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Hemorrhagic thymopharyngeal duct cyst causing airway obstruction in an infant
Hemorrhagic thymopharyngeal duct cyst causing airway obstruction in an infant THOMAS R. LOWRY,
MD,
and TIMOTHY J. O’HARE,
MD, PhD,
Lackland Air Force Base, Texas
N
CASE REPORT A 2-month-old female infant presented to the emergency department with stridor and new onset of a left neck mass. Her past medical history revealed an uncomplicated spontaneous vaginal delivery with recurrent upper respiratory difficulty since birth. The infant was intubated and admitted to the pediatric intensive care unit. Examination revealed a large, fluctuant left neck mass extending from the angle of the mandible to the clavicle with tracheal deviation to the right. Laboratory work-up was unremarkable. Computed tomography (CT) and magnetic resonance imaging (MRI) of the neck revealed a well-circumscribed 3 ⫻ 7-cm cystic mass extending from the angle of the
mandible to the clavicular head and crossing the midline within the retropharyngeal space. Marked tracheal deviation and compression of the carotid sheath were noted. The MRI finding of a fluidfluid level led to the working diagnosis of hemorrhagic lymphatic malformation. On the next day, the neck mass increased in size and the infant was taken to the operating room for direct laryngoscopy and neck exploration. Laryngoscopy revealed tracheal compression and deviation with normal laryngeal anatomy and mucosa. Neck dissection exposed a large cystic mass anterior and medial to the sternocleidomastoid muscle that was consistent with the radiologic findings and closely adherent to the carotid sheath and esophagus. The mass was dissected free with preservation of cranial nerves and great vessels. No direct communication between the mass and mediastinum or aerodigestive tract was noted. The infant was extubated on postoperative day 2 but continued having mild stridor and poor feeding during the week before discharge. Barium esophagraphy failed to reveal tracheoesophageal fistula, but postoperative fiberoptic laryngoscopy noted left vocal cord paresis and a subsequent modified barium swallow study showed aspiration. The infant gradually improved over the ensuing 6 months and currently has normal deglutition without aspiration. Histology of the mass revealed a squamous cell–lined cyst diagnosed on frozen section as a branchial cleft cyst. Further examination revealed Hassall’s corpuscles and the correct diagnosis of cervical thymic cyst.
From the Department of Otolaryngology–Head and Neck Surgery, Wilford Hall Medical Center. Reprint requests: Thomas R. Lowry, MD, 2200 Bergquist Dr, Suite 1, MCSR, Lackland AFB, TX 78236-5300; e-mail, [email protected] or [email protected]. af.mil. Otolaryngol Head Neck Surg 2002;127:467-9 Copyright © 2002 by the American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. 0194-5998/2002/$35.00 ⫹ 0 23/4/129812 doi:10.1067/mhn.2002.129812
DISCUSSION The thymus, which is responsible for proper development of the immune system, develops predominantly from the third pharyngeal pouch. Separation of the right and left primordia from the pharynx and descent into the anterior mediastinum occurs within the sixth gestational week. The path of descent along the paired thymopharyngeal stalks involves migration deep to the thyroid gland and sternocleidomastoid muscle along the carotid
ormal thymus gland development and descent most commonly lead to its anterior mediastinal location directly behind the manubrium of the sternum. However, congenital cervical thymic anomalies, which include thymic and thymopharyngeal duct cysts, may occur as a consequence of an arrest in descent, failure of involution, or as a sequestration of thymic tissue during descent.4 These anomalies, although usually asymptomatic, may present with airway compromise in up to 7% of patients.1 Current literature demonstrates increasing numbers of these potentially life-threatening lesions presenting in children under 2 years of age, with early misdiagnosis being a shared finding. We describe the case of a 2-month-old infant who developed life-threatening airway obstruction secondary to a rapidly enlarging hemorrhagic thymopharyngeal duct cyst.
467
468 LOWRY and O’HARE
Otolaryngology– Head and Neck Surgery November 2002
Fig 1. Axial and coronal MRI demonstrating large hemorrhagic thymopharyngeal duct cyst extending from angle of mandible to upper mediastinum.
