Soft tissue
Fibroblastic / myofibroblastic
Inflammatory myofibroblastic tumor
Author: Komal Arora, M.D.
Topic Completed: 1 May 2012
Minor changes: 13 January 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Inflammatory myofibroblastic tumor of soft tissue
Table of Contents
Definition / general | Clinical features | Prognostic factors | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Molecular / cytogenetics images | Differential diagnosisCite this page: Arora K. Inflammatory myofibroblastic tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissueinflammyofibro.html. Accessed January 18th, 2021.
Definition / general
- Tumor of myofibroblasts with plasma cells, lymphocytes and eosinophils
- Also called inflammatory fibrosarcoma, inflammatory pseudotumor, plasma cell granuloma
- See also discussions in these chapters: Bladder, Breast, Colon tumor, Eye (orbit), Liver, Lung, Lymph node, Small bowel, Thyroid gland
- Retroperitoneum (omentum) and mesentery in children and young adults (mean age 10 years)
- Also lung, GI, GU, other sites
Clinical features
- 1/3 have associated fever, growth failure, malaise, weight loss, anemia, thrombocytosis, polyclonal hyperglobulinemia and elevated sedimentation rate
- Symptoms disappear after excision of mass (J Korean Med Sci 2002;17:699)
Prognostic factors
- Poor
- Abdominal or pelvic sites, ALK negative (Am J Surg Pathol 2007;31:509)
Case reports
- 4 year old boy with fever, colicky epigastric pain and lower midline abdominal lesion (Case of the Week #400)
- 6 year old boy with abdominal wall tumor (Surg Today 2007;37:352)
- 7 year old girl whose abdominopelvic tumor has t(1;2)(q21;p23) (Arch Pathol Lab Med 2006;130:1042)
- 18 year old man with omental tumor and bone marrow involvement (Arch Pathol Lab Med 2003 Jul;127:865)
- 46 year old woman with retroperitoneal tumor (World J Surg Oncol 2005;3:66)
- 63 year old man with mesenteric tumor (World J Gastroenterol 2007;13:3645)
Treatment
- Excision (J Pediatr Surg 2005;40:1581)
- 25 - 35% recur, rare metastases (or may be evidence of multifocality)
Gross description
- Circumscribed, not encapsulated
- White tan mass with whorled fleshy or myxoid cut surface
- May have focal hemorrhage, necrosis or calcification, mean 6 cm
Gross images
Images hosted on other servers:
Tumor at the mesentery of proximal jejunum
Mesentery of both jejunum and ileum
Well circumscribed, grayish white
Microscopic (histologic) description
- Myofibroblastic and fibroblastic spindle cells with inflammatory infiltrate of lymphocytes, plasma cells, eosinophils, histiocytes
- Background of abundant blood vessels
- Mixture of three patterns:
- Resembling nodular fasciitis with elongated myofibroblasts containing abundant eosinophilic cytoplasm and vesicular nuclei, loose myxoid stroma with neutrophils, lymphocytes and eosinophils, but few plasma cells;
- Cellular with spindled myofibroblasts and fibroblasts in more compact stroma, arranged as islands surrounded by fibromyxoid stroma with prominent plasma cells and mitotic figures;
- Densely hyalinized stroma with few spindle cells, few plasma cells or lymphocytes
- May have ganglion-cell like myofibroblasts
- All 3 patterns have no nuclear pleomorphism, no atypical mitotic figures
- Malignant behavior: associated with highly atypical polygonal cells with oval nuclei, prominent nucleoli, Reed-Sternberg like cells, atypical mitotic figures
Microscopic (histologic) images
Case #400 - epithelioid inflammatory myofibroblastic sarcoma (EIMS):
ALK
Contributed by Mark R. Wick, M.D.
Various images
ALK
AFIP images
Typical appearance of spindled myofibroblastic cells and inflammatory infiltrate
Inflammation obscures the underlying myofibroblastic proliferation
Spindle cells are evident at high power
Tumor with more fibrous stroma
Images hosted on other servers:
Myofibroblasts and inflammatory cells
Retroperitoneal tumor
Positive stains
- Vimentin (diffuse, strong), usually alpha smooth muscle actin, muscle specific actin and calponin (Hum Pathol 2008;39:846)
- ALK1 / p80 in 40%, but not specific (Mod Pathol 2002;15:931)
- Keratin and desmin in 1/3
Negative stains
Electron microscopy description
- Myofibroblastic cells and activated fibroblasts
Molecular / cytogenetics description
- Clonal abnormalities of 2p23 (Cancer Res 1999;59:2776) including t(2;5)(p23;q35) involving ALK and NPM
- Also t(2;17)(p23;q23) involving ALK and CLTC (Am J Pathol 2001;159:411) and t(2;19)(p23;p13.1) involving ALK and TPM4 (Am J Pathol 2000;157:377)
- Associated with ALK deregulation and younger patients
- See Atlas of Genetics
Molecular / cytogenetics images
Images hosted on other servers:
t(2;5) karyotype
ALK staining, FISH and karyotype
Differential diagnosis
- Calcifying fibrous pseudotumor: calcification, no myofibroblastic proliferation, actin negative (Mod Pathol 2001;14:784)
- IgG4 related sclerosing lesion: IgG4+ plasma cells and the ratio of IgG4+ / IgG+ plasma cells is lower in IMT
- Low grade myofibroblastic sarcoma: more uniform appearance with higher cellularity, more prominent hyperchromasia, more infiltrative, ALK (Hum Pathol 2008;39:846)
- Nodular fasciitis: smaller size, older patients, less inflammation
- The presence of obstructive phlebitis
- Absence of ALK (Mod Pathol 2011;24:606, Am J Surg Pathol 2009;33:1330)
