Most Frequently Missed
Diagnosis: Retropharyngeal
Suppurative Lymphadenitis
J Shah, MD; L Lanier, MD; C L Sistrom, MD; D Rajderkar, MD;
A Ghaffari, MD; A Mancuso, MD;I M Schmalfuss, MD
University of Florida, Department of Radiology
Contact: [email protected]
The authors have no financial disclosure in regard to this educational
exhibit.
Background:
Computer aided online simulation (SIM) of
emergency imaging studies was developed
Designed to test residents for readiness for call
Providing proficient & objective assessment of
resident competence in the emergency/critical
care imaging & affirmation of milestone
achievements
8 hour simulation of 65 emergent & critical care
cases of varying degrees of difficulty, including
normal studies
Presentation via full DICOM image sets
Dictation of free responses into text boxes labelled:
o Critical findings
o Incidental findings
o Acuity ranking
Background:
SIM was taken by 103 first (R1) & second (R2) year residents from 9 USA radiology training programs in 2014
Suppurative retropharyngeal space (RPS) lymphadenitis was presented
o 100% of residents failed to make the correct diagnosis
o Incorrect answers included:• RPS abscess (48%)
• Peritonsillar abscess (24%)
• Tonsillar abscess (15%)
• Abscess without localization (1%)
Results:
SIM was taken by 103 first (R1) & second (R2) year residents from 9 USA radiology training programs in 2014
Suppurative retropharyngeal space (RPS) lymphadenitis was presented
o 100% of residents failed to make the correct diagnosis
Results:
Conclusion: Significant cognitive gap exists in
differentiating suppurative RPS lymphadenitis from
abscess placing patients at risk for unnecessary surgical
procedure
Teaching Points:
Familiarize the radiologist with clinical and imaging
findings of RPS suppurative lymphadenitis
Discuss clinical and imaging features of mimics of RPS
suppurative lymphadenitis to improve diagnostic
competency
Outline:
SIM case presentation
Discussion of normal RPS anatomy
Presentation of clinical & imaging findings of RPS suppurative lymphadenitis and potential complications
Review of mimics of RPS suppurative lymphadenitis
SIM Case: 9 month old male with fever &
decreased neck movement
Axial contrast enhanced CT (CECT) shows mild narrowing of the upper airway (*) caused by a focal, rim enhancing hypodensity in
the right RPS with marked surrounding edema. The lateral nature of the disease is not consistent with a RPS abscess but rather with
suppurated RPS lymphadenitis.
*
RPS Anatomy
Boundaries:o Anterior: Middle layer of deep cervical fascia
o Posterior: Deep layer of deep cervical fascia
o Lateral: Alar fascia (arises from deep cervical fascia)
o Superior: Skull base
o Inferior: Fusion of middle & deep cervical fascia from
T2 to T6
Contents:o Loose connective tissue
o Lateral and medial RPS lymph nodes
RPS Imaging Anatomy: Axial plane - CT
Axial CECT shows thin layer of fat in the RPS between the pharyngeal constrictor & longus colli muscles. RPS lymph nodes are divided into lateral & medial groups (2) with the lateral being located medial to the
internal carotid artery (ICA) while the medial ones are in midline.
RPS Imaging Anatomy: Axial plane - MRI
Axial T1+Gd image reveals a normal lateral RPS lymph node located immediately
medial to the ICA and lateral to the longus colli muscle. Axial T2 image in an
infant shows a normal medial RPS lymph node located in the midline between the
longus colli muscles and a normal left lateral RPS lymph node medial to the ICA.
RPS Imaging Anatomy: Sagittal plane
Danger space is a potential space while RPS is an actual space. In a normal patient, the two cannot be distinguished with a small fat plane seen
in the RPS on T1 image.
RPS Imaging Anatomy: Sagittal plane
Sagittal CT in bone algorithm in a different patient shows air tracking
inferiorly into the mediastinum posterior to the esophagus consistent with
the danger space as the RPS stops at the thoracic inlet level.
RPS Suppurative Lymphadenitis
Demographics:
o Most common in children between ages of 2 to 6 yearso Teens and young adults occasionally affected
o No gender predilection
Presentation:
o Young children - high fevers, feeding problems and airway compromise
o Older children - fevers, sore throat, odynophagia, and neck pain
Pathophysiology:
o Staphylococcus or Streptococcus head & neck infection -> RPS reactive lymphadenopathy -> RPS suppurativelymphadenitis -> RPS abscess
RPS Diagnostic Confusion
In RPS space:o RPS suppurative lymphadenitis
o RPS abscess
o RPS edema
o Necrotic RPS nodal metastasis
In adjacent anatomical structures:o Tonsillar abscess
o Peritonsillar abscess
o Longus colli calcific tendinitis
o Soft tissue tumors / cysts
Increasing Diagnostic Accuracy
Characteristic RPS Suppurative
LymphadenitisRPS Abscess RPS Edema
Fluid Distribution Unilateral Fills the RPS from
side to side
Fills the RPS from
side to side
Configuration
and mass effect
Rounded or ovoid,
mass effect
depends on size
Rounded or ovoid;
mass effect
depends on size
“Bow-Tie”
configuration on
axial images,
sagittal images
demonstrates
tapered margins.
