A granuloma is an aggregation of
macrophage
Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer cel ...
s that forms in response to chronic
inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...
. This occurs when the
immune system
The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
attempts to isolate foreign substances that it is otherwise unable to eliminate.
Such substances include
infectious organisms including
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
and
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
, as well as other materials such as
foreign objects,
keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...
, and
suture fragments.
Definition
In
pathology
Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in ...
, a granuloma is an organized collection of macrophages.
[
In medical practice, doctors occasionally use the term ''granuloma'' in its more literal meaning: "a small nodule". Since a small nodule can represent any tissue from a harmless ]nevus
Nevus (plural nevi) is a nonspecific medical term for a visible, circumscribed, chronic lesion of the skin or mucosa. The term originates from ''nævus'', which is Latin for "birthmark"; however, a nevus can be either congenital (present at bir ...
to a malignant tumor
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal ble ...
, this use of the term is not very specific. Examples of this use of the term ''granuloma'' are the lesions
A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals.
Types
There is no designated classifi ...
known as vocal cord
In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speech ...
granuloma (known as contact granuloma
Contact granuloma is a condition that develops due to persistent tissue irritation in the posterior larynx. Granulation tissue, Benign granulomas, not to be confused with other types of granulomas, occur on the vocal process of the vocal folds, whe ...
), pyogenic granuloma
A pyogenic granuloma or lobular capillary hemangioma is a vascular tumor that occurs on both mucosa and skin, and appears as an overgrowth of tissue due to irritation, physical trauma, or hormonal factors. It is often found to involve the gums, ...
, and intubation
Intubation (sometimes entubation) is a medical procedure involving the insertion of a tube into the body. Patients are generally anesthetized beforehand. Examples include tracheal intubation, and the balloon tamponade with a Sengstaken-Blakemo ...
granuloma, all of which are examples of granulation tissue
Granulation tissue is new connective tissue and microscopic blood vessels that form on the surfaces of a wound during the healing process. Granulation tissue typically grows from the base of a wound and is able to fill wounds of almost any size ...
, not granulomas. "Pulmonary hyalinizing granuloma" is a lesion characterized by keloid
Keloid, also known as keloid disorder and keloidal scar,
is the formation of a type of scar which, depending on its maturity, is composed mainly of either type III (early) or type I (late) collagen. It is a result of an overgrowth of granulation t ...
-like fibrosis in the lung and is not granulomatous. Similarly, radiologists
Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiatio ...
often use the term ''granuloma'' when they see a calcified nodule on X-ray or CT scan of the chest. They make this assumption since granulomas usually contain calcium, although the cells that form a granuloma are too tiny to be seen by a radiologist. The most accurate use of the term ''granuloma'' requires a pathologist
Pathology is the study of the causal, causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when us ...
to examine surgically removed and specially colored (stained) tissue under a microscope.
Histiocyte
A histiocyte is a vertebrate cell that is part of the mononuclear phagocyte system (also known as the reticuloendothelial system or lymphoreticular system). The mononuclear phagocytic system is part of the organism's immune system. The histiocyt ...
s (specifically macrophages) are the cells that define a granuloma. They often fuse to form multinucleated giant cells (Langhans giant cell
Langhans giant cells are large cells found in granulomatous conditions.
They are formed by the fusion of epithelioid cells ( macrophages), and contain nuclei arranged in a horseshoe-shaped pattern in the cell periphery.
Although traditionally ...
). The macrophages in granulomas are often referred to as " epithelioid". This term refers to the vague resemblance of these macrophages to epithelial cells
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...
. Epithelioid macrophages differ from ordinary macrophages in that they have elongated nuclei that often resemble the sole of a slipper or shoe. They also have larger nuclei than ordinary macrophages, and their cytoplasm is typically pinker when stained with eosin
Eosin is the name of several fluorescent acidic compounds which bind to and form salts with basic, or eosinophilic, compounds like proteins containing amino acid residues such as arginine and lysine, and stains them dark red or pink as a resul ...
. These changes are thought to be a consequence of "activation" of the macrophage by the offending antigen
In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...
.
The other key term in the above definition is the word "organized" which refers to a tight, ball-like formation. The macrophages in these formations are typically so tightly clustered that the borders of individual cells are difficult to appreciate. Loosely dispersed macrophages are not considered to be granulomas.
All granulomas, regardless of cause, may contain additional cells and matrix
Matrix most commonly refers to:
* ''The Matrix'' (franchise), an American media franchise
** ''The Matrix'', a 1999 science-fiction action film
** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...
. These include lymphocytes
A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic adap ...
