Inflammatory myofibroblastic tumour

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Inflammatory myofibroblastic tumour, abbreviated IMT, is an uncommon soft tissue lesion.

Inflammatory myofibroblastic tumour
Diagnosis in short

Inflammatory myofibroblastic tumour. H&E stain.

LM inflammation (plasma cells - predominant, lymphocytes, eosinophils), spindle cells without atypia +/-fascicular architecture, +/-mitoses (none atypical), +/-necrosis, +/-hemorrhage, +/-calcification
LM DDx calcifying fibrous pseudotumour, inflammatory fibroid tumour, nodular fasciitis, gastrointestinal stromal tumour, epithelioid inflammatory myofibroblastic sarcoma
Site soft tissue - see fibroblastic/myofibroblastic tumours

Prevalence uncommon
Prognosis benign
Clin. DDx other soft tissue lesions

It is also known as inflammatory pseudotumour, and inflammatory fibrosarcoma[1] and plasma cell granuloma.[2][3]

General

  • Mostly benign.
  • Children & young adults.

Gross

Microscopic

Features:[1]

  • Inflammation:
  • Spindle cells without atypia.
  • +/-Fascicular architecture.
  • Mitoses -- though none atypical.
  • +/-Necrosis.
  • +/-Hemorrhage.
  • Calcifications.

DDx:

Notes:

  • Some consider this a wastebasket diagnosis... for benign appearing spindle cell lesions.[7]

Images

IHC

Features - dependent on site:

  • SMA +ve.[8]
  • Vimentin +ve.
  • ALK-1 +ve.[4]
  • CD117 -ve.
    • Case report of CD117 +ve.[6]

Variable staining with:

  • CD34, AE1/AE3, calretinin.[9][8]

Negative:[8]

  • S100, CD117, CD68.

Molecular

  • ALK rearrangements.[5]
  • ROS1 rearrangements.[10]

See also

References

  1. 1.0 1.1 1.2 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 610. ISBN 978-0781765275.
  2. URL: http://www.uptodate.com/contents/inflammatory-myofibroblastic-tumor-plasma-cell-granuloma-of-the-lung. Accessed on: 27 November 2011.
  3. Manohar, B.; Bhuvaneshwari, S. (Jan 2011). "Plasma cell granuloma of gingiva.". J Indian Soc Periodontol 15 (1): 64-6. doi:10.4103/0972-124X.82275. PMID 21772725.
  4. 4.0 4.1 Tsuzuki, T.; Magi-Galluzzi, C.; Epstein, JI. (Dec 2004). "ALK-1 expression in inflammatory myofibroblastic tumor of the urinary bladder.". Am J Surg Pathol 28 (12): 1609-14. PMID 15577680.
  5. 5.0 5.1 5.2 Saab, ST.; Hornick, JL.; Fletcher, CD.; Olson, SJ.; Coffin, CM. (Apr 2011). "IgG4 plasma cells in inflammatory myofibroblastic tumor: inflammatory marker or pathogenic link?". Mod Pathol 24 (4): 606-12. doi:10.1038/modpathol.2010.226. PMID 21297584.
  6. 6.0 6.1 Kataoka, TR.; Yamashita, N.; Furuhata, A.; Hirata, M.; Ishida, T.; Nakamura, I.; Hirota, S.; Haga, H. et al. (2014). "An inflammatory myofibroblastic tumor exhibiting immunoreactivity to KIT: a case report focusing on a diagnostic pitfall.". World J Surg Oncol 12: 186. doi:10.1186/1477-7819-12-186. PMID 24938355.
  7. URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970283-2. Accessed on: 10 May 2011.
  8. 8.0 8.1 8.2 Shi, H.; Li, Y.; Wei, L.; Sun, L. (Apr 2010). "Primary colorectal inflammatory myofibroblastic tumour: a clinicopathological and immunohistochemical study of seven cases.". Pathology 42 (3): 235-41. doi:10.3109/00313021003631312. PMID 20350216.
  9. Miyamoto, H.; Montgomery, EA.; Epstein, JI. (Apr 2010). "Paratesticular fibrous pseudotumor: a morphologic and immunohistochemical study of 13 cases.". Am J Surg Pathol 34 (4): 569-74. doi:10.1097/PAS.0b013e3181d438cb. PMID 20216379.
  10. Mai, S.; Xiong, G.; Diao, D.; Wang, W.; Zhou, Y.; Cai, R. (Feb 2019). "Case report: Crizotinib is effective in a patient with ROS1-rearranged pulmonary inflammatory myofibroblastic tumor.". Lung Cancer 128: 101-104. doi:10.1016/j.lungcan.2018.12.016. PMID 30642440.