Repetitive trauma-induced extra-nuchal-type fibroma

Abstract

A nuchal-type fibroma is a rare, benign fibrous tumour that typically occurs in the posterior neck along the midline, but can occur in extra-nuchal locations, most commonly in the back, shoulder and face. We present a biopsy-proven case that arose as a result of heavy gym-related activities. In particular, a heavy barbell was rested on his vertebral prominence at the level of C7/T1 during leg squatting. Repetitive trauma as a cause for extra-nuchal-type fibromas has been sparsely reported, but we suggest that sustained high pressure is an additional required feature. Although this lesion was in the posterior neck, it was contained entirely within the subcutaneous tissues without involvement of the nuchal ligament. Hence, it was considered an extra-nuchal fibroma. A description of key ultrasound and MRI imaging characteristics are provided to assist in making the diagnosis, along with a review of the current literature and a discussion of differential diagnoses.

Keywords: Gardner; Nuchal fibroma; Repetitive trauma.

Fig. 1

A T1 image of the cervical spine in the sagittal plane. B T1 with contrast enhancement. The nuchal-type fibroma overlies the C7 and T1 spinous processes and is marked with white arrows. The ligamentum nuchae is indicated with a white asterisk, and ends at the spinous process of C7. Note the lack of capsule and high T1 and T2 streaks, consistent with adipose tissue, interspersed within low signal regions, representing collagenous fibrous tissue

Fig. 2

A T2 axial image and B T1 axial image between the C7 and T1 spinous processes demonstrating the low signal nuchal-type fibroma in the subcutaneous tissues marked by white arrows extending up to the dermis. There is no evidence of invasion into the deeper tissues beneath the deep fascial layer, as indicated by the dark T1 line between the white asterisks

Fig. 3

Ultrasound image taken transverse across the level of the T1 spinous process. The mass is seen within the subcutaneous tissues but is poorly encapsulated. It demonstrates diffusely high echogenicity with slight heterogeneity. On Doppler imaging, no colour flow was seen

Fig. 4

Core biopsy sample, H&E stain. Note the thick bundles of haphazardly organised collagen fibres, encasing the lobulated adipose tissue (arrows), and relative scarcity of nuclei (asterisks). Nerve and skeletal muscle involvement is not seen in this specimen

Fig. 5

Core biopsy sample, Verhoeff-Van Gieson elastin stain. A delicate network of black-stained elastic fibres was seen between the collagen fibres (arrows), which comprise the majority of the sampled tissue