, neutrophils
Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying in ...
, eosinophils
Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...
, multinucleated giant cells
A giant cell (also known as multinucleated giant cell, or multinucleate giant cell) is a mass formed by the union of several distinct cells (usually histiocytes), often forming a granuloma. Although there is typically a focus on the pathological ...
, fibroblasts
A fibroblast is a type of biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells o ...
, and collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...
(fibrosis
Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perma ...
). The additional cells are sometimes a clue to the cause of the granuloma. For example, granulomas with numerous eosinophils may be a clue to coccidioidomycosis
Coccidioidomycosis (, ), commonly known as cocci, Valley fever, as well as California fever, desert rheumatism, or San Joaquin Valley fever, is a mammalian fungal disease caused by ''Coccidioides immitis'' or ''Coccidioides posadasii''. Coccidio ...
or allergic bronchopulmonary fungal disease, and granulomas with numerous neutrophils suggest blastomycosis
Blastomycosis or blasto is a fungal infection caused by inhaling spores of a ''Blastomyces'' fungus. Only about half of people with the disease have symptoms, which can include fever, cough, night sweats, muscle pains, weight loss, chest pain, a ...
, granulomatosis with polyangiitis
Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis (WG), is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis ...
, aspiration pneumonia
Aspiration pneumonia is a type of lung infection that is due to a relatively large amount of material from the stomach or mouth entering the lungs. Signs and symptoms often include fever and cough of relatively rapid onset. Complications may inclu ...
, or cat-scratch disease
Cat-scratch disease (CSD) or felinosis is an infectious disease that most often results from a scratch or bite of a cat. Symptoms typically include a non-painful bump or blister at the site of injury and painful and swollen lymph nodes. People m ...
.
In terms of the underlying cause, the difference between granulomas and other types of inflammation is that granulomas form in response to antigens that are resistant to "first-responder" inflammatory cells such as neutrophils
Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying in ...
and eosinophils
Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...
. The antigen causing the formation of a granuloma is most often an infectious pathogen or a substance foreign to the body, but sometimes the offending antigen is unknown (as in sarcoidosis
Sarcoidosis (also known as ''Besnier-Boeck-Schaumann disease'') is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly af ...
).
Granulomas are seen in a wide variety of diseases, both infectious and noninfectious. Infections characterized by granulomas include tuberculosis
Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in ...
, leprosy
Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacteria ''Mycobacterium leprae'' or ''Mycobacterium lepromatosis''. Infection can lead to damage of the nerves, respiratory tract, skin, and eyes. This nerve damag ...
, histoplasmosis
Histoplasmosis is a fungal infection caused by ''Histoplasma capsulatum''. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; called disseminated histoplasmosis, it can ...
, cryptococcosis
Cryptococcosis is a potentially fatal fungal infection of mainly the lungs, presenting as a pneumonia, and brain, where it appears as a meningitis. Cough, difficulty breathing, chest pain and fever are seen when the lungs are infected. When the ...
, coccidioidomycosis
Coccidioidomycosis (, ), commonly known as cocci, Valley fever, as well as California fever, desert rheumatism, or San Joaquin Valley fever, is a mammalian fungal disease caused by ''Coccidioides immitis'' or ''Coccidioides posadasii''. Coccidio ...
, blastomycosis
Blastomycosis or blasto is a fungal infection caused by inhaling spores of a ''Blastomyces'' fungus. Only about half of people with the disease have symptoms, which can include fever, cough, night sweats, muscle pains, weight loss, chest pain, a ...
, and cat-scratch disease. Examples of noninfectious granulomatous diseases are sarcoidosis, Crohn's disease
Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), fever, abdominal distension ...
, berylliosis
Berylliosis, or chronic beryllium disease (CBD), is a chronic allergic-type lung response and chronic lung disease caused by exposure to beryllium and its compounds, a form of beryllium poisoning. It is distinct from acute beryllium poisoning, whi ...
, granulomatosis with polyangiitis
Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis (WG), is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis ...
, eosinophilic granulomatosis with polyangiitis
Eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as allergic granulomatosis, is an extremely rare autoimmune condition that causes inflammation of small and medium-sized blood vessels (vasculitis) in persons with a history of ...
, pulmonary rheumatoid nodules, and aspiration of food and other particulate material into the lung.
