A granuloma is one of a number of forms of localized nodular inflammation found in tissues. The fact that a granuloma is localized is important. So is its nodularity. Granulomas have a typical pattern when examined under a microscope. Granulomas can be caused by a variety of biologic, chemical and physical irritants of tissue. A calcified granuloma is a granuloma containing calcium deposits. Since it usually takes some time for calcium to be deposited in a granuloma, it is generally assumed that a calcified granuloma is an old granuloma. For example, a calcified granuloma in the lung may be due to tuberculosis contracted years earlier that is now dormant.
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Term applied to nodular inflammatory lesions, usually small or granular, firm, persistent, and containing compactly grouped modified phagocytes such as epithelioid cells, giant cells, and other macrophages. SEE ALSO: granulomatosis. [granulo- + G. -oma, tumor]
- actinic g. an annular eruption on sun-exposed skin which microscopically shows phagocytosis of dermal elastic fibers by giant cells and histiocytes. SYN: Miescher g..
- amebic g. SYN: ameboma.
- g. annulare a chronic or recurrent, usually self-limited papular eruption that tends to develop on the distal portions of the extremities and over prominences, although the condition may be generalized; waxy papules tend to form annular lesions characterized microscopically by foci of dermal necrosis with mucin deposits, bordered by histiocytes with palisaded nuclei.
- apical g. SYN: periapical g..
- beryllium g. a sarcoid-like granulomatous reaction to exposure to inhaled beryllium, or to skin cuts by fluorescent lamp glass.
- bilharzial g. SYN: schistosome g..
- Capillaria g. granulomatous lesions found in the liver and lung are a tissue response at the site of eggs or worms.
- cholesterol g. g. with prominent clefts of cholesterol surrounded by foreign-body giant cells found in chronic otitis media and sinusitis.
- coccidioidal g. SYN: secondary coccidioidomycosis.
- cutaneous leishmaniasis g. lymphocytic granulomas with necrotic centers found during the healing process.
- dental g. SYN: periapical g..
- Enterobius g. lesions containing dead worms and eggs of this nematode; have been found in vagina, cervix, fallopian tubes, omentum, peritoneum, liver, kidneys, and lungs.
- eosinophilic g. a form of Langerhans histiocytosis predominately involving the bones of young people; may be solitary or multiple; histologically composed of Langerhans cells and eosinophils.
- g. faciale persistent, well-demarcated, reddish-brown nodules of unknown cause that usually appear on the face in middle age and consist of a dense dermal infiltrate of eosinophils and neutrophils, separated from the epidermis and hair follicles, with fibrinoid vasculitis of unknown cause.
- fish-tank g. SYN: swimming pool g..
- foreign body g. a g. caused by the presence of foreign particulate material in tissue, characterized by a histiocytic reaction with foreign body giant cells.
- g. gangrenescens SYN: lethal midline g..
- giant cell g. a nonneoplastic lesion characterized by a proliferation of granulation tissue containing numerous multinucleated giant cells; it occurs on the gingiva and alveolar mucosa (occasionally on other soft tissues) where it presents as a soft red-blue hemorrhagic nodular swelling; it also occurs within the mandible or maxilla as a unilocular or multilocular radiolucency; microscopically similar lesions occur in the tubular bones of the hands and feet, are considered neoplastic, and may have a malignant course. Identical bony lesions may be seen in hyperparathyroidism and cherubism. SEE ALSO: giant cell tumor of bone. SYN: giant cell epulis, reparative giant cell g..
- g. gravidarum a pyogenic g. developing on the gingiva during pregnancy; thought to be related to hormonally altered response of the oral mucous membranes to local irritants such as bacterial plaque on adjacent teeth. SYN: pregnancy tumor.
- infectious g. any granulomatous lesion known to be caused by a living agent; e.g., bacteria, fungi, helminths.
- g. inguinale a specific g., classified as a venereal disease and caused by Calymmatobacterium granulomatis observed in macrophages as Donovan bodies; the ulcerating granulomatous lesions occur in the inguinal regions and the genitalia; peripheral extension of the lesions produces extensive destruction. SYN: g. venereum.
- laryngeal g. a polypoid projection of granulomatous tissue into the lumen of the larynx, commonly following a traumatic tracheal intubation.
- lethal midline g. 1. destruction of the nasal septum, hard palate, lateral nasal walls, paranasal sinuses, skin of the face, orbit and nasopharynx by an inflammatory infiltrate with atypical lymphocytic and histiocytic cells; a form of lymphoma in most cases. 2. obsolete term for polymorphic reticulosis. SYN: g. gangrenescens, malignant g., midline malignant reticulosis g..
- lipoid g. g. characterized by aggregates or accumulations of fairly large mononuclear phagocytes that contain lipid.
- lipophagic g. a lesion formed as a result of the inflammatory reaction provoked by foci of necrosis in subcutaneous fat, as in certain types of traumatic injury; the central focus of necrotic material is surrounded by an irregular zone of numerous macrophages, many of which become laden with tiny globules of lipid.
- lymphatic filariasis g. granulomatous lesion often found surrounding dead microfilariae.
- Majocchi granulomas inflammatory ringworm of the glabrous skin. SYN: tinea profunda.
- malignant g. SYN: lethal midline g..
- Miescher g. SYN: actinic g..
- g. multiforme a chronic granulomatous annular eruption of the skin on the upper body in older adults in central Africa; of unknown cause.
- ocular larva migrans g. eosinophilic granulomata found surrounding dead worms (generally, Toxocara spp.) in the eye; may mimic retinoblastoma.
- oily g. reaction to inclusion of a bulky, insoluble liquid (often an oily substance) which occurs several months, but sometimes years, after injection of the material.
- paracoccidioidal g. SYN: paracoccidioidomycosis.
- Paragonimus g. lesions caused by adult worms and eggs of the lung fluke trapped in the pulmonary parenchyma.
- periapical g. a proliferation of granulation tissue surrounding the apex of a nonvital tooth and arising in response to pulpal necrosis. SYN: apical g., dental g., root end g..
- pulse g. SYN: giant cell hyaline angiopathy.
- pyogenic g., g. pyogenicum an acquired small rounded mass of highly vascular granulation tissue, frequently with an ulcerated surface, projecting from the skin, especially of the face, or oral mucosa; histologically, the mass is a lobular capillary hemangioma. SYN: lobular capillary hemangioma.
- reparative g. complication of stapedectomy in which a g. forms in the oval window around the prosthesis; it results in a sensory hearing loss.
- reparative giant cell g. SYN: giant cell g..
- root end g. SYN: periapical g..
- sarcoidal g. a non-necrotizing epithelioid cell g. similar to those seen in sarcoidosis.
- schistosome g. a granulomatous lesion formed around schistosome eggs embedded in tissues in cases of schistosomiasis (bilharziasis); typically these granulomata are found in intestinal tissues (Schistosoma japonicum or S. mansoni infection), bladder tissue (S. haematobium), and hepatic tissue (all human schistosomes). SYN: bilharzial g..
- sea urchin g. granulomatous nodules, either foreign-body type or composed of epithelioid cells, from the retention of the spine of the sea urchin, occurring several months after the wounding of the skin.
- silica g. eruption of granulomatous lesions due to traumatic inoculation of the skin with sand, or materials that contain silica; this condition may follow dermabrasion using sandpaper technique.
- silicotic g. granulomatous nodule resulting from deposition of silica particles, usually occurring in lung.
- swimming pool g. a chronic, verrucous lesion most commonly seen on the knees; due to infection by Mycobacterium marinum. SYN: fish-tank g..
- trichinosis g. lesions caused by cell death after penetration of migrating newborn nematode larvae.
- g. tropicum SYN: yaws.
- umbilical g. moist granulation tissue at the center of the umbilicus in neonates.
- g. venereum SYN: g. inguinale.
- zirconium g. g. from zirconium salts, usually occurring in the axillae, from antiperspirants containing this material, or from the application of hydrous zirconium oxide to poison ivy lesions.

