Inflammatory myofibroblastic tumour

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Inflammatory myofibroblastic tumour 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
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.
  • Classically located in mesentery of ileocolic region or small bowel.[1]

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.[5]

Images

IHC

Features - dependent on site:

  • SMA +ve.[6]
  • Vimentin +ve.

Variable staining with:

  • CD34, AE1/AE3, calretinin.[7][6]

Negative:[6]

  • S100, CD117, CD68.

Others:

  • ALK-1 +ve. ???

Molecular

  • ALK rearrangements.[4]

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 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.
  5. URL: http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970283-2. Accessed on: 10 May 2011.
  6. 6.0 6.1 6.2 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. Cite error: Invalid <ref> tag; name "pmid20350216" defined multiple times with different content
  7. 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.