Ossifying fibromyxoid tumour

Ossifying fibromyxoid tumour (OFMT) is a rare and distinct type of soft tissue tumour that was first described in 1989. It is characterized by a combination of fibrous, myxoid, and ossifying components. The tumour is usually benign, but in rare cases, it can be malignant.

Clinical Presentation

Patients with OFMT often present with a slow-growing, painless mass. The tumour is most commonly found in the deep soft tissues of the extremities, particularly the thigh, but it can also occur in the trunk, head, and neck. The age of patients at the time of diagnosis ranges from 15 to 83 years, with a median age of 50 years. There is a slight male predominance.

Pathology

Histologically, OFMT is characterized by a lobulated growth pattern with a fibrous pseudocapsule. The tumour cells are small and round to spindle-shaped, with a moderate amount of eosinophilic cytoplasm. The nuclei are round to oval and have a finely granular chromatin pattern. The tumour stroma varies from fibrous to myxoid, and there is often a peripheral rim of metaplastic bone.

Diagnosis

The diagnosis of OFMT is based on the characteristic histological features, but it can be challenging due to the rarity of the tumour and its histological overlap with other soft tissue tumours. Immunohistochemistry can be helpful in the diagnosis. The tumour cells are usually positive for vimentin, S-100 protein, and CD34, and negative for desmin and smooth muscle actin.

Treatment and Prognosis

The treatment of choice for OFMT is surgical excision with clear margins. The prognosis is generally good, with a low rate of local recurrence and distant metastasis. However, malignant cases can have a more aggressive course.

See Also

• Soft tissue tumour
• Fibromyxoid sarcoma
• Osteosarcoma