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gran·u·lo·ma .gran-yə-'lō-mə n, pl -mas also -ma·ta -mət-ə a mass or nodule of chronically inflamed tissue with granulations that is usu. associated with an infective process

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n. (pl. granulomata or granulomas)
a localized collection of cells, usually produced in response to an infectious process, that is characterized by the presence of epithelioid histiocyte; giant cells, monocytes, or other lymphocytes may also be present. The types of cells comprising a granuloma (of which there may be many or few) and their arrangement can assist in diagnosing the cause of the response; this is important in the diagnosis of tuberculosis, sarcoidosis, Crohn's disease, and the presence of certain foreign bodies (e.g. starch, talc). Other conditions giving rise to granulomata include syphilis, leprosy, and coccidioidomycosis, and a granuloma may also occur around the apex of a tooth root as a result of inflammation or infection of its pulp.
granulomatous adj.

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gran·u·lo·ma (gran″u-loґmə) pl. granulomas, granuloґmata [granul- + -oma] an imprecise term applied to either a small, nodular, delimited aggregation of mononuclear inflammatory cells, or a similar collection of epithelioid cells; it is usually surrounded by a rim of lymphocytes and often includes multinucleated giant cells. Some granulomas contain eosinophils and plasma cells, and many are accompanied by fibrosis. Granuloma formation represents a chronic inflammatory response that can be initiated by infectious or noninfectious agents. See also granulomatosis.

Medical dictionary. 2011.

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