• Definition: Fibromatosis coli is a rare, self-limiting fibroproliferative condition involving the sternocleidomastoid muscle in neonates and infants.
• Incidence: Occurs in 0.4% to 1.3% of live births (Oh et al., 2001).
• Etiopathogenesis: Postulated to result from birth trauma or ischemic injury leading to fibrotic replacement within the muscle (Yilmaz et al., 2006).
• Clinical Presentation: Painless, fusiform neck mass with or without associated torticollis; usually presents within the first 3–8 weeks of life (Lee et al., 2006).

OBJECTIVE OF THE CASE SERIES:

To illustrate the spectrum of imaging findings in sternocleidomastoid tumor of infancy and to underscore:

• The appropriate use of imaging modalities.
• The central role of high-resolution ultrasonography in early and definitive diagnosis.
• Importance of imaging in differentiating fibromatosis coli from other neck masses (Bianchi & Martinoli, 2007).

CASE SUMMARY:

Case 1 -

• 27 days old female neonate born to a primi para at 39 weeks of gestation with breech presentation after prolonged labour.
• H/o an enlarging Rt sided neck swelling.
• Examination revealed a firm and non-tender swelling on the Right side of the neck. There was no overlying erythema. There was a mild torticollis without facial asymmetry.
• USG revealed- diffusely enlarged Right Sternocleidomastoid muscle with a 2.3 x 1.3 x 1.5 cm sized, fusiform shaped heterogeneously hypoechoic focal lesion having indistinct margins. No abnormal vascularity seen in the lesion.

Case 2 -

• 21 days old female neonate of Primi Para at 40 weeks gestation via a vacuum delivery following induction of labour.
• Ultrasonography of the neck showed an iso to hypoechoic fusiform area in the right sternocleidomastoid muscle, measuring 2.4×1.3×1.4 cm. There was no internal vascularity. Left sternocleidomastoid muscle was normal on sonography.
• Physiotherapy was adviced for the patient.
• On follow-up review after six weeks , the swelling was markedly reduced in size on Ultrasonography and had a slightly hyperechoic appearance.

Case 3 -

• A 29 days old male Infant born to a primipara at 38 weeks gestation with breech presentation , was brought by parents with an enlarging left sided neck swelling.
• Examination revealed a firm and non-tender swelling on the left side of the neck. There was no overlying erythema. There was a mild torticollis without facial asymmetry.
• USG revealed- diffusely enlarged thickening of left sternocleidomastoid muscle with well defined heterogeneously hypoechoic focal fusiform lesion of size 2.1x1.0x1.2 cm. No abnormal vascularity seen within the lesion.

Case 4

• A 1.5 months old female Infant born to a primipara at full term with cephalic presentation with delayed and difficult delivery (forceps used) , was brought by parents with an enlarging right  sided neck swelling.
• Examination revealed a firm and non-tender swelling on the right side of the neck. There was no overlying erythema. There was a mild torticollis without facial asymmetry.
• USG revealed- diffusely enlarged thickening of right sternocleidomastoid muscle with well defined heterogeneously hypoechoic focal fusiform lesion of size 2.5 x 0.99 x 2.42 cm. No abnormal vascularity seen within the lesion.

Imaging Findings

Ultrasonography:

• Modality of choice due to:
  • Non-invasiveness
  • No ionizing radiation
  • Bedside availability
  • High-resolution soft tissue detail (Bianchi & Martinoli, 2007)

• Typical findings:
  • Fusiform enlargement of sternocleidomastoid muscle
  • Hypoechoic to isoechoic echotexture
  • Absence of significant internal vascularity on Doppler (Soyer et al., 1998)
  • Striated muscle pattern preserved in most cases

DISCUSSION

• Differential Diagnosis: Includes lymphatic malformations, Cervical neuroblastoma, Rhabdomyosarcoma, branchial cleft cysts, hemangiomas, and neoplastic lesions. (Yilmaz et al., 2006).
• Role of USG: Early, accurate, and specific; distinguishes fibromatosis coli from other entities without need for sedation or contrast administration (Zawin et al., 1990; Lee et al., 2006).
• Management: Predominantly conservative with physiotherapy and home exercise programmes. Imaging aids in follow-up and reassurance to caregivers. In a few non responsive cases, surgical procedure may be resorted to (Soyer et al., 1998).
• Prognosis: Excellent, with spontaneous resolution by 6–12 months in most cases.
• Fibromatosis colli is a rare entity seen in neonates and infants with diagnosis based on Clinical and Radiological findings. Ultrasonography is the Imaging Modality of choice. Imaging findings on sonography include - Focal/diffuse enlarged sternocleidomastoid muscle with well/ill defined hypo-to-iso-to-hyperechoic mass depending on duration of mass lesion.

CONCLUSION

Sternocleidomastoid tumor of infancy is a benign, self-limiting condition where ultrasonography remains the cornerstone of diagnosis and follow-up. It provides a non-invasive, safe and reliable method to assess and monitor these lesions, guiding clinicians towards conservative management and avoiding unnecessary interventions (Lee et al., 2006; Bianchi & Martinoli, 2007).

REFERENCES

1. Bianchi, S., & Martinoli, C. (2007). Ultrasound of the Musculoskeletal System. Springer.
2. Lee, J. H., Lee, H. K., Park, J. K., Choi, C. G., & Suh, D. C. (2006). Sonographic findings of fibromatosis colli in infants. Journal of Ultrasound in Medicine, 25(5), 601–606.
3. Oh, S. Y., Kim, K. S., & Kim, S. H. (2001). Sonographic diagnosis of fibromatosis colli: Report of 10 cases. Journal of Korean Radiological Society, 44(1), 85–89.
4. Soyer, P., Ruelle, A., Dufour, D., & Vallee, C. (1998). Fibromatosis colli in infants: US imaging. Radiology, 206(2), 355–358.
5. Yilmaz, E., Demir, D., Yildirim, A., & Altuntas, I. (2006). Sternocleidomastoid pseudotumor of infancy: Report of 3 cases and review of the literature. European Journal of Radiology Extra, 57(1), 1–4.
6. Zawin, J. K., Monteagudo, A., & Sherer, D. M. (1990). Fibromatosis colli of infancy: Sonographic diagnosis. AJR American Journal of Roentgenology, 155(5), 1001–1004.