[4] Inflammatory pseudotumour is a generic term applied to various neoplastic and non-neoplastic tissue lesions which share a common microscopic appearance consisting of spindle cells and a prominent presence of the white blood cells that populate chronic or, less commonly, acute inflamed tissues.
[11] Tumors with these characteristics are regarded as a subtype of IMT termed epithelioid inflammatory myofibroblastic sarcoma (EIMS).
[3][11][12] The tumors in IMT and EIMS consistently contain pro-inflammatory white blood cells and in most cases tumor cells that express highly abnormal oncogenic (cancer-causing) fusion proteins such as those that contain the active portion of anaplastic lymphoma kinase (ALK).
[14] IMT was regarded as a tumor that occurs in children or young adults[13] and presented in the lung, mesentery, greater omentum or, less commonly, heart, liver, spleen, pancreas, colon, small intestine, spermatic cord, prostate, uterus, eye orbit, peripheral or central nervous system nerves, brain meninges, spinal cord, or other sites.
[13] Individual IMT cases are also reported to present in the urinary bladder, anal canal, and parameningeal spaces (i.e. sites adjacent to the meninges such as the nasopharynx, middle ear, paranasal sinuses, infratemporal fossa and pterygopalatine fossa).
[3][15] Individuals with IMT present with a wide range of symptoms (e.g. pain, swelling, a mass, organ dysfunction, etc.)
Up to 1/3 of these individuals have symptoms of systemic inflammation such as fever, chills, night sweats, and weight loss.
[2] Rare cases of IMT have developed in individuals with: a) organizing pneumonia; b) infection by Mycobacterium avium intracellulare or Corynebacterium equi (pneumonia-causing bacteria); Campylobacter jejuni (causes gastroenteritis); Lysinibacillus sphaericus (previously termed Bacillus sphaericus, a rare cause of lung infections[16] and sepsis);[17][18] Coxiella burneti (causes Q fever); Epstein–Barr virus (causes infectious mononucleosis and Epstein–Barr virus-associated lymphoproliferative malignant diseases); and E. coli-related occlusive phlebitis of intrahepatic veins; or c) previous abdominal surgery; trauma; ventriculoperitoneal shunt in the brain; radiation therapy; and corticosteroid usage.
Testing for the presence of the ALK fusion protein and other genetic abnormalities (see next section) can help diagnose IMT.
Tumors that are not resectable, occur in inaccessible sites, are multifocal, or have metastasized are treated with aggressive therapeutic regimens.
31 had no residual disease post-surgery; 4 of these patients had local relapses, 3 of whom were again treated surgically and 1 with surgery plus chemotherapy.
The various drug regimens showed little differences in effectiveness although patients treated with ALK inhibitors trended to have longer response times.
The study also evaluated 9 patients (aged 12–31 years, median age 16) treated with methotrexate + vinblastine, methotrexate + vinorelbine, or vinblastine + vinorelbine; 2 patients attained complete responses, 3 attained partial responses, 2 had steady disease, and 2 had progressive disease; this groups' progression-free time was not reached while its overall survival time was 83.4 months.
[34] Numerous Medical history studies have had similar results in treated IMT with ALK inhibitors.
[35][14][25][36] However, ALK inhibitors have serious side effects; in on study, crizotinib treatment was associated with pneumonia, fever of unknown cause, heart attack, sepsis, abdominal abscess, acute renal insufficiency, and the development of an abnormal EKG (i.e. QT prolongation).