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Unusual case of cervical swelling

Beatriz Luzio Vaz, Sara Ferreira
General Pediatrics Department, Hospital de Dona Estefânia, Unidade Local de Saúde S. José, Lisbon, Portugal

Address for Correspondence: Beatriz Luzio Vaz, Hospital Dona Estefânia - Rua Jacinta Marto 8A, 1169-045 Lisboa, Portgal.
Email: anabeatrizvaz@hotmail.com
Keywords : Fibromatosis colli, neonates, sternocleidomastoid muscle
Question:
A 5-week-old male infant, previously healthy, was admitted in the Emergency Department with a one-week right cervical swelling leading to restricted cervical movement. The clinical examination revealed a right cervical swelling of about 1 cm mobile that increased in size with muscle contraction.
A cervical ultrasound showed a fusiform thickening of the right sternocleidomastoid muscle (SCM) approximately 25 x 10 mm, consistent with Fibromatosis Colli. No cervical lymph nodes with pathological dimensions were identified. The infant had a significant improvement with a biweekly motor physiotherapy during 5 months.

Figure 1. Right lateral cervical tumefaction.

What criteria help differentiate Fibromatosis Colli from analogous neck masses in infants?