Fibrosing inflammatory pseudotumor

Abstract

Fibrosing inflammatory pseudotumor is a non-specific inflammatory process of uncertain etiology. Histology of this lesion shows a polymorphous infiltrate with plasma cells, lymphocytes and eosinophils with a significant reactive fibrovascular component [Sung MV, Kim K, Lee C, Moh JH, Kim WH, Han MH. Fibrosing inflammatory pseudotumors of the central skull base. Laryngoscope 1997;107(12):1651–5; Helemberger RC, Mancuso AA. Wegener granulomatosis if the Eustachian tube and skull base mimicking a malignant tumor. AJNR 1996;17:1785–90]. This reactive fibroinflammatory process can be locally aggressive and mimic a malignant lesion. It has been described involving the skull base, orbit, ear, the parotid glad, paranasal sinuses and the pterygomaxilary space. The Tolosa Hunt syndrome and the orbitary pseudotumor, probably, represent a clinical variant of this process. Central skull base involvement is an unusual form of inflammatory pseudotumor, fewer than 30 cases have been described in the literature until now. Common clinical manifestations are pain and a variety of neurological dysfunctions of the cranial nerves specially nerves VII, IX, X and XII. Imaging studies, computed tomography (CT), magnetic resonance imaging (MR) and positron emission tomography (PET) demonstrate the extent of the lesion but cannot rule out a malignant process [Sung MV, Kim K, Lee C, Moh JH, Kim WH, Han MH. Fibrosing inflammatory pseudotumors of the central skull base. Laryngoscope 1997;107(12):1651–5; Helemberger RC, Mancuso AA. Wegener granulomatosis if the Eustachian tube and skull base mimicking a malignant tumor. AJNR 1996;17:1785–90; Han MH, Je GC, Myung SK, Kee HC, Kwang HK, Kyung MY. Fibrosing inflammatory pseudotumors involving the skull base: MR and CT manifestations with histopathologic comparison. AJNR 1996;17:515–21]. However, biopsy results are negative with chronic inflammation without any evidence of neoplastic cells. We present a case of fibroinflammatory pseudotumor of the central skull base with paralyses of lower cranial nerves, including nerves IX, X and XII.