Radiology quiz

ALAN NAZERIAN, MD

aSpring 1997

HISTORY:  A previously healthy four-week-old male presents with torticollis and a mass in the neck. There was no history of trauma. He was afebrile and had a normal white blood cell count. Ultrasound images of the neck are shown in Figures 1 and 2

FIGURE 1. Transverse (above) and longitudinal (below) ultrasound images of the right sternocleidomastoid muscle (arrows)

QUESTIONS:  What are the ultrasound findings? What are the neck masses which occur in the neonate? How should this patient be treated?

FIGURE 2. Longitudinal ultrasound images of both the right and left sternocleidomastoid muscle (arrows).

RADIOLOGIC FINDINGS:  The ultrasound exam demonstrates enlargement of the right sternocleidomastoid muscle (Figure 1) which is most apparent when comparison is made with the normal side (Figure 2). It is slightly heterogeneous in echo texture and shows no evidence of calcification or cyst. There is no extension of mass beyond the confines of the sternocleidomastoid, and the surrounding tissues appear normal. No adenopathy was seen, and the thyroid gland was normal. Contrast-enhanced CT scan of the neck in another patient is shown in Figure 3. The right sternocleidomastoid is enlarged, homogeneous in appearance and iso-attenuating with muscle, and there is mass effect on the internal jugular vein.

Axial contrast-enhanced CT image of the neck showing the right sternocleidomastoid muscle (large arrow) and right and left internal jugular veins (small arrows).

DIAGNOSIS:  Fibromatosis colli (sternocleidomastoid pseudotumor of infancy).

Discussion

Fibromatosis colli (FC), also called pseudotumor of infancy, is a nonneoplastic condition involving the sternocleidomastoid muscle (SCM) occurring in 0.4% of all neonates. It occurs more commonly on the right side and is more frequently seen in males. The pathophysiology is not clear, but is felt to be related to prenatal and antenatal events. Birth injury has been implicated, and it is associated with difficult deliveries, including forceps deliveries. Breech birth, clubfoot and developmental hip dysplasia are also associated. Patients are previously healthy and usually present between two and four weeks of age with a neck mass along the distribution of the SCM. Torticollis is present in a minority of cases. The mass is firm, and there may be shortening of the affected muscle. Constitutional symptoms and overlying skin changes are absent. Fibromatosis colli is suspected on clinical grounds. Imaging is performed to confirm the diagnosis and, most importantly, to distinguish FC from a congenital anomaly or malignant tumor. Table 1 lists other neck masses that occur in the neonate.

Ultrasound, CT and MRI have all been used in the evaluation of FC. In a series of 17 patients reviewed by Dr. John Maddalozzo at Children's Memorial Hospital, ultrasound was 100% sensitive in detecting the condition. Because ultrasound is low in cost, does not require sedation and is free of ionizing radiation, it is an ideal examination method. Scanning is performed in longitudinal and transverse planes with emphasis made on comparison with the unaffected side. The thyroid gland and vascular structures in the neck are also well evaluated.

Fibromatosis colli is usually seen on ultrasound as fusiform enlargement of the SCM with smooth margins and without a discrete mass. While there may be displacement of the trachea, jugular vein or carotid artery, patients are usually not symptomatic. Heterogeneity of echo texture is usually present. There is no calcification, cystic structure, discrete mass, vascular abnormality, extension beyond the confines of the muscle, or significant regional adenopathy; if any of these findings are present, the diagnosis of FC cannot be established and alternative diagnoses must be considered. Both CT and MRI are excellent methods for further evaluation if necessary.

Treatment of FC is conservative and consists of physical therapy with stretching maneuvers and both passive and active range of motion exercises. The condition usually gradually regresses and completely resolves by seven months of age. During this time, children should be regularly examined at four- to six-week intervals. Follow-up imaging is not required. Approximately 10 to 20% of patients with FC will go on to develop congenital muscular torticollis—a separate entity with potentially more serious consequences. It presents at three to four years of age and is related to the development of a fibrous band of tissue within the SCM. While most cases do not follow clinically evident FC, it is suspected that in some cases FC may have been clinically occult or undiagnosed. Complications of longstanding congenital muscular torticollis involve craniofacial deformity and muscular atrophy, and patients must be treated with surgical release or reimplantation of the muscle to prevent the development of complications.

Fibromatosis colli is a benign, self-limiting condition presenting in the neonate. Treatment is conservative. The diagnosis should be suspected on clinical grounds. Ultrasound is an excellent method for confirming the diagnosis and is important in excluding other neck abnormalities including congenital anomalies and malignant neoplasms.

REFERENCES:

1. Campbell RE, Barone CA, Makris AN, Miller DA, Mohuchy T, Putnam SC 3rd, Schroeder KG, Standiford KN, Stewart DW: Imaging interpretation session: 1993. Fibromatosis colli. Radiographics 1994;14(1):208–9.

2. Chan YL, Cheng CY, Metreweli C: Ultrasonography of congenital muscular torticollis. Pediatr Radiology 1992;22:356–60.

3. Crawford SC, Harnsberger HR, Johnson L, Aoki JR, Giley J: Fibromatosis colli of infancy: CT and sonographic findings. AJR 1998; 151:1183–1184.

4. Maddalozzo J: Head and neck masses in children. The Child's Doctor 1995;12(2):9–17.

5. Maddalozzo J, Goldenberg JD: Pseudotumor of infancy: The role of ultrasonography. ENT-Ear Nose Throat J 1996;April:248–54.

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