Fig 2. Intraoperative photograph showing mass anterior to sternocleidomastoid muscle and carotid sheath.
sheath.3 In normal development, the inferior portions of the thymopharyngeal stalks enlarge, while the proximal portions form epithelial cords that eventually atrophy.3 Thymic tissue may thus be found anywhere along this descent pathway. The thymus grows to a relatively large size by age 2, continues to grow into puberty, and then slowly involutes with increasing age. In 1938, Speer postulated 5 possible origins for cervical thymic cysts5; however, the 2 commonly
accepted theories of development suggest that thymic cysts arise as a result of cystic degeneration of Hassall’s corpuscles or from persistence of the thymopharyngeal duct.1 Recently, Kaufman et al3 astutely defined cervical thymic cysts spanning the neck from the mandibular angle to the clavicle as thymopharyngeal duct cysts. Mikal classified thymic cysts as true cysts, mixed, or false cysts,4 yet the histologic hallmark of all of these lesions is swirls of degenerated keratinizing epithelial cells known as Hassell’s corpuscles. Roughly 100 cases of cervical thymic cysts have been described in the literature, with most occurring in patients between the ages of 2 and 15. Far fewer of these lesions have been described in neonates or infants under the age of 2. Although the majority of cervical thymic cysts are asymptomatic in older patients, these lesions may rapidly enlarge and cause progressive mechanical airway obstruction in neonates or infants due to rapid cyst expansion or hemorrhage.5 This was indeed the case in our patient as evidenced by the finding of a fluid-fluid layer within the cyst on MRI. Additional observations have noted a left-sided and male predominance.
Otolaryngology– Head and Neck Surgery Volume 127 Number 5
Interestingly, nearly all cases of thymic or thymopharyngeal duct cysts in the literature have been misdiagnosed before surgical intervention, with branchial cleft anomalies and lymphatic malformations being cited most commonly. The differential diagnosis includes the more common branchial cleft cyst, thyroglossal duct cyst, lymphatic malformation, cystic teratoma, cystic thymoma, and cystic metastasis, among others.5 Presenting symptoms of dysphagia, dysphonia, stridor, and acute airway obstruction may be evident, especially in very young patients. A key point in narrowing the differential diagnosis during work-up is that thymic cysts usually present in the first decade of life compared with branchial cleft cysts, which present more commonly in the third decade. Also, branchial cleft cysts usually occur relatively higher in the neck. And unlike lymphatic malformations, which demonstrate mediastinal extension in ⬍10% of cases, cervical thymic cysts can present with mediastinal extension in as many as 50% of cases.2 However, because up to 90% of lymphatic malformations occur in children younger than age 2,5 preoperative differentiation from cervical thymic cysts in this age group will continue to be difficult. Additional nonspecific findings in these lesions may include transillumination, transmission of the carotid pulse, and expansion of the cyst with Valsalva.1,3 MRI of the neck is important to characterize the cyst, demonstrate the degree of airway compression, and delineate its soft tissue extension, especially regarding any mediastinal involvement. In
LOWRY and O’HARE
469
our patient, MRI demonstrated a fluid-fluid level within the cyst suggestive of hemorrhage. This correlated clinically with the rapid expansion of the cyst and subsequent airway obstruction. Ultrasound and CT studies may provide additional information, but tissue examination from either fine needle aspiration or excisional biopsy is the only reliable method of diagnosis. Surgical resection of cervical thymic or thymopharyngeal duct cysts has been the mainstay of treatment. With adequate resection, recurrences have not been demonstrated.3 Although ectopic thymic tissue presenting as cervical thymic or thymopharyngeal duct cysts is relatively rare lesions in infants, one must keep them in their differential. Urgent attention should always be given to the infant with new onset or rapid expansion of any neck mass, understanding that airway obstruction may occur. REFERENCES
1. Millman B, Pransky S, Castillo J III, et al. Cervical thymic anomalies. Int J Pediatr Otorhinolaryngol 1999;47:29-39. 2. Billings KR, Rollins NK, Timmons C, et al. Infected neonatal cervical thymic cyst. Otolaryngol Head Neck Surg 2000;123:651-4. 3. Kaufman MR, Smith S, Rothschild MA, et al. Thymopharyngeal duct cyst: an unusual variant of cervical thymic anomalies. Arch Otolaryngol Head Neck Surg 2001;127: 1357-60. 4. Nguyen Q, deTar M, Wells W, et al. Cervical thymic cyst: case reports and review of the literature. Laryngoscope 1996;106(3 Pt 1):247-52. 5. Hendrickson M, Azarow K, Ein S, et al. Congenital thymic cysts in children—mostly misdiagnosed. J Pediatr Surg 1998;33:821-5.
