Desmoid-Type Fibromatosis (DF)

Diagnosis

Desmoid-Type Fibromatosis (DF)

Diagnosis

Desmoid-Type Fibromatosis (DF)

History

Young boy with left radial lesion discovered post-trauma.

Findings

Lobulated lytic lesion arising for left distal radius, with bone destruction and soft tissue invasion. Uptake is mild to moderate, with central hypoactive regions.Linear uptake regarding the left proximal radius.Otherwise normal study.

Discussion

Fibroblastic and myofibroblastic proliferations encompass a large number of pathologies, some benign, some locally aggressive and some true neoplasms. Fibromatosis can also be classified as superficial (fascial) or deep (musculoaponeurotic). Desmoid-type fibromatosis (DF) also called aggressive fibromatosis and desmoid tumor represents around 60% of fibrous tumors in children. In addition to DF, other fibroblastic/myofibroblastic are, among others, infantile myofibromatosis, inflammatory myofibroblastic tumor, fibrosarcomas. It may be associated with Gardner's syndrome.
DF is characterized by a deep-seated monoclonal proliferation of myofibroblasts. While it does not metastasize, it can be locally invasive and refractory to treatment with recurrence. DF can be found in any part of the body but most often in the extremities or in the abdominal cavity.
Pathological findings are a proliferation of spindle-shaped fibroblasts without atypia and with rare mitosis. Immunochemistry will reveal positivity for vimentin, smooth muscle actin and β-catenin.
In patient with small tumors a wait-and-see approach is recommended. Surgical resection is possible but recurrence rates have been reported up to 40% of patients. Systemic treatment options include non-steroidal anti-inflammatory agents, hormonal therapy, interferon, chemotherapy and more recently tyrosine kinase inhibitors.
FDG PET/CT imaging of fibromatosis includes a few case reports and a few series of patients with either musculoskeletal lesions including chest wall involvement or intraabdominal disease. Uptake is generally mild to moderate, with a mean SUVmax around 3.Uptake is also heterogeneous due to the presence of collagen and more cellular areas. However, in some occasion, hypermetabolism was significant, mimicking sarcoma. Some patients have been imaged again post chemotherapy or tyrosine kinase inhibitors, with reduction in uptake in responders.

Key points

Differential Diagnosis:
Esinophilic Granuloma
Giant Cell Tumor
Aneurysmal Bone Cyst
Traumatized Unicameral Bone Cyst.Sarcoma

References

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