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Recurrent Suppurative Thyroiditis Due to Piriform Sinus Fistula
38
Recurrent Suppurative Thyroiditis Due to Piriform Sinus Fistula Daniel T. Ginat, Juan E. Small
INTRODUCTION Anomalies arising from the third and fourth branchial cleft remnants are quite rare. In particular, branchial abnormalities related to the pharynx are only a small subset of the already rare collection of branchial cleft lesions. Branchial abnormalities with a sinus tract connecting to the pharynx usually present with acute suppurative thyroiditis and a thyroid abscess. The sinus tract connecting to the pharynx serves as a conduit for transmission of hypopharyngeal flora. Most cases of piriform sinus fistulas appear to have an inferiorly coursing branchial sinus with an aperture at the piriform sinus apex. They almost always present with a neck infection, frequently involving the left thyroid lobe. Therefore, anomalies thought to arise from the third and fourth branchial remnants do not seem to conform to the theoretic pathways of third or fourth arch fistulas. The discrepancy between the classical course of either third or fourth branchial anomalies and the observed course of infection related to the piriform sinus apex have led to alternative explanations related to the thymopharyngeal duct. The thymopharyngeal duct forms as the thymus descends during fetal development along a tract that more accurately accounts for the observed infection with thyroid involvement. Therefore, piriform sinus duct abnormalities are most likely secondary to an incompletely obliterated embryologic remnant of the thymopharyngeal duct (of the third branchial pouch). As such, the term “third branchial sinus” is likely most appropriate for branchial lesions with an aperture at the piriform apex and infection involving the thyroid gland (Figs. 38.1 and 38.2).
TEMPORAL EVOLUTION: OVERVIEW The typical presentation is that of recurrent infection and abscess formation in children. Of note, although branchial cleft abnormalities classically and most often present in children, they may also rarely present later in adulthood. The infection is adjacent to or involving the (predominantly left) thyroid gland. The left sided preponderance may be due to the asymmetric development of vascular components of the branchial arches. It is precisely the failure to recognize the underlying duct remnant that results in incomplete management and leads to repeated bouts of infection. Without recognition of the underlying abnormality, the initial sinus tract can be converted to an iatrogenic fistula as a result of nondefinitive incision and drainage procedures. Branchial apparatus anomalies can present as cysts, sinuses, or fistulas. Because they frequently present with infection, when an inflammatory process or abscess is present between the piriform fossa and the thyroid bed in the lower left lower neck, particularly in a young patient, an infected piriform sinus fistula should be suspected (Fig. 38.3). Once the inflammation subsides, a sinus tract can potentially be revealed on imaging. The presence of gas within a recurrent left-sided infected thyroid gland lesion is thought to be characteristic and highly suggestive of this entity in the pediatric population. The associated presence of air along the thymopharyngeal duct sinus tract is considered diagnostic. Imaging with oral contrast can help to delineate the underlying
298
Figure 38.1. Schematic representation of a left-sided third branchial sinus (thymopharyngeal duct remnant). Note the relationship of the sinus tract (orange) to the thyroid gland, as well as the recurrent laryngeal nerve (yellow). (Modified from James A, Stewart C, Warrick P, et al. Branchial sinus of the piriform fossa: reappraisal of third and fourth branchial anomalies. Laryngoscope. 2007;117[11]:1920–1924.)
sinus tract, particularly once the acute inflammation has subsided. Suggesting the presence of an underlying branchial apparatus anomaly and performing the appropriate imaging to delineate the extent of the anomaly is important for surgical management because complete resection is crucial for minimizing the risk of recurrence. Pharyngoscopy reveals a sinus tract aperture at the apex of the piriform fossa. Definitive surgical management includes dissection of the sinus tract, as well as hemithyroidectomy. Because the recurrent laryngeal nerve is generally intimately associated with the sinus tract, care must be taken to preserve this structure.
MIMICS AND DIFFERENTIAL DIAGNOSIS A potential mimic of suppurative thyroiditis associated with piriform sinus fistula is an infected or inflamed thyroglossal duct cyst. The thyroglossal duct cysts are often situated just to the left of the midline along the strap muscles, but midline extension superior to the hyoid bone and into the tongue base region can be a helpful clue (Fig. 38.4). Otherwise, the main differential diagnosis for
CHAPTER 38 Recurrent Suppurative Thyroiditis Due to Piriform Sinus Fistula
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38
A
B
D
E
G
H
C
F
Figure 38.2. Third branchial sinus and suppurative thyroiditis in a young adult male presenting with left-sided neck pain and odynophagia. Coronal (A), sagittal (B), and axial (C–H) contrast-enhanced computed tomography images of the neck demonstrate a left-sided thyroid abscess (orange arrows). Infectious inflammatory changes extend from the left piriform sinus (red arrows) inferiorly to the level of the thyroid abscess.
