Presentation
Abdominal pain and right flank fullness and mass feeling on physical exam. Elevated ESR and CRP. No clear history of abdominal trauma or operation.
Patient Data
A 126 × 102 × 108 mm well-defined heterogeneously enhancing mass with significant surrounding inflammatory changes and fluid accumulation is present in the right retroperitoneum that displaces the right kidney, ureter, and bowel loops. There is no sign of local invasion of the adjacent organs, and the IVC is compressed by the mass.
The patient underwent right-sided retroperitoneal mass resection.
Histopathology:
The proliferation of spindle cells with marked pleomorphism in a few foci arranged in storiform and fascicular patterns with mixed inflammatory cell infiltration (lymphocytes, plasma cells, and eosinophils). Some foci of prominent spindle myofibroblastic cells without any atypia intermixed with inflammatory cells are also present.
The neoplastic cells express immunoreactivity as below description:
Actin: positive for myofibroblastic cells
Desmin: positive for myofibroblastic cells
CD45: positive for myofibroblastic cells
S100: negative
Diagnosis:
Inflammatory myofibroblastic tumor
Case Discussion
Inflammatory myofibroblastic tumors, also known as plasma cell granulomas, are rare neoplasms with diverse biological behavior. On histopathology, they are composed of spindle cells (key feature) with a variable infiltrate of inflammatory cells and fibrous tissue.
The most common sites of involvement include the lung, head and neck, mesentery, gastrointestinal tract and retroperitoneum.
Imaging characteristics depend on the organ of involvement. However, overall radiological features of inflammatory myofibroblastic tumors suggest malignant neoplasms, whereas they are not, and these lesions are underdiagnosed entities.
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