The exact cause of Majocchi's granuloma is not well established however a dysfunctinoal immune system may be a causative factor. The first form of MG, the superficial perifollicular form occurs predominately on the legs of otherwise healthy young women who repeatedly shave their legs and develop hair follicle occlusions that directly or indirectly disrupt the follicle and allow for passive introduction of the organism into the dermis. Hence, the physical barrier of the skin is important because it prevents the penetration of microorganisms. Physical factors that play a major role in inhibiting dermal invasion include the interaction among keratin production, the rate of epidermal turnover, the degree of hydration and lipid composition of the stratum corneum, CO levels, and the presence or absence of hair. Keratin and/or necrotic material can also be introduced into the dermis with an infectious organism to further enhance the problem. In immunocompromised individuals, the use of topical corticosteroids may lead to a dermatophyte infection due to local immunosuppression.

Aquarium granuloma (also known as "fish tank granuloma" and "swimming pool granuloma") is a skin condition caused by "Mycobacterium marinum", characterized by a skin lesion that presents roughly three weeks after exposure.

Historically, there have been many types of dermatophytes that were known to cause Majocchi's granuloma. Trichophyton violaceum used to be one of the most common species of dermatophytes to cause this disease. Today, however, Trichophyton rubrum proves to be the main culprit is most cases. These fungi are keratinophilic and colonize or infect the superficial keratinized tissues (the skin, nails, and hair) of humans and animals. The organisms are usually restricted to the non-living cornified layer of the epidermis and do not invade beyond the epidermis. The fungi are usually unable to penetrate into viable tissues in a immunocompetent host and therefore many times the infection incidence is higher in immune compromised individuals. There are two forms of MG: (i) the small, perifollicular papular form, which is a localized dermal infection that usually occurs in healthy individuals and (ii) the form featuring deep subcutaneous plaques or nodular lesions that occur in immunosuppressed hosts. Tinea corporis is the name of the subset of this disease that only remains restricted to the stratum corneum. Otherwise, the atypical deeper involvement is known as Majocchi's granuloma. Because keratinophilic dermatophytes digest keratin, the introduction of keratin into the dermis may also act as a medium for continued growth of the organism.

Fungal folliculitis (also known as Majocchi granuloma) is a skin condition characterized by a deep, pustular type of tinea circinata resembling a carbuncle or kerion.

Annular elastolytic giant-cell granuloma (also known as "Giant cell elastophagocytosis," "Meischer's granuloma," "Miescher's granuloma of the face") is a cutaneous condition characterized histologically by a dermal infiltrate of macrophages.

The formation of gummata is rare in developed countries, but common in areas that lack adequate medical treatment.

Syphilitic gummas are found in most but not all cases of tertiary syphilis, and can occur either singly or in groups. Gummatous lesions are usually associated with long-term syphilitic infection; however, such lesions can also be a symptom of benign late syphilis.

Localized granuloma annulare has a tendency towards spontaneous resolution. Localized lesions have been treated with potent topical corticosteroids.

Eosinophilic granuloma is a form of Langerhans cell histiocytosis. It is a condition of both human and veterinary pathology. Colloquially, the reaction pattern is sometimes referred to as a rodent ulcer.

Feline eosinophilic granuloma complex is synonymous with "feline eosinophilic skin diseases". This is considered to be a cutaneous reaction pattern that can be the manifestation of a number of underlying infections, allergies or ectoparasite infestations. It can also be idiopathic, that is have no known underlying trigger. The eosinophilic reaction is common in feline inflammatory disease and the eosinophilic granuloma can be a hereditary reaction pattern in some lines of domestic cats.

Subcutaneous granuloma annulare (also known as "Deep granuloma annulare," and "Pseudorheumatoid nodule") is a skin condition of unknown cause, most commonly affecting children, with girls affected twice as commonly as boys, characterized by skin lesions most often on the lower legs.

Actinic granuloma (also known as "O'Brien granuloma") is a cutaneous condition characterized histologically by a dermal infiltrate of macrophages.

Actinic granuloma is an asymptomatic granulomatous reaction that affects sun-exposed skin, most commonly on the face, neck, and scalp.

It is characterized by annular or polycyclic lesions that slowly expand centrifugally and have an erythematous elevated edge and a hypopigmented, atrophic center.

Advise to reduce exposure to the sun and to use sunscreen.

Treatment with topical halometasone cream, pimecrolimus cream.

Aside from the mosquito allergy cat, cats with EGC usually have allergy, ectoparasite infestation or possibly ringworm or other skin infection. Other implicated causes include traumatic damage, autoimmune disease or FeLV infection.

The condition is usually seen in otherwise healthy people. Occasionally, it may be associated with diabetes or thyroid disease. It has also been associated with auto-immune diseases such as systemic lupus erythematosus, rheumatoid arthritis, Lyme disease and Addison's disease. At this time no conclusive connection has been made between patients.

The microorganism spreads from one host to another through contact with the open sores.

Angiolymphoid hyperplasia with eosinophilia (also known as: "Epithelioid hemangioma," "Histiocytoid hemangioma," "Inflammatory angiomatous nodule," "Intravenous atypical vascular proliferation," "Papular angioplasia," "Inflammatory arteriovenous hemangioma," and "Pseudopyogenic granuloma") usually presents with pink to red-brown, dome-shaped, dermal papules or nodules of the head or neck, especially about the ears and on the scalp.

It, or a similar lesion, has been suggested as a feature of IgG4-related skin disease, which is the name used for skin manifestations of IgG4-related disease.