An important feature of granulomas is whether or not they contain necrosis
Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
, which refers to dead cells that, under the microscope, appear as a mass of formless debris with no nuclei present. A related term, ''caseation
Caseous necrosis or caseous degeneration () is a unique form of cell death in which the tissue maintains a cheese-like appearance.Robbins and Cotran: Pathologic Basis of Disease, 8th Ed. 2010. Pg. 16 It is also a distinctive form of coagulative nec ...
'' (literally: ''turning to cheese'') refers to a form of necrosis that, to the unaided eye, appears cheese-like ("caseous"), and is typically a feature of the granulomas of tuberculosis. The identification of necrosis in granulomas is important because granulomas with necrosis tend to have infectious causes. Several exceptions to this general rule exist, but it nevertheless remains useful in day-to-day diagnostic pathology.
Image:Granuloma 20x.jpg, Granuloma without necrosis in a lymph node of a person with sarcoidosis
Image:Necrogran10x.jpg, Granuloma with central necrosis in a lung of a person with tuberculosis: Note the Langhans-type giant cells (with many nuclei arranged in a horseshoe-like pattern at the edge of the cell) around the periphery of the granuloma. Langhans-type giant cells are seen in many types of granulomas and are not specific for tuberculosis.
Diseases with granulomas
Tuberculosis
''Mycobacterium tuberculosis
''Mycobacterium tuberculosis'' (M. tb) is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' has an unusual, waxy coating on its c ...
'' can cause the granulomas of tuberculosis
Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in ...
which tend to contain necrosis ("caseating tubercules"), but non-necrotizing granulomas may also be present. Multinucleated giant cells with nuclei arranged like a horseshoe (Langhans giant cell) and foreign body giant cells are often present, but are not specific for tuberculosis. A definitive diagnosis of tuberculosis requires identification of the causative organism by microbiologic cultures.
Leprosy
In leprosy
Leprosy, also known as Hansen's disease (HD), is a long-term infection by the bacteria ''Mycobacterium leprae'' or ''Mycobacterium lepromatosis''. Infection can lead to damage of the nerves, respiratory tract, skin, and eyes. This nerve damag ...
, granulomas are found in the skin and tend to involve nerves. The appearance of the granulomas differs according to the precise type of leprosy.
Aquarium granuloma
The other Mycobacterium species, ''Mycobacterium marinum
''Mycobacterium marinum'' is a slow growing mycobacterium (SGM) belonging to the genus ''Mycobacterium'' and the phylum Actinobacteria. The strain marinum was first identified by Aronson in 1926 and it is observed as a pathogenic mycobacterium. F ...
'' can cause a rare infection known as "aquarium granuloma
Aquarium granuloma (also known as fish tank granuloma and swimming pool granuloma) is a rare skin condition caused by a non-tubercular mycobacterium known as ''Mycobacterium marinum''. Skin infections with ''M. marinum'' in humans are relatively u ...
."
Schistosomiasis
Some schistosome
''Schistosoma'' is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed ''schistosomiasis'', which is considered by the World Health Organi ...
ova that are laid in intestinal and urinary venules backwash into the liver via the portal vein, causing granuloma formation in the liver.
Histoplasmosis
Granulomas are seen in most forms of histoplasmosis
Histoplasmosis is a fungal infection caused by ''Histoplasma capsulatum''. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; called disseminated histoplasmosis, it can ...
(acute histoplasmosis, histoplasmoma, chronic histoplasmosis). ''Histoplasma'' organisms can sometimes be demonstrated within the granulomas by biopsy or microbiological cultures.
Cryptococcosis
When ''Cryptococcus
''Cryptococcus'' is a genus of fungi in the family Cryptococcaceae that includes both yeasts and filamentous species. The filamentous, sexual forms or teleomorphs were formerly classified in the genus ''Filobasidiella'', while ''Cryptococcus'' ...
'' infection occurs in persons whose immune systems are intact, granulomatous inflammation is typically encountered. The granulomas can be necrotizing or non-necrotizing. Using a microscope and appropriate stains, organisms can be seen within the granulomas.
Cat-scratch disease
Cat-scratch disease is an infection caused by the bacterial organism ''Bartonella henselae
''Bartonella henselae'', formerly ''Rochalimæa henselae'', is a bacterium that is the causative agent of cat-scratch disease ( bartonellosis).
''Bartonella henselae'' is a member of the genus ''Bartonella'', one of the most common types of bacte ...
