[A case of multifocal inflammatory pseudotumor of the liver]. / Su un caso di pseudotumore infiammatorio multifocale del fegato.

INTRODUCTION: The inflammatory pseudotumor (IPT) of the liver is a tumor-like lesion of unknown etiology and pathogenesis. Non infectious by definition the lesion is considered to be a long-lasting inflammatory process. CASE: In this report we describe a multifocal liver pseudotumor of a 52 year man who underwent a selective hepatectomy for a clinical and radiological suspicion of a liver cell carcinoma. RESULTS: Grossly the masses consisted of rubbery grey-yellowish nodules well-circumscribed from the liver parenchyma. Histologic examination revealed a double shaped cellular population surrounded by a thin rim of collagen fibres. The main population consisted of fibroblasts and histiocytes with no atypias or mitoses, arranged in a storiform or fascicular pattern; the second population consisted of a mixed population of lymphocytes, plasma cells, neutrophils and monocytes. Fibroblasts and histiocytes revealed diffuse positive immunostaining for vimentin and focal immunostaining for cytokeratin and desmin. The histiocytes were also CD68, CD18, CD14 and CD4 positive. CONCLUSIONS: Our case reveals same histological and immunohistochemical features already reported in literature. Primary and metastatic tumors involving the liver need to enter in the differential diagnosis but IPT lacks features of malignancy and the cell population is mixed. Although there is no specific marker for this lesion in cases featuring malignancy immunohistochemistry may be useful for a differential diagnosis: S-100 in cases of neurofibrosarcomas, actin and myosin for rhabdomyosarcomas, cytokeratin for epithelial tumors.