Inflammatory myofibroblastic tumour

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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

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

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]

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.