The disease is effectively treated with antibiotics, therefore, developed countries have a very low incidence of donovanosis; about 100 cases reported each year in the United States. However, sexual contacts with individuals in endemic regions dramatically increases the risk of contracting the disease. Avoidance of these sexual contacts, and sexually transmitted disease testing before beginning a sexual relationship, are effective preventative measures for donovanosis.

Lobomycosis also known as (Jorge) Lobo's disease or lacaziosis, is a blastomycosis, a fungal infection of the skin caused by "Lacazia loboi" (formerly named "Loboa loboi"), and discovered by Brazilian dermatologist Jorge Lobo. Other names which were given to the disease are: keloidal blastomycosis, Amazonian blastomycosis, blastomycoid granuloma, miraip and piraip. These last two names were given by natives of the Amazon and mean "that which burns".

This disease is usually found in humans and bottle-nosed dolphins, with the possible risk of transmission from one species to the next.

"Listeria monocytogenes" infection in infants can cause potentially fatal disseminated granulomas, called granulomatosis infantiseptica, following "in utero" infection.

Granuloma annulare is a fairly rare, chronic skin condition which presents as reddish bumps on the skin arranged in a circle or ring. It can initially occur at any age and is four times more common in females.

Rheumatic fever is a systemic disease affecting the peri-arteriolar connective tissue and can occur after an untreated Group A Beta-hemolytic streptococcal pharyngeal infection. It is believed to be caused by antibody cross-reactivity.

Lesions in dolphins occur on the dorsal fin, head, , and peduncle. In January 2006, a potential epidemic of lobomycosis was reported in dolphins of the Indian River Lagoon in Florida.

Perforating granuloma annulare is a skin condition of unknown cause, usually appearing on the dorsal hands, presenting as papules with a central keratotic core.

Patch-type granuloma annulare (also known as "Macular granuloma annulare") is a skin condition of unknown cause, more commonly affecting women between 30 and 70 years of age, characterized by flat or slightly palpable erythematous or red-brown skin lesions.

A common cause of lick granuloma appears to be psychological, related to stress, anxiety, separation anxiety, boredom, or compulsiveness. Lick granulomas are especially seen in large active dogs left alone for long periods of time. It is often considered to be a form of canine obsessive-compulsive disorder.

But other less common causes include bacterial or fungal infections, trauma causing nerve damage, allergies, or joint disease. Hot spots may also lead to the formation of lick granulomas.

Many large breed dogs appear to be predisposed, as well as golden retrievers and other bird dogs. Most of the dogs with the condition are over five years of age. Seventy percent of the time it occurs on one of the dog's left legs. Arthritic and mobility problems in older dogs give them more time to lick and over-groom themselves.

Frequent formations of lick granulomas in the same area due to the constant licking will cause hardening, callous formation, hair loss (the hair may stop growing back), and hyperpigmentation to that area. The condition becomes a vicious cycle – erosion of the skin from licking leads to pain and itching, which leads to more licking. Lick granulomas sometimes become infected with bacteria, causing abscessed areas or fistulous tracts (furuncles).

Prognosis is usually good, however recurrence may happen with rate up to 16%. Presence of myxoid structures in the pyogenic granuloma may be the main cause of recurrence.

Although pyogenic granulomas are not infectious or malignant, treatment may be considered because of bleeding or ulceration. Frequently, pyogenic granulomas are treated with electrodesiccation (cauterization) and curettage (excision), though laser treatment using pulsed dye laser or CO laser is often effective.

Several reports have demonstrated the efficacy of topical application of the beta-adrenergic antagonist timolol in the treatment of pediatric pyogenic granuloma.

There is usually no treatment if the pyogenic granuloma occurs during pregnancy since the lesion may heal spontaneously. Recurrent bleeding in either oral or nasal lesions may necessitate excision and cauterization sooner, however. If aesthetics are a concern, then treatment may be pursued as well. Usually, only minor surgery may be needed, along with a dental cleaning for oral lesions to remove any calculus or other source of irritation. For nasal lesions, nose-picking should be discouraged.

The appearance of pyogenic granuloma is usually a color ranging from red/pink to purple, and can be smooth or lobulated. Younger lesions are more likely to be red because of the high number of blood vessels. Older lesions begin to change into a pink color. Size commonly ranges from a few millimeters to centimeters, though smaller or larger lesions may occur. A pyogenic granuloma can be painful, especially if located in an area of the body where it is constantly disturbed. Pyogenic granulomas can grow rapidly and will often bleed profusely with little or no trauma. They may exude an oil like substance, causing the surface to be damp. This is especially true if the granuloma is located on the scalp.

Pyogenic granulomas may be seen at any age, and are more common in females than males. In pregnant women, lesions may occur in the first trimester with an increasing incidence up until the seventh month, and are often seen on the gums. Epulis granulomatosum is a variant of pyogenic granuloma that forms only on gingiva, and is often seen forming in a recent extraction socket. Pyogenic granulomas appear on the gingiva in 75% of cases, more often in the maxillary than mandibular jaw. Anterior areas are more often affected than posterior areas. It can also be found on the lips, tongue, and inner cheek. Poor oral hygiene or trauma are usually precipitating factors.

One study has suggested a correlation between pyogenic granulomas and Bartonella seropositivity. However, this association has been questioned by others. The microscopic appearance of a pyogenic granuloma consists of highly vascular granulation tissue. Inflammation is present. The lesion may have a fibrous character if it is older, and the surface may have ulcerations. Pyogenic granulomas rarely occur in the conjunctiva, cornea or connective tissue of the eye following minor local trauma. Grossly these mass lesions resemble those occurring at more common sites. The relationship of these lesion to lobular capillary hemangiomas of skin and oropharyngeal mucosa commonly referred to as pyogenic granuloma is uncertain.