There may be a slight male predilection. It typically presents a few weeks after birth.
Presentation is usually with torticollis and is most frequently related to birth trauma (e.g. forceps delivery) or malposition (e.g. breech) in the womb. On clinical examination, there may be a growing, hard neck mass.
The importance of fibromatosis colli, above all else, is that it must be recognized for the benign lesion that it is. It is unilateral in most cases. It has been proposed that birth trauma leading to hemorrhage as a predisposing factor eventually results in fibrosis.
The right sternocleidomastoid muscle is more commonly affected (73% of the time).
Ultrasound is the imaging modality of choice. The sternocleidomastoid muscle is diffusely enlarged (but most involves the muscle belly) to assume a fusiform/ellipsoid shape/thickening with resultant shortening, therefore the chin is turned away from the affected side (the mastoid process is drawn inferiorly towards the ipsilateral head of clavicle). Echogenicity may vary in the affected fibrotic regions. Spectral Doppler interrogation may reveal a high resistance waveform. The enlarged area often moves synchronously with the rest of the sternocleidomastoid on real-time sonography 1, smoothly blending with the unaffected fibers. A discrete mass should not be seen. The presence of hyperechoic calcific foci suggests previous hemorrhage.
Typically shows a diffusely enlarged sternocleidomastoid that is isoattenuating to normal neighboring musculature. Adjacent fat planes are well preserved. At times, calcification may be present 2.
Treatment and prognosis
It is a self-limiting condition and usually resolves within 4-8 months 3 and requires no more than physiotherapy.
For a general differential see: differential diagnosis of pediatric cervical lesions.
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- 3. Crawford SC, Harnsberger HR, Johnson L et-al. Fibromatosis colli of infancy: CT and sonographic findings. AJR Am J Roentgenol. 1988;151 (6): 1183-4. AJR Am J Roentgenol (citation) - Pubmed citation
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