Giant cell fibroblastoma (GCF) is a rare soft tissue tumour of childhood which was first described by Schmookler and Enzinger.

This rare mesenchymal neoplasm is classified as a fibrohistiocytic tumour of intermediate malignancy owing to its propensity for local recurrence, but metastases have never been reported.Giant cell fibroblastoma. A distinctive, recurrent tumor of childhood. Am J Surg Pathol. 1987;11(4):263-71

It has been considered by some authors as a juvenile variant of dermatofibro- sarcoma protuberans.Giant cell fibroblastoma. A juvenile form of dermatofibrosarcoma protuberans. Cancer. 1989 Nov 15;64(10):2154-61.

Age and sex:  It appears in children in the first decade of life. Most cases occur before the age of 5 years. Rare cases have been reported in adults. There is a male predominance.

Site: This slowly enlarging painless nodule is located in the superficial soft tissue, and has been described in the back, thigh and chest.

Macroscopic features: Uncapsulated gray-white lesion, usually less than 5cm in diameter. It is partly gelatinous with myxoid foci and there is no necrosis or hemorrhage.

Microscopic features:  There are 2 distinct patterns: 1) The solid or cellular foci composed of spindled and multinucleated cells present in a fibrocollagenous or myxoid background and  2) the angiectoid or sinusoidal foci composed of pseudovascular spaces lined by neoplastic cells.
The lesion infiltrates the deep dermis and subcutis and encircles adnexal structures.

Immunohistochemistry:  The tumour stained diffusely for vimentin and CD34. The cells are negative for S100 protein, desmin, muscle specific actin and factor VIII.

Differential Diagnosis: DFSP; dermatofibroma; vascular tumours ; neurofibroma, meningothelial hamartomas, lymphangiomas.
Relationship of GCF with dermatofibrosarcoma protuberans (DFSP):  DFSP and GCF demonstrate the same immunohistochemical findings and share the same cytogenetic abnormalities.  A translocation (17; 22) (q22; q13) has been described in both entities. Cases of GCF with DFSP-like areas and the recurrence of GCF as frank DFSP and vice versa suggests that the two lesions may be related. Histogenetic relations between giant cell fibroblastoma and dermatofibrosarcoma protuberans. CD34 staining showing the spectrum and a simulator.Am J Dermatopathol. 1998 Aug;20(4):339-45

GCF should not be overdiagnosed as a soft tissue sarcoma. Eg: myxoid malignant fibrous histiocytomas, myxoid liposarcomas, malignant nerve sheath tumors, and other mesenchymal sarcomas. These tumours usually occur in adults.

Clues for the diagnosis of giant cell fibroblastoma:  Superficial location;  Lack of intricate vasculature ;  Multinucleated cells along the pseudovascular spaces. 

Treatment of choice is local excision with tumour free margins. Local recurrence   is probably related to incomplete resection of the tumour.