Omental‐mesenteric inflammatory pseudotumor. Cytogenetic demonstration of genetic changes and monoclonality in one tumor

Background. Extrapulmonary inflammatory pseudotumor (plasma cell granuloma) is an uncommon lesion in adults and children, and little is known either of its etiology or clinical characteristics. However, it remains a significant source of morbidity to patients and confusion to clinicians. Methods. Case reports are presented of three patients with intraabdominal inflammatory pseudotumor who recently underwent surgery. A review of the recent world literature is also presented. Clinical and laboratory characteristics of omental‐mesenteric inflammatory pseudotumor are reviewed along with a discussion of its etiology. Results. Cytogenetic data from cells of one patient show a derivative chromosome evolved from a translocation between the long arm of chromosome 2 and the short arm of chromosome 9 [(2;9) (q1,3;p2,2)]. Conclusions. The lesion is monoclonal, and genetic changes may play a crucial role in the development of this neoplasm. Omental‐mesenteric inflammatory pseudotumor appears to represent a distinct clinicopathologic entity as a benign neoplasm in children. Cancer 1994; 73:1433–7.