Indian J Pediatr DOI 10.1007/s12098-014-1505-5

PICTURE OF THE MONTH

Undescended Thymus: A Rare Cause of Midline Neck Swelling Poonam Sherwani & Shivani Pahwa & Shweta Singhal & Mahender Kaur Narula

Received: 28 March 2014 / Accepted: 5 June 2014 # Dr. K C Chaudhuri Foundation 2014

A 4-y-old child was brought to the Surgical OPD with complaint of a mass in the neck since birth which was more visible when the child cried and moved while swallowing. Physical examination revealed fullness in the suprasternal notch, and a distinct midline mass was visible in the neck when the child cried or swallowed (Fig. 1a). Ultrasound of the neck revealed cervical extension of normal thymic tissue in the neck below the level of thyroid showing normal homogenous hypoechoic echotexture with speckled appearance. Low dose CECT neck

and upper chest was done to see the mediastinal extension which revealed normal thymic tissue in the neck with minimal extension into superior mediastinum (Fig. 1b and c). Thymus is a lymphoid organ in infants and children and plays an important role in cell mediated immunity [1]. Major portion of the primordial thymus appears in the sixth week of fetal life from the ventral aspect of third pharyngeal pouch and the rudimentary portion from fourth pharyngeal pouch. Undescended thymus is a rare cause of midline neck swelling in a

Fig. 1 a Clinical photograph of the child showing midline neck swelling (arrow) during swallowing b Grey scale ultrasound of the neck (transverse view) below the level of thyroid showing thymus with its typical speckled appearance (arrow) anterior to neck vessels c CECT chest (including lower neck) coronal reconstruction image depicting the extension of thymus from the neck to mediastinum (arrow)

P. Sherwani (*) : S. Pahwa : S. Singhal : M. K. Narula Department of Radiodiagnosis, Lady Hardinge Medical College and Associated Hospitals, New Delhi, India e-mail: [email protected]

child. Other major differentials include brancial cleft cyst, cystic hygroma, thyroglossal duct cyst, cystic teratoma, thyroid or parathyroid lesions, lymphadenopathy and vascular

Indian J Pediatr

lesions. Imaging includes conventional radiography, ultrasonography, computed tomography, MRI and nuclear scan (Gallium 61). Final diagnosis requires histopathological examination which can obviate the need for invasive procedures of thymectomy which can result in immune dysfunction. Undescended thymus should be kept in the differentials of midline neck swelling in children despite its rarity, and imaging confirms the diagnosis and reduces the inadvertent surgeries and invasive procedures.

Conflict of Interest None. Source of Funding None.

Reference 1. Tunkel DE, Erozan YS, Weir EG. Ectopic cervical thymic tissue: diagnosis by fine needle aspiration. Arch Pathol Lab Med. 2001;125: 278–81.

Undescended thymus: a rare cause of midline neck swelling.

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