Patients mostly present with a hard lump in one breast without any sign of a systemic disease. Other possible symptoms include nipple retraction, pain, inflammation of the overlying skin, nipple discharge, fistula, enlarged lymph nodes, in rare case peau d'orange-like changes.

Presentation is mostly unilateral although a significant share of cases is bilateral, also in many cases contralateral or bilateral recurrences were documented.

Several cases occurring together with fever, polyarthralgia and erythema nodosum were documented.

Characteristic for idiopathic granulomatous mastitis are multinucleated giant cells and epithelioid histiocytes forming non-caseating granulomas around lobules. Often minor ductal and periductal inflammation is present. The lesion is in some cases very difficult to distinguish from breast cancer and other causes such as infections (tuberculosis, syphilis, corynebacterial infection, mycotic infection), autoimmune diseases (sarcoidosis, granulomatosis with polyangiitis), foreign body reaction and granulomatous reaction in a carcinoma must be excluded.

The condition is diagnosed very rarely. As the diagnosis is a lengthy differential diagnosis of exclusion there is considerable uncertainty about incidence. It has been suspected that some cases diagnosed as IGM in developing countries may have other explanations. On the other hand, IGM is usually diagnosed only after complications and referral to a secondary breast care center so light cases may resolve spontaneously or after symptomatic treatment and thus never be diagnosed as IGM. As a completely pathogen free breast will be exceedingly rare even in completely healthy population there is also uncertainty when to consider pathogens as causative or as mere coincidental finding.

Granulomatous mastitis can be divided into idiopathic granulomatous mastitis (also known as granular lobular mastitis) and granulomatous mastitis occurring as a rare secondary complication of a great variety of other conditions such as tuberculosis and other infections, sarcoidosis and granulomatosis with polyangiitis. Special forms of granulomatous mastitis occur as complication of diabetes. Some cases are due to silicone injection (Silicone-induced granulomatous inflammation) or other foreign body reactions.

Primary presentation of any of these conditions as mastitis is very rare and in many cases probably predisposed by other breast or systemic conditions.

Although granulomatous mastitis is easily confused with cancer it is a completely benign (non-cancerous) condition.

Treatment is radically different for idiopathic granulomatous mastitis and other granulomatous lesions of the breast, the precise diagnosis is therefore very important.

The term nonpuerperal mastitis describes inflammatory lesions of the breast (mastitis) that occur unrelated to pregnancy and breastfeeding.

It is sometimes equated with duct ectasia, but other forms can be described.

Comedo mastitis is a very rare form similar to granulomatous mastitis but with tissue necrosis. Because it is so rare it may be sometimes confused with comedo carcinoma of the breast although the conditions appear to be completely unrelated.

Palpation thyroiditis refers to the development of thyroid inflammation due to mechanical damage to thyroid follicles.This can occur by vigorous repeated palpation (as with thyroid examination) or surgical manipulation (as can occur with radical neck dissection). It is a type of subacute thyroiditis. Pathology shows multifocal granulomatous folliculitis. T cells predominate compared to B cells. There may be initial transient hyperthyroidism due to leakage of preformed thyroid hormone in blood.

Lactation mastitis usually affects only one breast and the symptoms can develop quickly. The signs and symptoms usually appear suddenly and they include:

- Breast tenderness or warmth to the touch

- General malaise or feeling ill

- Swelling of the breast

- Pain or a burning sensation continuously or while breast-feeding

- Skin redness, often in a wedge-shaped pattern

- Fever of 101 F (38.3 C) or greater

- The affected breast can then start to appear lumpy and red.

Some women may also experience flu-like symptoms such as:

- Aches

- Shivering and chills

- Feeling anxious or stressed

- Fatigue

Contact should be made with a health care provider with special breastfeeding competence as soon as the patient recognizes the combination of signs and symptoms. Most of the women first experience the flu-like symptoms and just after they may notice a sore red area on the breast. Also, women should seek medical care if they notice any abnormal discharge from the nipples, if breast pain is making it difficult to function each day, or they have prolonged, unexplained breast pain.

Signs and symptoms may include:

- Persistent or recurrent enlargement of the lips, causing them to protrude. If recurrent, the interval during which the lips are enlarged may be weeks or months. The enlargement can cause midline fissuring of the lip ("median cheilitis") or angular cheilitis (sores at the corner of the mouth). The swelling is non-pitting (c.f. pitting edema) and feels soft or rubbery on palpation. The mucous membrane of the lip may be erythemaous (red) and granular. One or both lips may be affected.

- Oral ulceration (mouth ulcers) which may be aphthous like, or be more chronic and deep with raised margins. Alternatively, lesions similar to pyostomatitis vegetans may occur in OFG, but this is uncommon.

- "Full width" gingivitis (compare with marginal gingivitis).

- Gingival enlargement (swelling of the gums).

- Fissured tongue (grooves in the tongue).

- Enlargement of the mucous membrane of the mouth, which may be associated with cobblestoning and mucosal tags (similar lesions often occur on the intestinal mucosa in Crohn's disease).

