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.

Lupus vulgaris often develops due to inadequately treated pre-existing tuberculosis. It may also develop at site of BCG vaccination. Rarely, it has been shown to be associated with tattoo mark and also with long term bindi use, the so-called "bindi tuberculosis".

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.

Granuloma annulare, microscopically, consists of dermal epithelioid histiocytes around a central zone of mucin - a so-called palisaded granuloma.

In longstanding scarred lesions, squamous cell carcinoma can develop.

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.

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

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

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.

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.

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.

Generalized granuloma annulare is a skin condition of unknown cause, tending to affect women in the fifth and sixth decades, presenting as a diffuse but symmetrical, papular or annular eruption of more than ten skin lesions, and often hundreds.

Majocchi's disease (also known as Majocchi's Granuloma, "Purpura annularis telangiectodes,", and "Purpura annularis telangiectodes of Majocchi") is well-recognized but uncommon skin condition characterized by purple/bluish-red 1- to 3-cm annular patches composed of dark red telangiectases with petechiae. The name Majocchi's comes from the Professor Domenico Majocchi who first discovered the disorder in 1883. Domenico Majocchi was a professor of dermatology at the University of Parma and later the University of Bologna. Majocchi's disease can be defined as an infection of the dermal and subcutaneous tissues due to a fungal mold infection on the cutaneous layer of the skin. The most common dermatophyte is called "Trichophyton rubrum." This disease can affect both immunocompetent and immunocompromised hosts. However, immunocompromised individuals have a higher risk.

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.

Granuloma annulare in HIV disease is a skin condition characterized typically by papular and generalized skin lesions.

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.

The disease mimics many other dermatoses and can be confused with conditions, such as sarcoidosis, discoid lupus erythematosus, mycosis fungoides, and fixed drug eruption.

The heritability of sarcoidosis varies according to ethnicity. About 20% of African Americans with sarcoidosis have a family member with the condition, whereas the same figure for European Americans is about 5%. Additionally, in African Americans, who seem to experience more severe and chronic disease, siblings and parents of sarcoidosis cases have about a 2.5-fold increased risk for developing the disease. Investigations of genetic susceptibility yielded many candidate genes, but only few were confirmed by further investigations and no reliable genetic markers are known. Currently, the most interesting candidate gene is "BTNL2"; several "HLA-DR" risk alleles are also being investigated. In persistent sarcoidosis, the HLA haplotype "HLA-B7-DR15" are either cooperating in disease or another gene between these two loci is associated. In nonpersistent disease, there is a strong genetic association with HLA DR3-DQ2. Cardiac sarcoid has been connected to TNFA variants.

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

The exact cause of sarcoidosis is not known. The current working hypothesis is, in genetically susceptible individuals, sarcoidosis is caused through alteration to the immune response after exposure to an environmental, occupational, or infectious agent. Some cases may be caused by treatment with TNF inhibitors like etanercept.

A foreign-body granuloma occurs when a foreign body (such as a wood splinter, piece of metal, glass etc.) penetrates the body's soft tissue followed by acute inflammation and formation of a granuloma. In some cases the foreign body can be found and removed even years after the precipitating event.

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.

Necrobiosis lipoidica is a necrotising skin condition that usually occurs in patients with diabetes mellitus but can also be associated with rheumatoid arthritis. In the former case it may be called necrobiosis lipoidica diabeticorum (NLD). NLD occurs in approximately 0.3% of the diabetic population, with the majority of sufferers being women (approximately 3:1 females to males affected).

The severity or control of diabetes in an individual does not affect who will or will not get NLD. Better maintenance of diabetes after being diagnosed with NLD will not change how quickly the NLD will resolve.

Many conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.

The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers by diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.

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 etiologies 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), etiology (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). 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.

Idiopathic facial aseptic granuloma is a cutaneous condition characterized by a chronic, painless, solitary nodule, reminiscent of an acne nodule, appearing on the cheeks of young children. It has a prolonged course, but spontaneously heals.