Unusual localization and aggressive progression of large infantile fibrosarcoma

Abstract

Infantile fibrosarcoma is a very rare soft tissue tumor in infants and children most commonly located in extremities. It constitutes less then 1 percent of all childhood cancers. Prognosis and clinical course of it is relatively good compared to adult forms. Local recurrence is common but metastasis is infrequent. In this case report we present infantile fibrosarcoma with relapse and lung metastasis despite neoadjuvant chemotherapy, pelvic reconstruction surgery with wide surgical excision and adjuvant chemotherapy protocol. The patient was a 2-year-old girl at the time of diagnosis, and there was a huge mass in pelvic region. After neoadjuvant chemotherapy, type 1 pelvic resection and pelvic reconstruction with bone cement performed. The patient presented with relapse and lung metastasis 6 months after the surgery. This is the first report of pelvic infantile fibrosarcoma with pelvic resection surgery. This case suggests that these tumors may exhibit unpredictable clinical behavior.

Keywords: Chemotherapy; Distant metastasis; Infantile fibrosarcoma; Pelvic region; Surgical treatment.

Fig. 1

Magnetic resonance imaging (MRI) revealed a solid heterogeneous mass in the right hemipelvis measuring approximately 12×8×8 cm which is centrally cystic and necrotic. The lesion is hypointense in T1-weighted non-fat-suppressed axial images (TR:400.0/TE:10.0) (A) and had peripheral contrast in T1-weighted contrast enhanced fat-suppressed coronal images (TR:497.0/TE:11.0) (B).

Fig. 2

Postcontrast coronal T1 (TR:497.0/TE:11.0) (A) and T2-weighted fat suppressed axial (TR:4220.0/TE:54.0) (B) MR images revealed that there was minimal regression in the tumor after neoadjuvant chemotherapy.

Fig. 3

A: Intraoperative photograph of mass B–C: Gross appearance of the tumor after excision and photograph of reconstruction. Polypropylene mesh was used to increase hip stabilization and prevent a possible hip dislocation.

Fig. 4

Postoperative pelvis antero-posterior and lateral radiographs. Following type 1 internal hemiplevectomy with wide margins, cementation was applied to fill the iliac defect and stabilization of the cementation was achieved by lumbopelvic, iliopubic and ilioischial fixation with plates and screws.

Fig. 5

A: Macroscopic poorly circumscribed, lobulated, with tan-gray, fleshy cut surface and necrosis, B: The tumor is infiltrated adjacent soft tissue with irregular margins and zonal necrosis (H&Ex40) C: The tumor is composed of uniform, moderately atipical spindle cells with oval to fusiform nuclei (H&Ex200) D: Increased mitotic figures (H&400) E: Focal positivity with SMA (x200) and focal positivity with desmin (x200).

Fig. 6

A: Thorax CT revealed widespread multiple metastatic lesions in both lungs at postoperative 6 months. B: Image of axial CT angiography showed border of irregular mass compatible with relapse (black arrow). The external (blue arrow) and internal iliac (red arrow) arteries were invaded by the mass.