Extra-Abdominal Desmoid Tumor.

Clinical History

A 50 year-old-man presents with a 1-month history of a rapidly-growing left supraclavicular mass. On physical examination he presents hypoesthesia and dysesthesia of the medial face of the left arm. The patient does not refer weight loss or other symptoms.

Imaging Findings

MRI was performed demonstrating a left low-cervical soft-tissue mass with low signal intensity in T1 and T2 weighted images, intermediate signal in STIR sequence and avid contrast enhancement in pre and post-contrast THRIVE imaging.

Axial images demonstrated focal areas of low intensity inside the lesion that in coronal images corresponded to very low intensity band-like images that crossed the lesion from cranial to caudal.

There is a minimum extension into the left conjunction foramen. The mass contacts with the right anterolateral border of the vertebral body, with a small focal area of cortical erosion.

A CT-guided biopsy was performed.

Discussion

A. Background:
Desmoid tumours (or deep fibromatoses) are a subset of fibroblastic of tumours of muscle, fascia or aponeurosis connective tissue. They present most commonly in adults between 25-35 years of age and are in some cases associated with Cr20 and Cr 8 trisomies [1].

B. Clinical Perspective:
They may be classified into intraabdominal, abdominal and extra-abdominal, depending on the localization of the tumour.

Intraabdominal desmoids may be mesenteric or pelvic. Mesenteric desmoids are associated (though not exclusive) to familial adenomatous polyposis (FAP or Garner syndrome) [1-4].

Abdominal desmoids affect the abdominal wall, predominantly abdominal rectus abdominis and obliquus abdominis muscles, and are affect mainly women either pregnant, in the first year postpartum or on oral contraceptive treatment [1, 2].

Extra-abdominal desmoids affect fasciae and muscles, and affect from most to least frequently: shoulder, thoracic wall, back, hip, and knee. They are very large tumours upon diagnosis (>5 cm), showing rapid growth and are very infiltrative. Desmoids are more aggressive the younger the patient, with a recurrence ratio of 87% in patients younger than 20-years-old, and around 20% in patients over 20-years-old [1].

C. Imaging Perspective:
MRI depicts best extra-abdominal desmoid tumours tissue and its relationship with surrounding structures. It demonstrates a large mass of infiltrative borders that expands along a fascial or muscular axis, often showing a "fascial tail" sign (80%) [1, 3, 5].
Signal is heterogeneous, varying with time depending on tissue composition. Early tumours have higher cellularity and tend to have a higher T2W signal, whilst tardy tumours have a more prominent collagen component and have a lower T2W signal [3-6]. Contrast enhancement tends to be moderate to intense [1, 3]. A typical sign of this type of tumour are longitudinal hypointense fibrous bands present in up to 86% ("black fingers") that correspond to fibrous bundles on pathological examination [1].

D. Outcome.
Management is surgical when possible, despite high recurrence rates. Radiation therapy is useful if this is not effective, also useful in recurrence prevention [2, 4-6].

E. Take home messages.
Extra-abdominal desmoids are very fast-growing infiltrative tumours with aggressive local behavior (not metastatic).
They tend to grow follow fascial and muscular planes, often identifying a "fascial tail".
They are of fibrous composition and usually have low signal in T1W and variable in T2W, with avid contrast enhancement.
Intratumoral fibrous bundles may be seen as lineal hypodense bands following the fascial or muscular axis.

Differential Diagnosis List

Final Diagnosis

Fibroblastic mesenchymal proliferation without cellular atypia: EXTRATHORACIC DESMOID TUMOR

URL:	https://www.eurorad.org/case/13580
DOI:	10.1594/EURORAD/CASE.13580
ISSN:	1563-4086