Infantile fibrosarcoma of the left upper limb mimicking a hemangioma: A case report

Abstract

Introduction and importance: Infantile fibrosarcoma (IFS) is a rare soft tissue malignancy that primarily affects children under one year of age. Its clinical and radiologic features often resemble benign vascular tumors like hemangiomas, making diagnosis challenging. Early and accurate identification is essential for effective management.

Case presentation: We report a case of a 3-year-old child with a progressively enlarging mass in the left upper limb. Clinical examination revealed a firm, non-pulsatile mass with prominent venous collateral circulation. Doppler ultrasound and MRI findings suggested an infantile hemangioma. Surgical excision revealed a highly vascularized tumor closely associated with the brachial artery and median nerve. Histopathological analysis confirmed infantile fibrosarcoma, characterized by spindle-shaped cells with mild atypia, high mitotic activity, hemosiderin deposits, and significant vascular proliferation. Immunohistochemistry was negative for myogenin, cytokeratin, desmin, CD68, and TLE1.

Clinical discussion: This case underscores the diagnostic challenge posed by IFS, which can closely mimic infantile hemangioma on imaging. MRI findings suggested but did not confirm the diagnosis. Histopathology remains the definitive method for diagnosis. Multidisciplinary management-including surgical resection and, when indicated, chemotherapy-is essential for optimal outcomes.

Conclusion: IFS should be considered in the differential diagnosis of congenital soft tissue masses, particularly when atypical features are present. Definitive diagnosis relies on histopathological and immunohistochemical evaluation. Multidisciplinary management plays a critical role in ensuring favorable clinical outcomes.

Keywords: Case report, infantile fibrosarcoma; Hemangioma; Left upper limb.

Fig. 1

Swelling of the left arm with venous collateral circulation.

Fig. 2

MRI of the left upper limb. T2-magnetic resonance imaging of the infantile fibrosarcoma demonstrating an ovoid mass with moderate hypersignal, traversed by vascular structures (a), which enhances in an intense and homogeneous manner after injection of gadolinium (b).

Fig. 3

Macroscopic characteristics of the tumor after removal.

Fig. 4

Histopathological appearance of infantile fibrosarcoma. A richly vascularized mesenchymal proliferation (a), made of spindle cells resembling fibroblasts and presenting slight atypia and significant mitotic activity (b) the tumor tissue contained deposits of hemosiderin and dotted with chronic inflammatory infiltrate, composed of lymphocytes, plasma cells and some histiocytes (c). The tumor infiltrated the surrounding adipose and connective tissue (d).