A case of inflammatory pseudotumor of the cheek

Abstract

Inflammatory pseudotumor is a benign disease that is histopathologically characterized by the presence of non-specific chronic inflammatory cells. Clinically, these tumors often show neoplastic growth, and it is difficult to differentiate them from neoplastic lesions by imaging findings alone. Inflammatory pseudotumors have been found to occur at various sites, but are rarely found in the head and neck region. Although surgical excision and steroid therapy are effective, no evidence has been established yet. We report a case of an inflammatory pseudotumor that occurred in the cheeks. A 51-year-old man with right cheek swelling and pain had visited a local physician a month earlier and antibiotics had been prescribed. Since the symptoms did not improve, CT was performed as an aid to diagnosis, and an abscess or neoplastic lesion was suspected in the cheek. Cytologic examination revealed many neutrophils and histiocytes, but no evidence of malignancy. MRI showed an abscess in the masseter muscle with spread of the inflammation to the surrounding tissues. Antibiotics and steroid therapy were initiated and the swelling diminished in size. When the steroid was withdrawn, the swelling enlarged again. Therefore, inflammatory pseudotumor, non-epithelial tumor, and malignant lymphoma were considered in the differential diagnosis. An excisional biopsy was performed and the diagnosis of inflammatory pseudotumor was established. A subset of the cells was positive for IgG4, but there was no definitive evidence of IgG4-related diseases. Treatment of inflammatory pseudotumors includes surgical resection, steroid therapy, radiation therapy, chemotherapy; the efficacy of steroid therapy has been reported for inflammatory pseudotumors in the head and neck region. Although evidence has still not been established, steroid maintenance therapy is effective for preventing recurrence. The patient is currently receiving steroid maintenance therapy on an outpatient basis, and has shown no evidence of recurrence of the inflammatory pseudotumor.