Background: Inflammatory pseudotumor (IPT) is a tumefactive lesion characterized by fibroblastic proliferations and a prominent inflammatory component. It behaves as a locally benign or aggressive lesion, clinically and radiologically mimicking a neoplastic process. Numerous entities can be diagnosed as IPT, from reactive lesions to true neoplasms. The diagnosis of IPT requires further elaboration, and IPT should be distinguished from other similar entities such as inflammatory myofibroblastic tumor and IgG4-related sclerosing disease. Case summary: We report two cases of IPT arising from the head and neck region. One occurred at the orbit and the other at the parapharyngeal space. Histologically, they showed aggregates of myofibroblasts and inflammatory cells. Immunohistochemically, the number of IgG4-positive cells was less than 40% of the number of IgG positive cells, and the myofibroblastic cells were negative for anaplastic lymphoma kinase. The diagnosis was IPT/not otherwise specified. One patient was treated by systemic administration of corticosteroid and had good response. The other, who was treated by local administration of corticosteroid, partially responded and is currently stable with limited disease. Discussion: IPT has been reported to occur in various anatomical sites, most commonly in the lungs. The incidence in the head and neck area is extremely rare. Treatment of IPT is controversial and may involve corticosteroids or surgical resection, or both. Other chemotherapeutic agents and radiotherapy may be considered in steroid-resistant patients. The pathological subtype, safety of resection, and safety of corticosteroid use must be included in the decision-making process for treatment.
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