- Enlargement of the perioral and periorbital soft tissues (the tissues of the face around the mouth and the eyes). The facial skin may be dry, exfoliative (flaking) or erythematous.

- Cervical lymphadenopathy (enlarged lymph nodes in the neck).

- Facial palsy (weakness and altered sensation of the face).

The enlargement of the tissues of the mouth, lips and face seen in OFG is painless. Melkersson-Rosenthal syndrome is where OFG occurs with fissured tongue and paralysis of the facial nerve. The cause of the facial paralysis is thought to be caused by the formation of granulomas in the facial nerve, which supplies the muscles of facial expression.

Granulomatous prostatitis is an uncommon disease of the prostate, an exocrine gland of the male reproductive system. It is a form of prostatitis, i.e. inflammation of the prostate, resulting from infection (bacterial, viral, or fungal), the BCG therapy, malacoplakia or systemic granulomatous diseases which involve the prostate.

Prostatic secretions escape into the stroma and elicit an inflammatory response.

OFG could be classified as a type of cheilitis (lip inflammation), hence the alternative names for the condition using the word cheilitis, and a granulomatous condition.

The term nonpuerperal mastitis describes inflammatory lesions of the breast occurring unrelated to pregnancy and breastfeeding. This article includes description of mastitis as well as various kinds of mammary abscesses. Skin related conditions like dermatitis and foliculitis are a separate entity.

Names for non-puerperal mastitis are not used very consistently and include mastitis, subareolar abscess, duct ectasia, periductal inflammation, Zuska's disease and others.

Necrotizing granulomas can develop in patients with rheumatoid arthritis, typically manifesting as bumps in the soft tissues around the joints (so-called rheumatoid nodules) or in the lungs.

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.

Rhinoscleroma has been divided into 3 stages: catarrhal/atrophic, granulomatous, and sclerotic stages. The catarrhal stage begins with a nonspecific rhinitis, which progresses into purulent, fetid rhinorrhea, and crusting, which can last for weeks or even months. The granulomatous stage results in the development of a bluish red nasal mucosa and the development of intranasal rubbery nodules or polyps. Nose bleeds, nasal deformity, and destruction of the nasal cartilage are also noted (Hebra nose). The damage may result in anesthesia of the soft palate, enlargement of the uvula, dysphonia, and various degrees of airway obstruction. The fibrotic stage is characterized by sclerosis and fibrosis. Lymphadenitis is absent.

The changes in fibrocystic breast disease are characterised by the appearance of fibrous tissue and a lumpy, cobblestone texture in the breasts. These lumps are smooth with defined edges, and are usually free-moving in regard to adjacent structures. The bumps can sometimes be obscured by irregularities in the breast that are associated with the condition. The lumps are most often found in the upper, outer sections of the breast (nearest to the armpit), but can be found throughout the breast. Women with fibrocystic changes may experience a persistent or intermittent breast aching or breast tenderness related to periodic swelling. Breasts and nipples may be tender or itchy.

Symptoms follow a periodic trend tied closely to the menstrual cycle. Symptoms tend to peak in the days and, in severe cases, weeks before each period and decrease afterwards. At peak, breasts may feel full, heavy, swollen, and tender to the touch. No complications related to breastfeeding have been found.

Breast diseases can be classified either with disorders of the integument, or disorders of the reproductive system. A majority of breast diseases are noncancerous.

Subacute thyroiditis is a form of thyroiditis that can be a cause of both thyrotoxicosis and hypothyroidism. It is uncommon and can affect individuals of both sexes and people of all ages. The most common form, subacute granulomatous, or de Quervain's, thyroiditis manifests as a sudden and painful enlargement of the thyroid gland accompanied with fever, malaise and muscle aches. Indirect evidence has implicated viral infection in the aetiology of subacute thyroiditis. This evidence is limited to preceding upper respiratory tract infection, elevated viral antibody levels, and both seasonal and geographical clustering of cases. There may be a genetic predisposition.

Nishihara and coworkers studied the clinical features of subacute thyroiditis in 852 mostly 40- to 50-year-old women in Japan. They noted seasonal clusters (summer to early autumn) and most subjects presented with neck pain. Fever and symptoms of thyrotoxicosis was present in two thirds of subjects. Upper respiratory tract infections in the month preceding presentation were reported in only 1 in 5 subjects. Recurrent episodes following resolution of the initial episode were rare, occurring in just 1.6% of cases. Laboratory markers for thyroid inflammation and dysfunction typically peaked within one week of onset of illness.

Types include:

- Subacute granulomatous thyroiditis (De Quervain thyroiditis)

- Subacute lymphocytic thyroiditis

- Postpartum thyroiditis

- Palpation thyroiditis

In ICD-10 the condition is called "diffuse cystic mastopathy", or, if there is epithelial proliferation, "fibrosclerosis of breast". Other names for this condition include "chronic cystic mastitis", "fibrocystic mastopathy" and "mammary dysplasia". The condition has also been named after several people (see eponyms below). Since it is a very common disorder, some authors have argued that it should not be termed a "disease", whereas others feel that it meets the criteria for a disease. It is not a classic form of mastitis (breast inflammation).

