Incisional and Excisional Biopsy

An incisional biopsy was initially performed on the day of presentation.  Four days after the incisional biopsy, the patient presented with a larger lesion with a non-healing or fungating biopsy site (Figure 4).

Within one week, the lesion was completely excised.

Histological examination reveals a highly cellular fibrous lesion with a focal myxoid background.  The fibroblasts are eosinophilic with plump and vesicular nuclei and are arranged in elongated fascicles with focal areas of storiform pattern as shown below.  

The lesion infiltrates the adjacent structures, including bone, muscle and surrounding connective tissue.  Mitotic figures are present but scant.  There is no evidence of pleomorphism.  

Low power (x100) histology shows fibroblasts arranged in elongated fascicles with focal areas of storiform pattern.

High power (x200) histology shows fibroblasts arranged in elongated fascicles.

The surgical specimen was interpreted at Children’s Hospital by Dr. Kathy Patterson; the histology of the surgical specimen is similar to that of the incisional biopsy.  Immunohistochemistry markers are positive with smooth muscle marker HHF35, but negative with desmin, myogenin, and S-100 proteins.  The IHS marker profile combined with the H&E stain are consistent with aggressive fibromatosis.