Inflammatory pseudotumor: a diagnostic dilemma in cytopathology

Inflammatory pseudotumor (IPT) is a rare space-occupying lesion of unknown etiology that can mimic malignancy on clinicoradiological and pathological examination. A review of the cytopathology archives at The Johns Hopkins Hospital identified 12 cases from eight patients with histologically proven IPT (lung, seven patients; liver, five patients). There were six men and two women with an age range of 28-84 yr (mean age, 59 yr). Presenting complaints of IPT of the lung included shortness of breath and hemoptysis, and in cases of IPT of the liver complaints included abdominal pain and elevated liver function tests (LFTs). All cases were found to have mass lesions suspicious for a neoplasm on radiographic examination. Cytological specimens consisted of fine-needle aspiration (FNA; seven specimens) and bronchial brush/wash (five specimens). Diagnostic accuracy of cytology for IPT was low (5/12, 42%). IPT showed hypercellular smears (on FNA) with an admixture of various cell types including inflammatory cells with predominance of plasma cells, fibroblastic proliferation, granulation tissue formation, and atypical-appearing histiocytes with enlarged nuclei and intranuclear inclusions. Fibroblastic proliferation with mitoses may mimic mesenchymal neoplasms. Cytomorphology is nonspecific and IPT usually is a diagnosis of exclusion.