'', typically acquired by a scratch from a kitten infected with the organism. The granulomas in this disease are found in the lymph nodes draining the site of the scratch. They are characteristically "suppurative", i.e., pus
Pus is an exudate, typically white-yellow, yellow, or yellow-brown, formed at the site of inflammation during bacterial or fungal infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection ...
-forming, containing large numbers of neutrophils. Organisms are usually difficult to find within the granulomas using methods routinely used in pathology laboratories.
Rheumatic fever
Rheumatic fever
Rheumatic fever (RF) is an inflammatory disease that can involve the heart, joints, skin, and brain. The disease typically develops two to four weeks after a streptococcal throat infection. Signs and symptoms include fever, multiple painful jo ...
is a systemic disease affecting the periarteriolar connective tissue and can occur after an untreated group A, beta-hemolytic streptococcal
''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occur ...
pharyngeal infection. It is believed to be caused by antibody cross-reactivity.
Sarcoidosis
Sarcoidosis
Sarcoidosis (also known as ''Besnier-Boeck-Schaumann disease'') is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly af ...
is a disease of unknown cause characterized by non-necrotizing ("non-caseating") granulomas in multiple organs and body sites, most commonly the lungs and lymph nodes within the chest cavity. Other common sites of involvement include the liver, spleen, skin, and eyes. The granulomas of sarcoidosis are similar to those of tuberculosis and other infectious granulomatous diseases. In most cases of sarcoidosis, though, the granulomas do not contain necrosis and are surrounded by concentric scar tissue (fibrosis
Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perma ...
). Sarcoid granulomas often contain star-shaped structures called ''asteroid bodies
An asteroid body is a microscopic finding seen within the giant cells of granulomas in diseases such as sarcoidosis and foreign-body giant cell reactions.
There is controversy about their composition. Traditionally, they were thought to be cyto ...
'' or lamellar
A ''lamella'' (plural ''lamellae'') is a small plate or flake, from the Latin, and may also be used to refer to collections of fine sheets of material held adjacent to one another, in a gill-shaped structure, often with fluid in between though s ...
structures termed ''Schaumann bodies
In pathology, Schaumann bodies are calcium and protein inclusions inside of Langhans giant cells as part of a granuloma.
Many conditions can cause Schaumann bodies, including:
*Sarcoidosis,
*Hypersensitivity pneumonitis, and
*Berylliosis.
*uncom ...
'', but these structures are not specific for sarcoidosis. Sarcoid granulomas can resolve spontaneously without complications or heal with residual scarring. In the lungs, this scarring can cause a condition known as pulmonary fibrosis
Pulmonary fibrosis is a condition in which the lungs become scarred over time. Symptoms include shortness of breath, a dry cough, feeling tired, weight loss, and nail clubbing. Complications may include pulmonary hypertension, respiratory failu ...
that impairs breathing. In the heart, it can lead to rhythm disturbances, heart failure, and even death.
Crohn's disease
Crohn's disease
Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), fever, abdominal distension ...
is an inflammatory condition of uncertain cause characterized by severe inflammation in the wall of the intestines and other parts of the abdomen. Within the inflammation in the gut wall, granulomas are often found and are a clue to the diagnosis.
''Listeria monocytogenes''
''Listeria monocytogenes
''Listeria monocytogenes'' is the species of pathogenic bacteria that causes the infection listeriosis. It is a facultative anaerobic bacterium, capable of surviving in the presence or absence of oxygen. It can grow and reproduce inside the host' ...
'' infection in infants can cause potentially fatal disseminated granulomas, called granulomatosis infantiseptica, following ''in utero'' infection.
''Leishmania'' spp.
Leishmaniases are a group of human diseases caused by ''Leishmania
''Leishmania'' is a parasitic protozoan, a single-celled organism of the genus '' Leishmania'' that are responsible for the disease leishmaniasis. They are spread by sandflies of the genus ''Phlebotomus'' in the Old World, and of the genus '' ...
'' genus and transmitted by a sandfly
Sandfly (or sand fly) is a colloquial name for any species or genus of flying, biting, blood-sucking dipteran (fly) encountered in sandy areas. In the United States, ''sandfly'' may refer to certain horse flies that are also known as "greenhea ...
bite can lead to granulomatous inflammation in skin ( cutaneous form of the disease) and liver (visceral
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a ...
form), with research suggesting effective granuloma formation to be desirable in the resolution of the disease.