MD,
and TIMOTHY J. O’HARE,
MD, PhD,
Lackland Air Force Base, Texas
N
CASE REPORT A 2-month-old female infant presented to the emergency department with stridor and new onset of a left neck mass. Her past medical history revealed an uncomplicated spontaneous vaginal delivery with recurrent upper respiratory difficulty since birth. The infant was intubated and admitted to the pediatric intensive care unit. Examination revealed a large, fluctuant left neck mass extending from the angle of the mandible to the clavicle with tracheal deviation to the right. Laboratory work-up was unremarkable. Computed tomography (CT) and magnetic resonance imaging (MRI) of the neck revealed a well-circumscribed 3 ⫻ 7-cm cystic mass extending from the angle of the
mandible to the clavicular head and crossing the midline within the retropharyngeal space. Marked tracheal deviation and compression of the carotid sheath were noted. The MRI finding of a fluidfluid level led to the working diagnosis of hemorrhagic lymphatic malformation. On the next day, the neck mass increased in size and the infant was taken to the operating room for direct laryngoscopy and neck exploration. Laryngoscopy revealed tracheal compression and deviation with normal laryngeal anatomy and mucosa. Neck dissection exposed a large cystic mass anterior and medial to the sternocleidomastoid muscle that was consistent with the radiologic findings and closely adherent to the carotid sheath and esophagus. The mass was dissected free with preservation of cranial nerves and great vessels. No direct communication between the mass and mediastinum or aerodigestive tract was noted. The infant was extubated on postoperative day 2 but continued having mild stridor and poor feeding during the week before discharge. Barium esophagraphy failed to reveal tracheoesophageal fistula, but postoperative fiberoptic laryngoscopy noted left vocal cord paresis and a subsequent modified barium swallow study showed aspiration. The infant gradually improved over the ensuing 6 months and currently has normal deglutition without aspiration. Histology of the mass revealed a squamous cell–lined cyst diagnosed on frozen section as a branchial cleft cyst. Further examination revealed Hassall’s corpuscles and the correct diagnosis of cervical thymic cyst.
From the Department of Otolaryngology–Head and Neck Surgery, Wilford Hall Medical Center. Reprint requests: Thomas R. Lowry, MD, 2200 Bergquist Dr, Suite 1, MCSR, Lackland AFB, TX 78236-5300; e-mail, [email protected] or [email protected]. af.mil. Otolaryngol Head Neck Surg 2002;127:467-9 Copyright © 2002 by the American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. 0194-5998/2002/$35.00 ⫹ 0 23/4/129812 doi:10.1067/mhn.2002.129812
DISCUSSION The thymus, which is responsible for proper development of the immune system, develops predominantly from the third pharyngeal pouch. Separation of the right and left primordia from the pharynx and descent into the anterior mediastinum occurs within the sixth gestational week. The path of descent along the paired thymopharyngeal stalks involves migration deep to the thyroid gland and sternocleidomastoid muscle along the carotid
ormal thymus gland development and descent most commonly lead to its anterior mediastinal location directly behind the manubrium of the sternum. However, congenital cervical thymic anomalies, which include thymic and thymopharyngeal duct cysts, may occur as a consequence of an arrest in descent, failure of involution, or as a sequestration of thymic tissue during descent.4 These anomalies, although usually asymptomatic, may present with airway compromise in up to 7% of patients.1 Current literature demonstrates increasing numbers of these potentially life-threatening lesions presenting in children under 2 years of age, with early misdiagnosis being a shared finding. We describe the case of a 2-month-old infant who developed life-threatening airway obstruction secondary to a rapidly enlarging hemorrhagic thymopharyngeal duct cyst.
467
468 LOWRY and O’HARE
Otolaryngology– Head and Neck Surgery November 2002
Fig 1. Axial and coronal MRI demonstrating large hemorrhagic thymopharyngeal duct cyst extending from angle of mandible to upper mediastinum.
