Can the MRI signal of aggressive fibromatosis be used to predict its behavior?

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Abstract

Purpose

Aggressive fibromatosis is an invasive non-metastasizing soft-tissue tumor. Until recently, the standard treatment combined surgery and radiation therapy, but new studies reported that conservative strategies with or without medical treatment could be the best management. The aim of this study was to analyze and correlate the size and MR imaging signal features of aggressive fibromatosis with its behavior in order to choose the best treatment.

Materials and methods

Between March 1985 and December 2005, 27 patients with at least 2 consecutive MRI examinations and no surgery or radiation therapy in between were recorded. There were 9 men and 18 women, and median age was 31 years. They underwent 107 MRI examinations of 47 lesions, 29 of which were medically treated, while the remaining 18 did not receive any drug administration. The size and signal changes of each lesion were studied over time on T2- and/or T1-weighted sequences after injection of contrast medium. RECIST criteria were used for size: only a 30% decrease or a 20% increase in the size of the main dimension was considered significant. We classified the appearance of the signal into six categories in order of increasing intensity and then we established the related variations over time.

Results

The size of 79% of the lesions in the treated group and 82% in the untreated group remained stable. The initial signal of stable lesions or those exhibiting an increase in size was most frequently high. There was a high rate of signal stability over time, whatever the initial signal and size changes. Changes in size were not correlated with the initial MR signal. A decrease in size associated with a decreased signal was observed in three cases exclusively in the treated group.

Conclusion

Fibromatoses are a group of soft-tissue tumors with variable characteristics on MRI, but it is not possible to predict their behavior based on the MRI signal.

Introduction

Aggressive fibromatosis is a soft-tissue tumor composed of normal fibroblastic cells proliferating in an abundant fibrous stroma: it exhibits high invasiveness locally but does not metastasize.

Local aggressiveness is associated with a high-recurrence rate after surgery. Accurate diagnosis and a valid surgical approach are fundamental for the patient's follow-up. This tumor is very challenging for radiologists and clinicians, because its biologic behavior is variable and there is no consensus as to what is the best therapy [1], [2].

The aim of this study was to analyze and correlate signal and size features of aggressive fibromatosis on MRI in order to predict their future behavior and to select the best medical or surgical treatment.

Section snippets

Materials and methods

From March 1985 to December 2005, 125 patients with histological-proven aggressive fibromatosis were seen in our Institute (Radiation Medicine and/or Surgery Departments). Patient's sex and age at presentation, tumor type (primary or recurrent), treatment and outcome were obtained from the hospital electronic patient record system and from Internal Archives. The records of all patients were retrospectively reviewed to determine those who had had an MR examination. Among 125 patients in total,

Results

The 47 nodular tumors were located in the upper extremity (n = 10: shoulder, 7; upper arm, 1; elbow, 1; forearm, 1); lower extremity (n = 18: thigh, 4; knee, 3; calf, 10; foot, 1), the abdominal/thoracic wall (n = 9), the pelvis/buttock (n = 9), and the neck (n = 1).

The results of our series with therapy are presented in Table 1, those without therapy in Table 2.

The rates of variations in size for lesions with therapy or without therapy according to the specified categories (decrease, stability and

Discussion

Aggressive fibromatosis is a benign tumor, characterized by the proliferation of fibrous tissue that disrupts the adjacent intermuscular and soft-tissue planes. It is also called musculo-aponeurotic fibromatosis, desmoid-type proliferation and desmoid tumor. The term “desmoid” is derived from Greek and means a band-like or tendon-like lesion [1], [2], [4].

This lesion accounts for about 0.03% of all neoplasms and less than 3% of soft-tissue tumors [1]. The most common age of incidence is between

Conclusion

Fibromatoses are soft-tissue tumors with an extremely high variability in signal and size. Their behavior cannot be predicted based on their initial MRI signal.

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