Pneumocystis pneumonia
Pneumocystis
The Pneumocystidomycetes are a class of ascomycete fungi. It includes the single order Pneumocystidales, which contains the single monotypic family Pneumocystidaceae, which in turn contains the genus
Genus ( plural genera ) is a taxonomic r ...
infection in the lungs is usually not associated with granulomas, but rare cases are well documented to cause granulomatous inflammation. The diagnosis is established by finding Pneumocystis yeasts within the granulomas on lung biopsies.
Aspiration pneumonia
Aspiration pneumonia
Aspiration pneumonia is a type of lung infection that is due to a relatively large amount of material from the stomach or mouth entering the lungs. Signs and symptoms often include fever and cough of relatively rapid onset. Complications may inclu ...
is typically caused by aspiration of bacteria from the oral cavity into the lungs, and does not result in the formation of granulomas. Granulomas may form, though, when food particles or other particulate substances such as pill fragments are aspirated into the lungs. Patients typically aspirate food because they have esophageal, gastric, or neurologic problems. Intake of drugs that depress neurologic function may also lead to aspiration. The resultant granulomas are typically found around the airways (bronchioles), and are often accompanied by foreign body-type, multinucleated giant cells, acute inflammation, or organizing pneumonia. The finding of food particles in lung biopsies is diagnostic.
Rheumatoid arthritis
Necrotizing granulomas can develop in patients with rheumatoid arthritis
Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are involv ...
, typically manifesting as bumps in the soft tissues around the joints (so-called rheumatoid nodules) or in the lungs.
Granuloma annulare
Granuloma annulare
Granuloma annulare (GA) is a common, sometimes chronic skin condition which presents as reddish bumps on the skin arranged in a circle or ring. It can initially occur at any age, though two-thirds of patients are under 30 years old, and it is se ...
is a skin disease of unknown cause in which granulomas are found in the dermis of the skin, but it is not a true granuloma. Typically, a central zone of necrobiotic generation of collagen is seen, with surrounding inflammation and mucin deposition on pathology.
Foreign-body granuloma
A foreign-body granuloma
A foreign body reaction (FBR) is a typical tissue response to a foreign body within biological tissue. It usually includes the formation of a foreign body granuloma. Tissue-encapsulation of an implant is an example, as is inflammation around a sp ...
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.
Childhood granulomatous periorificial dermatitis
Childhood granulomatous periorificial dermatitis
Childhood granulomatous periorificial dermatitis (CGPD), is a rare benign granulomatous skin disease of unknown cause. The disorder was first described in 1970 by Gianotti in a case series of five children. CGPD is more common in boys than girls ...
is a rare granulomatous skin disorder of unknown cause. It is temporary and tends to affect children, usually of African descent.
Granulomas associated with vasculitis
Certain inflammatory diseases are characterised by a combination of granulomatous inflammation and vasculitis
Vasculitis is a group of disorders that destroy blood vessels by inflammation. Both arteries and veins are affected. Lymphangitis (inflammation of lymphatic vessels) is sometimes considered a type of vasculitis. Vasculitis is primarily caused b ...
(inflammation of the blood vessels). Both the granulomas as well as the vasculitis tend to occur in association with necrosis
Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
. Classic examples of such diseases include granulomatosis with polyangiitis
Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis (WG), is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis ...
and eosinophilic granulomatosis with polyangiitis
Eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as allergic granulomatosis, is an extremely rare autoimmune condition that causes inflammation of small and medium-sized blood vessels (vasculitis) in persons with a history of ...
.
Etymology
The term is and ''-oma'', a suffix used to indicate tumors or masses. The plural is granulomas or granulomata. The adjective granulomatous means "characterized by granulomas".
See also
*Lick granuloma
A lick granuloma, also known as acral lick dermatitis, is a skin disorder found most commonly in dogs, but also in cats. In dogs, it results typically from the dog's urge to lick the lower portion of one of their legs.
The lesion can initially be ...
, a skin disorder in dogs that results from dog's urge to lick the lower portion of its leg
*Sperm granuloma
A sperm granuloma is a lump of leaked sperm that appears along the vasa deferentia or epididymides in vasectomized individuals. While majority of sperm granulomas are present along the vas deferens, the rest of them form at the epididymis. Sper ...
*Contact granuloma
Contact granuloma is a condition that develops due to persistent tissue irritation in the posterior larynx. Granulation tissue, Benign granulomas, not to be confused with other types of granulomas, occur on the vocal process of the vocal folds, whe ...
, i.e. "throat granuloma"
References
External links
{{Cutaneous ketatosis, ulcer, atrophy, necrobiosis, and vasculitis
Anatomical pathology
Inflammations