300
PART I Infection
5 years later
Initial presentation
A
B
Figure 38.3. Temporal evolution of recurrent suppurative thyroiditis. The axial postcontrast computed tomography (CT) at initial presentation (A) shows a low attenuation abscess in the left lobe of the thyroid (arrow) with stranding of the adjacent fat. The axial postcontrast CT when the patient returned with recurrent symptoms 5 years later (B) shows a recurrent abscess in the left lobe of the thyroid (arrow), with an almost identical appearance as on the initial CT.
A
B
C
Figure 38.4. Inflamed thyroglossal duct cyst. Axial T1 (A), fat-suppressed postcontrast T1 (B), and coronal fat-suppressed T2 (C) magnetic resonance images show a peripherally enhancing cystic lesion (arrows) in the left visceral space at the level of the thyroid, with extension into the tongue base (arrowhead, C).
acute suppurative thyroiditis associated with a piriform sinus fistula is an infection that is not associated with an underlying anomaly. However, acute suppurative thyroiditis is uncommon and due mainly to the unusual ability of the thyroid to withstand bacterial infection. In the lower neck, infections more commonly occur in the visceral space due to penetration of foreign bodies
(Fig. 38.5) and in the posterior triangle of the neck, secondary to suppurative lymphadenitis (Fig. 38.6). Otherwise, an important entity to consider in a patient with a persistent anterior neck lesion is neoplasm. With papillary thyroid carcinoma for example, the presence of calcifications associated is suggestive of this diagnosis (Fig. 38.7).
CHAPTER 38 Recurrent Suppurative Thyroiditis Due to Piriform Sinus Fistula
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38
A
C
B
E
F
D
G
Figure 38.5. Foreign body rupture of piriform sinus. Eighty-year-old female with a 5-day history of throat pain and discomfort starting after eating a chicken bone, now presenting with worsening sore throat, pain, fever, or leukocytosis. (A–G) Coronal, axial, and sagittal computed tomography scans show a retained chicken bone fragment (red arrows) extending inferior to the left piriform sinus with resultant air containing neck abscess involving the superior left thyroid lobe (green arrows).
Figure 38.6. Pyogenic cervical lymphadenitis. Coronal postcontrast computed tomography obtained in a child with fever and left neck swelling shows enlarged left posterior triangle lymph nodes with central hypoattenuation.
Figure 38.7. Papillary thyroid carcinoma. Axial postcontrast computed tomography shows an infiltrative mixed cystic and solid mass with calcifications arising from the left lobe of the thyroid gland.
SUGGESTED READINGS
Bar-Ziv J, Slasky BS, Sichel JY, et al. Branchial pouch sinus tract from the piriform fossa causing acute suppurative thyroiditis, neck abscess, or both: CT appearance and the use of air as a contrast agent. AJR Am J Roentgenol. 1996;167(6):1569–1572. James A, Stewart C, Warrick P, et al. Branchial sinus of the piriform fossa: reappraisal of third and fourth branchial anomalies. Laryngoscope. 2007;117(11):1920–1924. Kruijff S, Sywak MS, Sidhu SB, et al. Thyroidal abscesses in third and fourth branchial anomalies: not only a paediatric diagnosis. ANZ J Surg. 2015;85(7–8):578–581. doi:10.1111/ans.12576. [Epub 2014 Mar 27].
Park SW, Han MH, Sung MH, et al. Neck infection associated with pyriform sinus fistula: imaging findings. AJNR Am J Neuroradiol. 2000;21(5):817–822. Thomas B, Shroff M, Forte V, et al. Revisiting imaging features and the embryologic basis of third and fourth branchial anomalies. AJNR Am J Neuroradiol. 2010;31(4):755–760. doi:10.3174/ajnr.A1902. [Epub 2009 Dec 10]. Tovi F, Gatot A, Bar-Ziv J, et al. Recurrent suppurative thyroiditis due to fourth branchial pouch sinus. Int J Pediatr Otorhinolaryngol. 1985;9(1):89–96.
