Pseudotumor of infancy presents as a discrete, firm mass in the distal sternocleidomastoid muscle in infants two to four weeks of age. Congenital muscular torticollis may develop from the resultant fibrosis in 10 to 20 percent of cases. Hip dysplasia is an associated feature of congenital muscular torticollis in approximately 10 percent of cases. Pseudotumor of infancy must be differentiated from other causes of cervical soft tissue masses. Diagnostic choices include fine-needle aspiration biopsy, cervical radiography, ultrasonography, computed tomographic scanning of the head and neck, and magnetic resonance imaging. Left untreated, congenital muscular torticollis may lead to significant craniofacial asymmetry and scoliosis. Heat, massage and passive stretching exercises are the preferred initial treatments for pseudotumor and torticollis. More than 70 percent of patients will respond to this approach. Surgery should be reserved for treatment of cases that persist past the first year of life.
Pseudotumor of infancy is also known as sternocleidomastoid tumor of infancy or fibromatosis colli. It typically presents as a painless, firm, fibrous mass in the substance of the sternocleidomastoid muscle in infants two to four weeks of age (Figure 1). Pseudotumor most commonly occurs in the sternal head and the distal third of the muscle. Pseudotumor of infancy occurs in approximately 0.4 percent of all newborns. The mass usually increases in size until one month of age, remains static for two to three months, then gradually diminishes in size and disappears clinically.[1-3] However, the resulting fibrosis of the sternocleidomastoid muscle may lead to congenital muscular torticollis in 10 to 20 percent of cases.[4-5]
In one study of infants with pseudotumor, the sternocleidomastoid muscle was clinically normal in 50 percent by six months of age. Thirty percent of infants had some degree of palpable muscle fibrosis that was not severe enough to cause torticollis by one year of age, and torticollis developed in the remaining 20 percent of infants.
Not all patients with congenital muscular torticollis have a history of pseudotumor, although it is believed that these cases represent unrecognized muscular fibrosis. It is hypothesized that pseudotumor and torticollis are part of a spectrum of the same disease process (sternocleidomastoid fibrosis), but with different manifestations. Thus, congenital torticollis is a sign of another process and not a disease itself.
Congenital muscular torticollis is the third most common congenital musculoskeletal anomaly, following dislocation of the hip and clubfoot.[1,6] Although the term "congenital" is used here, the condition is more correctly referred to as "infantile" or "childhood" torticollis, since it is not present at birth. Congenital muscular torticollis generally presents before one year of age but may manifest later, when the original insult affects subsequent growth of the sternocleidomastoid muscle. In a study of 232 infants and children with torticollis, two distinct age groups at the time of presentation were found: patients less than one year of age (with an average age of four months), and those over one year of age (with an average age of six years and four months). Incidence according to gender, race and left- versus right-sided involvement are approximately equal.[1,7]
Coexisting congenital hip dysplasia is a significant finding in infants with congenital muscular torticollis.[6,7] In the study of 232 infants and children with torticollis, 32 of 232 patients had some form of hip dysplasia, ranging from subluxation to frank dislocation. Hip dysplasia more commonly involved the side with sternocleidomastoid fibrosis.
The persistent contracture of the muscle pulls the infant's head laterally (head tilt) to the ipsilateral side and rotates the chin and face to the contralateral side (Figure 2). If left untreated, torticollis may lead to significant craniofacial asymmetry or scoliosis. Facial asymmetry may be noted as early as two to three months of age and usually appears with flattening of the contralateral occipitoparietal region and the ipsilateral fronto-orbital region. This condition appears as inferior positioning of the orbit, ear and angle of the mouth.
As with many poorly understood diseases, more than one theory has been proposed for the etiology of pseudotumor of infancy and congenital muscular torticollis. The more common putative causes are fetal malposition, birth trauma, vascular compromise and heredity.[10-13] The etiology may be different in different infants.
Pseudotumor of infancy and congenital muscular torticollis must be considered separately. However, in both conditions, the clinician must identify underlying and associated disorders.
The differential diagnosis of pseudotumor of infancy alone is basically a differentiation of congenital or neonatal lateral neck masses. It is helpful to categorize neck masses into inflammatory, traumatic, congenital and neoplastic causes (Table 1). Pseudotumor is listed under the traumatic category rather than the congenital category.
STUART B. PORTER, D.O. is a staff family physician at Weed Army Hospital, Ft. Irwin, Calif. He graduated from the Kirksville (Mo. College of Osteopathic Medicine and completed a residency in family medicine at Madigan Army Medical Center, Tacoma, Wash.
B. WAYNE BLOUNT, M.D., M.P.H. is an associate professor in the Department of Family and Preventive Medicine at Emory University School of Medicine, Atlanta. He received a medical degree from the University of Miami School of Medicine. He completed a residency in family medicine at DeWitt Army Hospital, Fort Belvoir, Va., and a faculty development fellowship at Madigan Army Medical Center.
Address correspondence to B. Wayne Blount, M.D., M.P.H., Department of Family and Preventive Medicine, Emory University School of Medicine, 60 Butler St., S.E., Atlanta, GA 30303-3219.
COPYRIGHT 1995 American Academy of Family Physicians
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