Age / Sex : 62 / M

Desmoplastic Fibroblastoma

Discussion

Findings:

Transverse ultrasonography of the left shoulder show a well-defined, hypoechoic mass located in the intermuscular space.

Coronal T1-weighted and T2-weighted fat-suppressed MR images of left shoulder show well-circumscribed intermuscular soft-tissue mass of low signal intensity on both sequences.

Sagittal T2-weighted image shows a low signal intensity mass with a border with clear margins.

Coronal fat suppressed T1-weight MR image after gadolinium administration shows no significant enhancement of the soft tissue mass.
 

Differential Diagnosis:

1.     Demoid tumor

2.     Nodular fasciitis

3.     Fibroma of the tendon sheath

4.     Sclerotic fibroma
 

Diagnosis: 

Desmoplastic Fibroblastoma (Collagenous fibroma)
 

Discussion:

Desmoplastic fibroblastoma (Collagenous fibroma) is a rare fibrous soft tissue tumor, characterized by stellate- and spindle-shaped fibroblastic cells dispersed in densely fibrous to fibromyxoid matrix with hypocellularity. This tumor classically presents a painless, firm and slowly growing mass.

These tumors show predilection for male patients (5:1) and have a peak incidence in the fifth and sixth decades of life.

On MRI, the lesion shows a mass with low signal on both T1- and T2-weighted images. Gadolinium-enhanced T1-weighted images shows non-enhancing areas within the mass. The areas of low signal intensity on both T2- and contrast enhanced T1-weighted images correspond with a hypocellular component with abundant collagen fiber.

The radiological differential diagnoses includes demoid tumor, nodular fasciitis, fibroma of the tendon sheath, giant cell of the tendon sheath, calcifying fibrous pseudotumor, sclerotic fibroma, and other malignant neoplasm such as low grade fibromyxoid sarcoma.

Treatment of desmoplastic fibroblastoma is surgical excision with no reported incidence of local recurrence or metastases.

References:

1. Bonardi M, Zaffarana VG, Precerutti M. US and MRI appearance of a collagenous fibroma (desmoplastic fibroblastoma) of the shoulder. J Ultrasound. 2013 Nov 19;17(1):53-6.

2. Yamamoto A, Abe S, Imamura T, Takada K, Enomoto Y, Harasawa A, Matsushita T, Furui S. Three cases of collagenous fibroma with rim enhancement on postcontrast T1-weighted images with fat suppression. Skeletal Radiol. 2013 Jan;42(1):141-6.

3. Walker KR, Bui-Mansfield LT, Gering SA, Ranlett RD. Collagenous fibroma (desmoplastic fibroblastoma) of the shoulder. AJR Am J Roentgenol. 2004 Dec;183(6):1766.