Inflammatory Pseudotumor/Inflammatory Myofibroblastic Tumor of Spleen – A Case Report

Abstract

BACKGROUND: Splenic inflammatory pseudotumor (IPT)/inflammatory myofibroblastic tumor (IMT) is a rare pseudotumor/tumor of unknown origin, which is usually benign, although atypical and aggressive cases have been reported. It is a lesion composed of proliferated myofibroblastic cells (hence IMT by some authors) with admixed pleomorphic inflammatory cells of varying proportions.

CASE REPORT: Herein, we report a case of 61-year-old male patient with ill-defined abdominal discomfort and no other symptoms and signs. Clinical and imaging investigations revealed a mass in the spleen that was equivocally interpreted as secondary neoplasm, although primary neoplasm of the spleen was not excluded by the radiologists. Splenectomy was performed and on gross examination a well demarcated greyish-livid tumor measuring 3.5 cm × 3 cm × 3 cm was discovered. Microscopic examination showed proliferation of loosely arranged spindle cells admixed with inflammatory cells (histiocytes, lymphocytes, neutrophils, eosinophils, occasional plasma cells, and/or plasmacytoid cells) with varying density and multifocal clustering, multifocal hemorrhage, and fibrinoid-like deposition. We performed additional histochemical and immunohistochemical stainings which were consistent with the diagnosis of IPT/IMT. Next-generation sequencing (TruSight Tumor 15) showed common TP53 polymorphism (c.215C>G; p.Pro72Arg) along with several intronic and synonymous single nucleotide variations (SNVs), as well as five low confidence missense SNVs. Sixteen months after the operation the patient has uneventful follow-up.

CONCLUSION: Although the incidence of IPT/IMT is low, awareness of its existence is necessary. The prognosis is favorable following splenectomy in most cases. Careful microscopic examination of the specimen is mandatory, due to possible misdiagnosis. We believe that extensive NGS analysis on archive samples would provide more data about the spectrum of possible genetic changes in lesions like IPM/IMT.