Mild to no mass
effect
Enhancing Wall Sometimes Always No
• Necrotic metastatic RPS lymph nodes mimic RPS suppurative
lymphadenitis but affect elderly patients.
RPS Suppurative Lymphadenitis
Axial CECT images in a 8 year old boy with dysphagia, fever & neck pain reveals a hypodense, rim enhancing lesion in the right RPS as the lesion is medial to ICA & posterior to the pharyngeal constrictor muscle. Notice the reactive lymphadenopathy in level II with subtle
edema in the RPS. The unilateral nature of the lesion is consistent with RPS suppurative lymphadenitis with clear fluid & negative cultures on
aspiration, confirming the diagnosis and ruling out RPS abscess.
RPS Abscess
CECT reveals an irregular, rim enhancing hypodensity in the RPS. The small air pockets & bilateral nature of the disease indicates RPS abscess rather than suppurated RPS lymph node. This requires search for underlying etiology, e.g. discitis/osteomyelitis as seen on sagittal
T1+Gd image in this patient.
RPS Abscess
CECT reveals a rim enhancing hypodensity in the RPS bilaterally
consistent with RPS abscess which was related to recent anterior
fusion surgery. The diagnosis of RPS abscess requires CT imaging to
the carina to exclude thoracic involvement as seen in this patient.
Notice also the small abscess in the sternocleidomastoid muscle.
RPS Edema
CECT of a 60 year old male following anterior fusion surgery reveals
hypodensity in the RPS bilaterally. The lack of enhancement is
consistent with RPS edema rather than RPS abscess as seen in the
patient on the prior slide. The RPS edema spontaneously resolved with
the lateral cervical spine plain film performed 2 months later showing
normal thickness of the prevertebral stripe.
RPS Edema
Non-contrasted CT in a 65 year old shows hypodensity in the RPS bilaterally. The lack of mass effect, the tapered margins and additional subcutaneous stranding are consistent with RPS edema rather than
RPS abscess. Search for venous thrombosis / obstruction is required in every patient with unexplained RPS edema. Superior vena cava
syndrome due to mediastinal adenopathy was confirmed in this patient.
RPS Edema
Bilateral RPS edema in two different patients related to venous thrombophlebitis with involvement of the internal jugular vein only in
the patient on the left and extension into smaller neck veins in the patient on the right. Notice that the degree of the edema does not
indicate the extent of thrombophlebitis.
Necrotic RPS Nodal Metastasis
CECT in a 58 year old male reveals a focal rim enhancing hypodensity in the right RPS. The age of the patient & the associated large
abnormal group IIB nodal conglomerate without adjacent inflammatory changes are consistent with metastatic disease rather than suppurative RPS adenitis. Fullness & fat plane obscuration was seen in the right
nasopharynx and confirmed as cancer on subsequent biopsy.
Necrotic RPS Nodal Metastasis
CECT in a 49 year old male reveals a right, oval hypodensity with rim
enhancement & inflammatory thickening of the adjacent soft tissues
mimicking suppurative RPS adenitis. However, in an adult patient this is a
necrotic RPS metastasis until proven otherwise and requires search for
an underlying malignancy in particular of the oropharynx & thyroid gland
as in this patient.
RPS Pathology - Management
Varies based on pathology
ManagementRPS Suppurative
LymphadenitisRPS Abscess RPS Edema
Treatment
Intravenous
antibiotics; most
patients improve in
24 to 48 hours
Surgical drainage
Non-surgical &
depending on
cause of edema
Additional
Recommen-
dations
Airway protection;
Incision & drainage if
progression to RPS
abscess or if the
lymph node exceeds
3 cm in short axis
Airway protection;
Chest CT to exclude
extension into
mediastinum; Search
for underlying cause
e.g. discitis /
osteomyelitis
Airway protection;
Search for
underlying cause
e.g. venous
thrombosis /
thrombophlebitis
RPS Pathology – Reporting Guidelines
Is the process centered in the RPS lymph node or truly in the RPS?
If in RPS lymph node, is it inflammatory indicating suppurativeadenitis or neoplastic?
