inflammatory pseudotumor

{{Short description|Cell proliferation involving spindle cells}}

An inflammatory pseudotumor is a cell proliferation and inflammation involving spindle cells, which may occur in many parts of the body, and is of unknown case.{{cite book |last1=Gnepp |first1=Douglas R. |last2=Bishop |first2=Justin A. |title=Gnepp's Diagnostic Surgical Pathology of the Head and Neck |date=5 May 2020 |publisher=Elsevier Health Sciences |isbn=978-0-323-54780-2 |page=984 |url=https://books.google.com/books?id=Hl_hDwAAQBAJ&pg=PA984 |language=en}}

According to the WHO classification, three lesional patterns can be observed:

• Inflammatory myofibroblastic tumour, that can be associated with an ALK gene rearrangement
• Plasmocytic pattern ("plasma cell granuloma"), that can be linked to IgG4-related disease
• Fibrous and hyalinizing pattern: Pulmonary hyalinizing granuloma