Calcifying fibrous tumor

Calcifying fibrous tumorstumours, previously known as calcifying fibrous pseudotumorspseudotumours, are rare, benign fibroblastic tumorstumours of the soft tissues.

Epidemiology

It can occur at all ages and there is no strong gender predilection ¹. Fewer than 200 cases have been reported in the English literature ¹.

Clinical presentation

Most cases are asymptomatic, so the tumortumour tends to be found incidentally on imaging ¹. When symptoms are present, they are non-specific and include a palpable painless mass or localizedlocalised pain ¹.

Pathology

Location

Calcifying fibrous tumorstumours can occur throughout the body's subcutaneous or deep soft tissues, with a few sites being more commonly reported ¹:

• stomach (18%) ⁶
• pleura (10%)
• small intestine (9%) ⁵
• peritoneum (7%) ³
• neck (6%) ⁸
• mesentery (5%)

Many other sites have been described, including calcifying fibrous tumortumour of the lung, liver ², and between muscles ⁸. Association with bone is unusual but a case involving the clivus has been reported ⁴.

Classification

The entity is included in the WHO classification of tumorstumours of soft tissue under the fibroblastic/myofibroblastic tumorstumours category.

Macroscopic appearance

It is a circumscribed, nonencapsulated mass and occasionally infiltrates surrounding tissues ¹.

Microscopic appearance

The lesion is composed predominantly of hyalinized stroma with interspersed psammomatous and dystrophic calcifications, fibroblastic spindle cells, and mononuclear/lymphoplasmacytic inflammatory infiltrate ^1,3.

Radiographic features

The appearance depends on the site but in general reflect the histology ^1-7.

Plain radiograph

A mass is present with calcifications.

CT

Partially calcified mass is demonstrated with some contrast enhancement, which progresses on delayed images.

Ultrasound

The mass is hypoechoic with acoustic shadowing and foci of hyperechoic calcifications.

MRI

The mass has the following signal characteristics suggesting fibrosis/collagenous content:

• T1: slightly low signal intensity
• T2: low signal intensity
• T1 C+: relatively hypovascular but with slow progressive enhancement

Treatment and prognosis

Surgical excision is curative. The condition is benign, without reports of mortality; recurrence is rare ¹.

Differential diagnosis

The differential diagnosis is broad and depends on location but includes mesenchymal tumorstumours such as ¹:

• inflammatory myofibroblastic tumortumour
• solitary fibrous tumortumour
• gastrointestinal stromal tumortumour