Diversity of imaging findings in fibromatosis colli

<p>[Background] Fibromatosis colli is an infantile neck mass resulting in torticollis. Previous studies have reported numerous image findings linked to fibromatosis colli and that they may depend on the patient’s age at examination.</p><p>[Purpose] We aimed to reveal the diversity of ultrasonogram (US) and magnetic resonance image (MRI) findings by assessing the patient’s age (in days) at examination.</p><p>[Material and Methods] We enrolled 13 infantile (6 male; 7 female) patients clinically diagnosed with fibromatosis colli in this retrospective study. US was performed in 12 cases (one examination in eight cases, two examinations in one case, three examinations in one case, and four examinations in two cases) and MRI was performed in five cases (one examination in three cases and two examinations in two cases). Using US, we evaluated the maximum diameter in the long axis and echogenicity of the sternocleidomastoid, discontinuity of the muscular bundle, and presence/absence of hypoechoic lesion in the sternocleidomastoid. Using MRI, we evaluated the diameter of the sternocleidomastoid, patchy or diffuse hyperintensity areas on T2-weighted images (T2WI), and swollen sternal or clavicle head of the sternocleidomastoid. We assessed the imaging findings’ time course in four and two cases using several US and MRI examinations, respectively.</p><p>[Result] We observed hyperechoic sternocleidomastoids on US in all cases (12/12). Discontinuity of the muscular bundle was seen in 4/12 cases; hypoechoic lesion in the sternocleidomastoid was seen in 8/12 cases. In two/five and three/five cases, we observed patchy and diffuse hyperintensity on T2WI, respectively. The sternal head was swollen in four/five cases and the clavicle head was swollen in one/five case. No correlation was observed between the diameter of the sternocleidomastoid and patient age on US examination (R = 0.111). Echogenicity of the sternocleidomastoid was normalized in two/four cases following several US examinations. In one/one and two/four cases, disappearance of discontinuity of the muscular bundle and hypoechoic lesions were observed, respectively.</p><p>[Conclusion] Our study shows various findings on US and MRI during the clinical course.</p>