Recurrent Suppurative Thyroiditis Due to Piriform Sinus Fistula Daniel T. Ginat, Juan E. Small
INTRODUCTION Anomalies arising from the third and fourth branchial cleft remnants are quite rare. In particular, branchial abnormalities related to the pharynx are only a small subset of the already rare collection of branchial cleft lesions. Branchial abnormalities with a sinus tract connecting to the pharynx usually present with acute suppurative thyroiditis and a thyroid abscess. The sinus tract connecting to the pharynx serves as a conduit for transmission of hypopharyngeal flora. Most cases of piriform sinus fistulas appear to have an inferiorly coursing branchial sinus with an aperture at the piriform sinus apex. They almost always present with a neck infection, frequently involving the left thyroid lobe. Therefore, anomalies thought to arise from the third and fourth branchial remnants do not seem to conform to the theoretic pathways of third or fourth arch fistulas. The discrepancy between the classical course of either third or fourth branchial anomalies and the observed course of infection related to the piriform sinus apex have led to alternative explanations related to the thymopharyngeal duct. The thymopharyngeal duct forms as the thymus descends during fetal development along a tract that more accurately accounts for the observed infection with thyroid involvement. Therefore, piriform sinus duct abnormalities are most likely secondary to an incompletely obliterated embryologic remnant of the thymopharyngeal duct (of the third branchial pouch). As such, the term “third branchial sinus” is likely most appropriate for branchial lesions with an aperture at the piriform apex and infection involving the thyroid gland (Figs. 38.1 and 38.2).
TEMPORAL EVOLUTION: OVERVIEW The typical presentation is that of recurrent infection and abscess formation in children. Of note, although branchial cleft abnormalities classically and most often present in children, they may also rarely present later in adulthood. The infection is adjacent to or involving the (predominantly left) thyroid gland. The left sided preponderance may be due to the asymmetric development of vascular components of the branchial arches. It is precisely the failure to recognize the underlying duct remnant that results in incomplete management and leads to repeated bouts of infection. Without recognition of the underlying abnormality, the initial sinus tract can be converted to an iatrogenic fistula as a result of nondefinitive incision and drainage procedures. Branchial apparatus anomalies can present as cysts, sinuses, or fistulas. Because they frequently present with infection, when an inflammatory process or abscess is present between the piriform fossa and the thyroid bed in the lower left lower neck, particularly in a young patient, an infected piriform sinus fistula should be suspected (Fig. 38.3). Once the inflammation subsides, a sinus tract can potentially be revealed on imaging. The presence of gas within a recurrent left-sided infected thyroid gland lesion is thought to be characteristic and highly suggestive of this entity in the pediatric population. The associated presence of air along the thymopharyngeal duct sinus tract is considered diagnostic. Imaging with oral contrast can help to delineate the underlying
298
Figure 38.1. Schematic representation of a left-sided third branchial sinus (thymopharyngeal duct remnant). Note the relationship of the sinus tract (orange) to the thyroid gland, as well as the recurrent laryngeal nerve (yellow). (Modified from James A, Stewart C, Warrick P, et al. Branchial sinus of the piriform fossa: reappraisal of third and fourth branchial anomalies. Laryngoscope. 2007;117[11]:1920–1924.)
sinus tract, particularly once the acute inflammation has subsided. Suggesting the presence of an underlying branchial apparatus anomaly and performing the appropriate imaging to delineate the extent of the anomaly is important for surgical management because complete resection is crucial for minimizing the risk of recurrence. Pharyngoscopy reveals a sinus tract aperture at the apex of the piriform fossa. Definitive surgical management includes dissection of the sinus tract, as well as hemithyroidectomy. Because the recurrent laryngeal nerve is generally intimately associated with the sinus tract, care must be taken to preserve this structure.
MIMICS AND DIFFERENTIAL DIAGNOSIS A potential mimic of suppurative thyroiditis associated with piriform sinus fistula is an infected or inflamed thyroglossal duct cyst. The thyroglossal duct cysts are often situated just to the left of the midline along the strap muscles, but midline extension superior to the hyoid bone and into the tongue base region can be a helpful clue (Fig. 38.4). Otherwise, the main differential diagnosis for
CHAPTER 38 Recurrent Suppurative Thyroiditis Due to Piriform Sinus Fistula
299
38
A
B
D
E
G
H
C
F
Figure 38.2. Third branchial sinus and suppurative thyroiditis in a young adult male presenting with left-sided neck pain and odynophagia. Coronal (A), sagittal (B), and axial (C–H) contrast-enhanced computed tomography images of the neck demonstrate a left-sided thyroid abscess (orange arrows). Infectious inflammatory changes extend from the left piriform sinus (red arrows) inferiorly to the level of the thyroid abscess.
