial: around an orifice such as the mouth

- Periungual/subungual: around or under a fingernail or toenail

- Blaschkoid: following the path of Blaschko's lines in the skin

- Photodistributed: in places where sunlight reaches

- Zosteriform or dermatomal: associated with a particular nerve

Although a clear understanding of the various skin lesions in IgG4-related disease is a work in progress, skin lesions have been classified into subtypes based on documented cases:

- Angiolymphoid hyperplasia with eosinophilia (or lesions that mimic it) and cutaneous pseudolymphoma

- Cutaneous plasmacytosis

- Eyelid swelling (as part of Mikulicz's disease)

- Psoriasis-like eruptions

- Unspecified maculopapular or erythematous eruptions

- Hypergammaglobulinemic purpura and urticarial vasculitis

- Impaired blood supply to fingers or toes, leading to Raynaud's phenomenon or gangrene

Note:

In addition, Wells syndrome has also been reported in a case of IgG4-related disease.

Perforating calcific elastosis (also known as "Localized acquired cutaneous pseudoxanthoma elasticum," "Perforating periumbilical calcific elastosis," and "Periumbilical perforating pseudoxanthoma elasticum") is an acquired, localized cutaneous disorder, most frequently found in obese, multiparous, middle-aged women, characterized by lax, well-circumscribed, reticulated or cobble-stoned plaques occurring in the periumbilical region with keratotic surface papules.