Portuguese Version

Year:  1974  Vol. 40   Ed. 2 - (18º)

Artigos Originais

Pages: 186 to 187

Persistent Cervical Parathyroid-Thymus Complex Causing Recurrent Respiratory Obstruction and Mediastinal Emphysema

Author(s): Hemendra N. Bhatnagar, M. D. *

Case Report

A two-year-old white girl was seen on 4-7-71 on consultation because of severe respiratory problem. The patient's mother gave a history that a big bunch suddenly appeared in the front of the neck. On examination at this time a soft mass was seen protruding in lower midline, just above the sternum. This mass was seen only when she cried or extended the head posteriorly. This was not visible when the patient was quiet or lying on her back. At times the mass gave the appearance of a slightly bifurcating, prominent vein or vessel and presumptive diagnosis of either an extension of thymus or thyro-glossal, remnant was made. Chest xray and lateral xray of the neck failed to show any evident pathology and thyroid scan was not satisfactory. On 4-12-71 exploration of the neck was performed. At this time a whitish cystic vessel or duct was seen almost in midline. This was bluish in the central portion. On aspiration of the cystic area, clear watery fluid was obtained. This vessel-like structure extended inferiorly behind the sternum and almost faded superiorly into deeper tissue. A small segment of this structure was excised for biopsy. Histopathology showed a cross-section of tubular structure made of fibrous connective tissue and lined by an ill-defined epithelium or endothelium. Epithelial cells were rather cylindrical and in one section there were some cells resembling lymphocytes and this was reported as either consistent with thyro-glossal duct or a dilated lymph vessel.

This girl was subsequently discharged Nome. However, she continued to have recurrent episodes of respiratory problem for which she was hospitalized a few times. She was again seen on consultation on 2-4-72 being admitted to the hospital the previous day because of severe respiratory problem. She had marked dyspnoea with marked retraction in the suprasternal region. She was taken to the operating room and a tracheostomy was done through the previous incisional scat. At this time a markedly bulging, pale-white edematous tract or structure was seen on the left lateral aspect of the trachea extending from the thyroid cartilage, down inferiorly behind the sternum. The mass moved with respirations pressing significantly on the left lateral aspect of the trachea. A small segment from the structure was excised. Histopathology report on this was consistent with parathyroid gland. A direct laryngoscopy at this time showed a "W" shaped epiglottis which was quite soft and sort of curled over. A few hours later she was found to have marked difficulty in breathing through the tracheostomy tube. She was still retracting in the thoraco-abdominal region, more so on expiration. The neck was explored at this time and a fairly large pinkish polpoid mass was found encroaching on the tracheostomy. This was partially excised. Histopathology report on frozen section as well as permanent sections was consistent with thymus gland. Chest xrays at this time showed mediastinal emphysema both anteriorly and posteriorly. A chest film which was taken prior to tracheostomy was reviewed at this time and showed posterior mediastinal emphysema which was missed at first. This mediastinal emphysema continued to improve over a period of a few days and she was finally discharged sixteen days later.

Discussion

In reviewing the embryology the parathyroid glands are formed from the entoderm of the. III visceral pouches in close proximity to the developing thymus gland. The thymus gland descends to the pericardium dragging the parathytoid anlage with it. According to McGregor this is sometimes called Parathyroid III. This may descend with the thymus and be situated anywhere in its course, like anterior mediastinum, or thymus gland itself, or in its capsule or gland proper. Parathyroid glands or tumors have also been found in other locations such as carotid sheath, in the thyroid gland, in the tracheoesophageal groove, and in the anterior-posterior mediastinum between the trachea and the esophagus or even behind the esophagus. In retrospect the first histopatologic diagnosis of a dilated lymph vessel or remnant of thyroglossal duct in 1971 would be consistent with extension from thymus gland and an earlier stage of "thyro-thytnus ligament" or even a lymphatic vessel from the thymus either directly emptying into a vein or extending superiorly in deeper tissue to drain into lymphatics of the thyroid or neck. The second hospitalization operative findings were consistent with embryological malformation and/or persistence of a left parathyroid-thymus complex, arrested at an earlier developmental stage, exerting external pressure on the trachea. This pressure on the soft trachea caused respiratory obstruction especially in certain positions of the head and the coughing and gasping spells evidently caused posterior mediastinal emphysema, secondary to rupture of a bleb. The case was managed during the second hospitalization with partial thymetcomy and tracheostomy.

References

1. Moseley, 1. E. and Som, Max: Cervical Thymus Gland. Journal of Mt. Sinai Hospital, Vol. 21: 5, 1955.
2. McGregor, A. Lee: Synopsis of Anatomy (Williams and Wilkins Co. - Baltimore) 9th Edition.

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* Chairman, Department of Otolaryngology - E. A. Seton Hospital Waterville, Maine. U. S. A.

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