300
PART I Infection
5 years later
Initial presentation
A
B
Figure 38.3. Temporal evolution of recurrent suppurative thyroiditis. The axial postcontrast computed tomography (CT) at initial presentation (A) shows a low attenuation abscess in the left lobe of the thyroid (arrow) with stranding of the adjacent fat. The axial postcontrast CT when the patient returned with recurrent symptoms 5 years later (B) shows a recurrent abscess in the left lobe of the thyroid (arrow), with an almost identical appearance as on the initial CT.
A
B
C
Figure 38.4. Inflamed thyroglossal duct cyst. Axial T1 (A), fat-suppressed postcontrast T1 (B), and coronal fat-suppressed T2 (C) magnetic resonance images show a peripherally enhancing cystic lesion (arrows) in the left visceral space at the level of the thyroid, with extension into the tongue base (arrowhead, C).
acute suppurative thyroiditis associated with a piriform sinus fistula is an infection that is not associated with an underlying anomaly. However, acute suppurative thyroiditis is uncommon and due mainly to the unusual ability of the thyroid to withstand bacterial infection. In the lower neck, infections more commonly occur in the visceral space due to penetration of foreign bodies
(Fig. 38.5) and in the posterior triangle of the neck, secondary to suppurative lymphadenitis (Fig. 38.6). Otherwise, an important entity to consider in a patient with a persistent anterior neck lesion is neoplasm. With papillary thyroid carcinoma for example, the presence of calcifications associated is suggestive of this diagnosis (Fig. 38.7).
CHAPTER 38 Recurrent Suppurative Thyroiditis Due to Piriform Sinus Fistula
301
38
A
C
B
E
F
D
G
Figure 38.5. Foreign body rupture of piriform sinus. Eighty-year-old female with a 5-day history of throat pain and discomfort starting after eating a chicken bone, now presenting with worsening sore throat, pain, fever, or leukocytosis. (A–G) Coronal, axial, and sagittal computed tomography scans show a retained chicken bone fragment (red arrows) extending inferior to the left piriform sinus with resultant air containing neck abscess involving the superior left thyroid lobe (green arrows).
Figure 38.6. Pyogenic cervical lymphadenitis. Coronal postcontrast computed tomography obtained in a child with fever and left neck swelling shows enlarged left posterior triangle lymph nodes with central hypoattenuation.
Figure 38.7. Papillary thyroid carcinoma. Axial postcontrast computed tomography shows an infiltrative mixed cystic and solid mass with calcifications arising from the left lobe of the thyroid gland.
SUGGESTED READINGS
Bar-Ziv J, Slasky BS, Sichel JY, et al. Branchial pouch sinus tract from the piriform fossa causing acute suppurative thyroiditis, neck abscess, or both: CT appearance and the use of air as a contrast agent. AJR Am J Roentgenol. 1996;167(6):1569–1572. James A, Stewart C, Warrick P, et al. Branchial sinus of the piriform fossa: reappraisal of third and fourth branchial anomalies. Laryngoscope. 2007;117(11):1920–1924. Kruijff S, Sywak MS, Sidhu SB, et al. Thyroidal abscesses in third and fourth branchial anomalies: not only a paediatric diagnosis. ANZ J Surg. 2015;85(7–8):578–581. doi:10.1111/ans.12576. [Epub 2014 Mar 27].
Park SW, Han MH, Sung MH, et al. Neck infection associated with pyriform sinus fistula: imaging findings. AJNR Am J Neuroradiol. 2000;21(5):817–822. Thomas B, Shroff M, Forte V, et al. Revisiting imaging features and the embryologic basis of third and fourth branchial anomalies. AJNR Am J Neuroradiol. 2010;31(4):755–760. doi:10.3174/ajnr.A1902. [Epub 2009 Dec 10]. Tovi F, Gatot A, Bar-Ziv J, et al. Recurrent suppurative thyroiditis due to fourth branchial pouch sinus. Int J Pediatr Otorhinolaryngol. 1985;9(1):89–96.