Chronic granulomatous inflammation is a disease process that mostly affects the soft tissues and is an inflammation where a compact collection of cells of the mononuclear phagocyte system, chiefly activated macrophages and cells derived from them are predominant 1.
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Pathology
There are two major categories of chronic granulomatous inflammation 2:
epitheloid or high sensitivity / high cell turnover granulomas
Etiology
The disease is mostly considered to result from a response to pathogens and persistent irritants of either exogenous or endogenous origin 3. Often times, post surgical involvement also is a contributing factor.
Microscopic appearance
Numerous mixed chronic inflammatory cells composed of lymphocytes, plasma cells, histiocytes and poorly formed granuloma on a fibroid background and multinucleated giant cells. sometimes, there is evidence of central necrosis.
Radiographic appearance
Plain radiograph
Soft tissue edema with radio-lucent areas however. No gross skeletal bone involvement.
Ultrasound
Diffuse soft tissue thickening (mostly peritendinous and/or purely subcutaneous in location) with mixed heterogenous echopattern and lobulations and sometimes interspersed with clear anechoic fluid areas. Color Doppler may be avascular or hypovascular. there may be presence of enlarged, reactive regional or distant lymph nodes.
MRI
If fluid is present, non-contrast T1W images will demonstrate central hypo-intensities while T2W images will demonstrate increased signal intensity regions in the background of thickened and lobulated mixed intensity soft tissue signal areas.
Differential diagnosis
post surgical fibrosis