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Clinical Problem Solving: Radiology
March 2005

Radiology Quiz Case 2—Diagnosis

Author Affiliations


Arch Otolaryngol Head Neck Surg. 2005;131(3):277-278. doi:10.1001/archotol.131.3.277

The mass, which was found between the posterior belly of the digastric muscle and the hypoglossal nerve, was excised, and a fibrous tract between the skin lesion and the neck mass was maintained. Microscopic examination of the excised mass demonstrated the presence of thymic tissue. Histologically, no fistuous tract was noted, and the skin lesion showed only an area of fibrosis.

The finding of a thymic remnant (ectopic thymic tissue) in the neck of a pediatric patient is an uncommon yet well-known occurrence. Fewer than 100 cases have been reported in the literature since 1901,1 and fewer than 12 reports have been described in infants, as in the present case. More than 90% of the cases involving ectopic thymic tissue either are cystic or contain cystic components, and fewer than 10% of the cases reported are completely solid, as in the present case. The correlation between the subtypes of thymic remnants is unknown, although some authors attribute the cystic components to degenerative changes in the thymic tissue, which are caused by outgrowing its blood supply.2

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