Fibromyxoid sarcoma in the retroperitoneum: A case report

Abstract

Rationale: Low-grade fibromyxoid sarcoma (LGFMS) is a pathological type of fibrosing fibrosarcoma that appears as a distinctive soft tissue masse with bland histological features. It is mostly located in the deep soft tissues of the extremities. Computed tomography (CT) plays an important role in diagnosing fibrosing fibrosarcoma in the abdomen. To date, several studies in the literature have reported on CT features of LGFMS.

Patient concerns and diagnoses: We report another case of LGFMS, which presented with certain unique CT feature. The anterolateral region and the wall of the cystic nodules showed gradual enhancement and several nourishing vessels were seen after contrast administration. These imaging features were consistent with the histologic findings of LGFMS.

Interventions and outcomes: The patient underwent tumorectomy and implantation of radioactive implants. Two years after the operation, 1 metastasis mass occur in the right psoas major.

Lessons: These CT features in LGFMS may be useful to assess the histological characteristics of LGFMS to facilitate preoperative diagnosis in the clinical setting and provide the supplemental imaging knowledge for future studies.

Figure 1

Contrast-enhanced computed tomography (CT) performed on a 48-year-old male with low-grade fibromyxoid sarcoma (LGFMS). A, The axial CT image showed a small hypoisodense area (white arrow) and intralesional septa (small black arrow). B, A nourishing vessel was found in the lesion (white arrow). C, The fibrous septa (small black arrow) and the hypoisodense area (white arrow) displayed gradual enhancement.

Figure 2

A The histologic findings showed collagenous nodules with low cellularity (H&E, ×40) (black arrow). B, Immunohistochemical analysis displayed strong and diffuse staining for vimentin (×40).

Figure 3

Two years after the operation, ultrasonography and abdominal computed tomography (CT) were performed. A, Ultrasonography depicted a heterogeneous low echo mass near the right psoas major (white arrow). B, The axial CT image on the venous phase indicated a mass with isohyperdense parenchyma (white arrow).