The term inflammatory pseudotumour (IPT) has been used to describe varying entities sharing histological features of a fibroblast or myofibroblast proliferation with an associated prominent chronic inflammatory cell infiltrate (see review ). The non-neoplastic members of this entity are generally reactive processes following infection or inflammation.
A subset of these cases would now be classified under the umbrella of IgG4-related disease. There is also a clear neoplastic group, now preferentially known as inflammatory myofibroblastic tumour (IMT), which shows distinct clinical and molecular characteristics including, in ~50% of cases, ALK tyrosine kinase translocations.
The term inflammatory pseudotumour is unhelpful in that even the non-neoplastic entities frequently present as tumours (in the Latin meaning of a swelling or mass). The neoplastic form, as discussed, is clearly 'tumour' and use of the term 'pseudotumour' can be misleading. Older literature that pre-dates the recognition of the neoplastic form (i.e. IMT) is confusing it does not distinguish the non-neoplastic entities from what would now be classified as inflammatory myofibroblastic tumour.
Treatment of both non-neoplastic and neoplastic form is mainly surgical. May recur locally in cases of inadequate excision. Steroids or other forms of immunosuppression are indicated in IgG4-related disease.