If truly in the RPS, is it infectious indicating RPS abscess or just edema?
Associated findings / complications, such as: o Airway compromise?o Venous obstruction or thrombophlebitis? o Osteomyelitis/discitis?o Epidural abscess with spinal canal or cord compromise?o Oropharyngeal or thyroid gland malignancy?
Extent of disease & relationship to carotid artery / jugular vein Are additional studies or intervention such as aspiration/biopsy
needed to establish the correct diagnosis?
Additional RPS Lymphadenitis Mimics:
Tonsillar abscess
Peritonsillar abscess
Longus colli calcific tendinitis
Soft tissue tumors / cysts
Tonsillar versus Peritonsillar Abscess
CECT in two different patients reveals focal fluid collections in the right tonsillar region. The differentiating feature between these two entities is the location of the tonsils. In the patient with tonsillar abscess, the fluid
collection is centered in the tonsil while the tonsil is normal but medially displaced in peritonsillar abscess. Both collections are markedly
anterior to the RPS.
Longus Colli Calcific Tendinitis
Clinical presentation mimics RPS infection:o Fevers, dysphagia, odynophagia & neck pain
o May have elevated inflammatory markers including ESR & WBC
Imaging findings on CT/MRI include:o Edema within the longus colli musculature & RPSo Calcification of the longus colli tendons = differentiating
feature; may be subtle
Treatment with NSAIDS
Longus Colli Calcific Tendinitis
54 year old male with dysphagia & fevers is referred to the hospital for
suspected discitis/osteomyelitis. CT scout image reveals marked
prevertebral soft tissue thickening that is caused by widened and
hypodense RPS without associated enhancement on the CECT
consistent with RPS edema. Notice the small calcifications at C2
leading to the correct diagnosis of calcific longus colli tendinitis.
Soft Tissue Tumors / Cysts
Axial T1 and T2 images in a 26 year female demonstrates a well-defined
T1 hypointense & T2 hyperintense mass medial to the ICA that
compresses the longus colli muscle. This could be mistaken for a
suppurative RPS adenitis. The marked enhancement on the T1+Gd
image is however not consistent with such a diagnosis. Pathology
revealed a schwanomma likely arising from the sympathetic chain as the
patient did not have vocal cord paralysis to indicate vagus nerve origin.
Soft Tissue Tumors / Cysts
T2 images in a 60 year old female reveal a well-defined, oval,
hyperintense lesion that might be mistaken for suppurative RPS
adenitis. Patient’s age, lack of inflammatory changes, location anterior to
the ICA and the heterogeneous internal enhancement on the T1+Gd
image contradict such a diagnosis. The location is characteristic of a
parapharyngeal space mass with the pathology revealing benign minor
salivary gland tumor.
Soft Tissue Tumors / Cysts
CECT in a 57 year old male shows a well-defined, oval, hypodense
lesion medial to ICA concerning for suppurative RPS adenitis. Patient’s
age & the lack of enhancement are contradicting such a diagnosis. Axial
T1 images reveal that the lesion is spontaneously hyperintense due to
proteinaceous fluid & located anterior to the pharyngeal constrictor
muscle consistent with a nasopharyngeal retention cyst.
Conclusion:
Identification of key clinical and imaging findings of
suppurative RPS lymphadenitis requires attention in
resident education
This exhibit focuses on improving competence in
diagnosing suppurative RPS lymphadenitis through
o Presentation of imaging features of common pathologies of the
RPS that are confused with suppurative RPS adenitis (e.g. RPS
abscess, RPS edema, & necrotic RPS nodal metastasis)
o Review of other mimics of RPS pathologies that affect adjacent
anatomical structures (e.g. nasopharynx, tonsillar &
paravertebral structures)
References
• Mancuso AA, Hanafee WN. Head and Neck Radiology. Head and Neck Radiology. Volumes I and II. Lippincott & Williams and Wilkins, 2011.
• Shefelbine SE, Mancuso AA, Gajewski B, Stringer S, Sedwick JD. Pediatric retropharyngeal lymphadenitis: differentiation from retropharyngeal abscess and treatment implications. Otolaryngol Head Neck Surg. 2007;136(2):182-8.
• Hoang JK, Branstetter BF, Eastwood JD, et al. Multiplanar CT and MRI of Collections in the Retropharyngeal Space: Is It an Abscess? AJR. 2011;196: W426-W432.
• Hoang JK, Vanka J, Ludwig BJ, et al. Evaluation of Cervical Lymph Nodes in Head and Neck Cancer With CT and MRI: Tips, Traps, and a Systematic Approach. AJR. 2013;200: W17-W25
• widionline.com