Fig 2. Intraoperative photograph showing mass anterior to sternocleidomastoid muscle and carotid sheath.
sheath.3 In normal development, the inferior portions of the thymopharyngeal stalks enlarge, while the proximal portions form epithelial cords that eventually atrophy.3 Thymic tissue may thus be found anywhere along this descent pathway. The thymus grows to a relatively large size by age 2, continues to grow into puberty, and then slowly involutes with increasing age. In 1938, Speer postulated 5 possible origins for cervical thymic cysts5; however, the 2 commonly
accepted theories of development suggest that thymic cysts arise as a result of cystic degeneration of Hassall’s corpuscles or from persistence of the thymopharyngeal duct.1 Recently, Kaufman et al3 astutely defined cervical thymic cysts spanning the neck from the mandibular angle to the clavicle as thymopharyngeal duct cysts. Mikal classified thymic cysts as true cysts, mixed, or false cysts,4 yet the histologic hallmark of all of these lesions is swirls of degenerated keratinizing epithelial cells known as Hassell’s corpuscles. Roughly 100 cases of cervical thymic cysts have been described in the literature, with most occurring in patients between the ages of 2 and 15. Far fewer of these lesions have been described in neonates or infants under the age of 2. Although the majority of cervical thymic cysts are asymptomatic in older patients, these lesions may rapidly enlarge and cause progressive mechanical airway obstruction in neonates or infants due to rapid cyst expansion or hemorrhage.5 This was indeed the case in our patient as evidenced by the finding of a fluid-fluid layer within the cyst on MRI. Additional observations have noted a left-sided and male predominance.
Otolaryngology– Head and Neck Surgery Volume 127 Number 5
Interestingly, nearly all cases of thymic or thymopharyngeal duct cysts in the literature have been misdiagnosed before surgical intervention, with branchial cleft anomalies and lymphatic malformations being cited most commonly. The differential diagnosis includes the more common branchial cleft cyst, thyroglossal duct cyst, lymphatic malformation, cystic teratoma, cystic thymoma, and cystic metastasis, among others.5 Presenting symptoms of dysphagia, dysphonia, stridor, and acute airway obstruction may be evident, especially in very young patients. A key point in narrowing the differential diagnosis during work-up is that thymic cysts usually present in the first decade of life compared with branchial cleft cysts, which present more commonly in the third decade. Also, branchial cleft cysts usually occur relatively higher in the neck. And unlike lymphatic malformations, which demonstrate mediastinal extension in ⬍10% of cases, cervical thymic cysts can present with mediastinal extension in as many as 50% of cases.2 However, because up to 90% of lymphatic malformations occur in children younger than age 2,5 preoperative differentiation from cervical thymic cysts in this age group will continue to be difficult. Additional nonspecific findings in these lesions may include transillumination, transmission of the carotid pulse, and expansion of the cyst with Valsalva.1,3 MRI of the neck is important to characterize the cyst, demonstrate the degree of airway compression, and delineate its soft tissue extension, especially regarding any mediastinal involvement. In
LOWRY and O’HARE
469
our patient, MRI demonstrated a fluid-fluid level within the cyst suggestive of hemorrhage. This correlated clinically with the rapid expansion of the cyst and subsequent airway obstruction. Ultrasound and CT studies may provide additional information, but tissue examination from either fine needle aspiration or excisional biopsy is the only reliable method of diagnosis. Surgical resection of cervical thymic or thymopharyngeal duct cysts has been the mainstay of treatment. With adequate resection, recurrences have not been demonstrated.3 Although ectopic thymic tissue presenting as cervical thymic or thymopharyngeal duct cysts is relatively rare lesions in infants, one must keep them in their differential. Urgent attention should always be given to the infant with new onset or rapid expansion of any neck mass, understanding that airway obstruction may occur. REFERENCES
1. Millman B, Pransky S, Castillo J III, et al. Cervical thymic anomalies. Int J Pediatr Otorhinolaryngol 1999;47:29-39. 2. Billings KR, Rollins NK, Timmons C, et al. Infected neonatal cervical thymic cyst. Otolaryngol Head Neck Surg 2000;123:651-4. 3. Kaufman MR, Smith S, Rothschild MA, et al. Thymopharyngeal duct cyst: an unusual variant of cervical thymic anomalies. Arch Otolaryngol Head Neck Surg 2001;127: 1357-60. 4. Nguyen Q, deTar M, Wells W, et al. Cervical thymic cyst: case reports and review of the literature. Laryngoscope 1996;106(3 Pt 1):247-52. 5. Hendrickson M, Azarow K, Ein S, et al. Congenital thymic cysts in children—mostly misdiagnosed. J Pediatr Surg 1998;33:821-5.