Fibromatosis colli or pseudotumour of sternocleidomastoid muscle, a rare infantile neck swelling

Fibromatosis Colli: A Thorough Description of Its MRI Characteristics and a Review of the Literature

“…Whilst the physiopathology of FC is not yet fully elucidated, it has been theorised that it is linked to birth trauma, resulting in obstructed venous outflow from the muscle [1]. This, in turn, leads to necrosis and fibrosis of the muscle fibres, resulting in muscle strain [1]. The theory of venous outflow obstruction has some evidence in experimental studies and canine models [4].…”

“…Other theories link the pathology to the use of forceps, a breech position during birthing or primiparous births [4]. A competing explanation links the pathology to a sternocleidomastoid injury due to in-utero mispositioning of the foetuses' head [1]. There have also been reports that the lesion appears in utero in 25% of cases, as well as reports of the condition in infants having been born by caesarean section [4].…”

“…The treatment for this disease is generally physiotherapy, with the pathology tending to resolve within 2 years, though in some cases surgery is required [1,4,6,[13][14][15][16].…”

“…Fibromatosis colli (FC) is a rare pseudotumor of the sternocleidomastoid muscle, with an incidence of 0.4% and a higher incidence in males (Alrashidi, 2022) [1]. It is currently classified as a benign myofibroblastic tumour according to the 2020 WHO classification [2].…”

“…The pathology seems to have a higher incidence in males and is the most common cause of perinatal neck masses [4]. This pathology has been reported to often be associated with birth trauma, with authors theorising that the fibrosis and subsequent shortening of the sternocleidomastoid muscle may occur after haemorrhage [1,3]. FC has been reported to favour the right side in three quarters of cases, with its growth continuing for a few weeks after birth [3].…”