Signs of duct ectasia can include nipple retraction, inversion, pain, and sometimes bloody discharge.

Sarcoidosis can be involved with the joints, bones and muscles. This causes a wide variety of musculoskeletal complaints that act through different mechanisms.

About 5–15% of cases affect the bones, joints, or muscles.

Arthritic syndromes can be categorized in two ways: as acute or chronic.

Sarcoidosis patients suffering acute arthritis often also have bilateral Hilar lymphadenopathy and Erythema nodosum. These three associated syndromes often occur together in Löfgren syndrome. The arthritis symptoms of Löfgren syndrome occur most frequently in the ankles, followed by the knees, wrists, elbows, and metacarpophalangeal joints. Usually true arthritis is not present, but instead, periarthritis appears as a swelling in the soft tissue around the joints that can be seen by ultrasonographic methods.

These joint symptoms tend to precede or occur at the same time as erythema nodosum develops. Even when erythema nodosum is absent, it is believed that the combination of hilar lymphadenopathy and ankle periarthritis can be considered as a variant of Löfgren syndrome.

Enthesitis also occurs in about one-third of patients with acute sarcoid arthritis, mainly affecting the Achilles tendon and heels. Soft tissue swelling of the ankles can be prominent, and biopsy of this soft tissue reveals no granulomas but does show panniculitis that is similar to erythema nodosum.

Chronic sarcoid arthritis usually occurs in the setting of more diffuse organ involvement. The ankles, knees, wrists, elbows, and hands may all be affected in the chronic form and often this presents itself in a polyarticular pattern. Dactylitis similar to that seen in Psoriatic arthritis, that is associated with pain, swelling, overlying skin erythema, and underlying bony changes may also occur. Development of Jaccoud arthropathy (a nonerosive deformity) is very rarely seen.

Bone involvement in sarcoidosis has been reported in 1–13% of cases. The most frequent sites of involvement are the hands and feet, whereas the spine is less commonly affected. Half of the patients with bony lesions experience pain and stiffness, whereas the other half remain asymptomatic.

Periostitis is rarely seen in Sarcoidosis and has been found to present itself at the femoral bone.

Abnormal blood tests are frequent, accounting for over 50% of cases, but are not diagnostic. Lymphopenia is the most common blood anomaly in sarcoidosis. Anemia occurs in about 20% of people with sarcoidosis. Leukopenia is less common and occurs in even fewer persons but is rarely severe. Thrombocytopenia and hemolytic anemia are fairly rare. In the absence of splenomegaly, leukopenia may reflect bone marrow involvement, but the most common mechanism is a redistribution of blood T cells to sites of disease. Other nonspecific findings include monocytosis, occurring in the majority of sarcoidosis cases, increased hepatic enzymes or alkaline phosphatase. People with sarcoidosis often have immunologic anomalies like allergies to test antigens such as "Candida" or purified protein derivative (PPD). Polyclonal hypergammaglobulinemia is also a fairly common immunologic anomaly seen in sarcoidosis.

Lymphadenopathy (swollen glands) is common in sarcoidosis and occurs in 15% of cases. Intrathoracic nodes are enlarged in 75 to 90% of all people; usually this involves the hilar nodes, but the paratracheal nodes are commonly involved. Peripheral lymphadenopathy is very common, particularly involving the cervical (the most common head and neck manifestation of the disease), axillary, epitrochlear, and inguinal nodes. Approximately 75% of cases show microscopic involvement of the spleen, although only in about 5–10% of cases does splenomegaly appear.

Rhinoscleroma, or simply scleroma, is a chronic granulomatous bacterial disease of the nose that can sometimes infect the upper respiratory tract. It most commonly affects the nasal cavity—the nose is involved in 95–100 per cent of cases—however, it can also affect the nasopharynx, larynx, trachea, and bronchi. Slightly more females than males are affected and patients are usually 10 to 30 years of age. Rhinoscleroma is considered a tropical disease and is mostly endemic to Africa and Central America, less common in the United States.

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.

Noninvasive methods to determine duct diameter in live patients are available only recently and it is not clear how the results should be compared with older results from biopsies.

Histologically, dilation of the large duct is prominent. Duct widening with associated periductal fibrosis is frequently included in the wastebasket definition of fibrocystic disease.

In plasma cell rich lesions diagnosed on core biopsies, steroid-responsive IgG4-related mastitis can be identified by IgG/IgG4 immunostaining.

Mastitis in dairy cattle is the persistent, inflammatory reaction of the udder tissue. Mastitis, a potentially fatal mammary gland infection, is the most common disease in dairy cattle in the United States. It is also the most costly to the dairy industry. Milk from cows suffering from mastitis has an increased somatic cell count.