Abstract
Benign extra-gonadal germ cell tumors, known as teratoma or dermoid cysts, are commonly found in the anterior mediastinum in association with the thymic gland. This association is due to their common site of embryological origins, from the third and the fourth pharyngeal pouches. Since it is not unusual to find normal thymic tissue in the neck, germ cell tumors arising from here will present as a cervical tumor. We submit the typical images of one such tumor in a young adult. Intraoperatively, the tumor was well encapsulated and was connected to the mediastinal thymus by a long pedicle of thymic tissue. It was not related to the thyroid gland unlike a primary cervical teratoma. We present these typical images of a mediastinal dermoid in this unusual cervical location. The differential diagnoses to be considered clinically are primary cervical teratomas, thyroid tumors, lymph nodal pathologies, and branchial cyst.
Keywords: Teratoma, Thymus, Neck, Tumor, Computerized tomography
Benign extra-gonadal germ cell tumors, also known as teratoma or dermoid cysts, are frequently found in the anterior mediastinum [1]. Here, they are found in association with the thymic gland.
Embryologically, it is postulated that these tumors arise from cells close to the third and fourth pharyngeal pouches from where the thymus also develops and hence this close association [2]. During the descent of the thymic gland from here into the mediastinum prenatally, thymic glandular tissues may get left behind in the neck. Besides these, the gland, especially its superior horns, may remain in the neck [3]. Thus, a germ cell tumor arising from the thymic tissue in the neck will present as a cervical tumor.
This is in contrast to the primary cervical teratomas, which are suspected to arise from the thyroid anlage [4]. These are usually found in children and are often malignant. Primary cervical teratomas are also rare, constituting less than 5% of the teratomas in the children [5].
We present a rare case of a dermoid cyst arising from the thymic tissue in the neck. An 18-year-old girl presented with a progressively growing asymptomatic swelling in the mid and lower neck for the last 5 months (Fig. 1). Clinical examination showed a 6-cm diameter, well defined, firm swelling in the lower neck, deep to the strap muscles, not moving with deglutition. Serum markers to identify malignant germ cell tumors were normal.
Fig. 1.
Clinical photograph of the tumor in the mid and lower neck anteriorly
Computerized tomogram of the chest showed a well-defined, lobulated tumor with predominant fat density, having smaller foci of soft tissue densities and calcifications, in the left paratracheal region of the lower neck, minimally extending to the upper thorax (Fig. 2a, b, c).
Fig. 2.
Computerized tomogram images of the neck and upper chest. Coronal (a), Sagittal (b), and Axial (c) views showing a large cervical tumor of fat density, with some solid areas and calcifications
The tumor was excised through a left upper partial median sternotomy. Intraoperatively, the tumor was well encapsulated and was connected to the left lobe of the thymus by a long pedicle of thymic tissue (Fig. 3). The tumor was not related to the thyroid gland. It contained putty material and tufts of hair suggestive of a dermoid cyst. This was confirmed by histopathology.
Fig. 3.
Specimen photograph of the excised dermoid cyst attached to the left superior horn and lobe of the thymus
We present this set of typical images of a teratoma for its unusual location. Clinically, the differential diagnoses for a similar swelling are primary cervical teratoma, thyroid tumors, lymph nodal pathologies, bronchial cyst, and lymphangiomas.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Footnotes
Key message
Benign teratoma, commonly found in the anterior mediastinum, may occasionally present in the neck, due to its developmental association with the thymic tissue which may be found in the neck. We present the images of such a cervical teratoma. The differential diagnoses to be considered are primary cervical dermoids, thyroid and lymph nodal pathologies, and branchial cysts.
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References
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