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161
Radiologic Evaluation Normal and Diseased Cervical
of the Posterior
Space
L.,
Geoffrey D. Parker1 H. Ric Harnsberger
,
The posterior cervical space seen on cross-sectional imaging of the neck constitutes most of the posterior triangle seen on clinical examination. Although triangular anatomy relates best to the surface perspective of the clinician, a spatial approach to anatomy works better for the radiologist viewing axial images. The posterior cervical space is defined as the area in the posterolateral portion of the neck from the skull base to the clavicles deep to the sternomastoid and trapezius muscles but superficial to the
prevertebral
space.
Its principal
contents
are fat, the spinal
accessory
nerve, and lymph
nodes. We analyzed CT and MR images and clinical records of 63 patients known or suspected to have disease of the posterior cervical space to determine the imaging features that mark a lesion as originating in the posterior cervical space and the spectrum of diseases that arise there. Of the 63 patients in the study, four had clinical pseudomasses, nine had congenital lesions, 10 had inflammatory disease, six had benign tumors, and 34 had malignant tumors. A typical mass lesion of the posterior cervical space was centered within the fat of the space, between the deep and superficial layers of
the
deep
cervical
fascia.
Characteristic
displacements
caused
by
a mass
in the
posterior cervical space included anterornedial displacement of the carotid space and posteromedial displacement of the prevertebral space. Our study shows that the differential diagnosis of lesions of the posterior cervical space reflects the normal contents of the space, and that diagnosis can thereby be predicted from knowledge of the normal anatomy and contents of the space. AJR
157:161-165,
July
1991
Presented at the annual meeting of the American Society of Head & Neck Radiology, New Orleans, LA, May 1990. 1 Both authors: Department of Radiology, Uni-
The posterior cervical space (PCS) constitutes a major portion of the posterior triangle of the neck, a term that has long been used by anatomists and clinicians when referring to the posterior and lateral aspects of the neck [1 ]. The posterior triangle continues to be a useful term for describing the location of a mass in the posterolateral aspect of the neck between the posterior margin of the sternomastoid muscle and the anterior margin of the trapezius muscle during palpation. However, as it is primarily a two-dimensional, longitudinal concept, it is difficult to apply accurately during interpretation of cross-sectional images (CT or MA), particularly in the axial plane. The term posterior cervical space was originally introduced when neck infections in the posterior triangle of the neck were described (Fig. 1 ) [2]. Recent authors have applied this term to the space seen on CT and MR posteromedial to the sternomastoid muscle from the skull base to the clavicles [3, 4]. We performed a retrospective review of patients with lesions in the PCS in order to identify the specific features on CT or MR images that indicate that a lesion has originated in the PCS. The study was also undertaken to identify the spectrum of diseases occurring in the PCS.
versity of Utah School of Medicine, 50 N. Medical Dr., Salt Lake City, UT 84132. Address reprint requests to H. A. Hamsberger.
Materials
0361-803x/91/1 571-0161 © American Roentgen Aay Society
PCS who
Received November 21 revision January 15, 1991.
,
1990;
accepted
after
Clinical
and Methods and
radiologic
underwent
records
imaging
of 63 patients
between
with
known
or suspected
1 981 and 1 990 were
analyzed.
abnormalities
These
records
in the
were
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162
PARKER
AND
A
HARNSBERGER
AJR:157,
July
1991
B
Fig. 1.-A, Axial drawing through infrahyoid neck at level of thyroid gland shows posterior cervical space (black area) and bordering spaces. Superficial space (asterisks). B, Lateral drawing of posterior cervical space shows normal contents of space and structures of its floor. Spinal accessory lymph node chain angles anteromedlally toward apex of deep cervical nodal chain (arrow), ending at jugulodigastric node (asterisk) beneath sternomastoid muscle. V = vein, m = muscle, n = nerve, a = artery.
reviewed
to
determine
the
age
and
sex
of
the
patients
and
the
diagnoses, which were established pathologically in all cases except when CT findings (e.g., typical density in a lipoma) were diagnostic. of the 63 study patients, 40 were male and 23 were female, ranging from 6 months to 77 years. All imaging studies were reviewed by two radiologists to identify characteristic imaging features of a mass in the
PCS.
of the
63
patients,
60
underwent
CT scanning;
in 54 of the 60,
IV contrast enhancement was used. CT scanning was performed on a Siemens Somatom 2 (Siemens, Iselin, NJ) or a GE 9800 (General Electric Medical Systems, Milwaukee, WI) scanner. bolus-drip
Contiguous
4- or 5-mm
MR imaging
was
axial images
performed
with
were a
obtained
in all cases.
GE Signa scanner
in eight
patients. Axial short and long TR images were obtained in all patients. Five of these patients also underwent CT scanning. Three patients had MR imaging enhanced with gadopentetate dimeglumine; all three had unenhanced short TR MR sequences also. Fig. 2.-Axial cervical space.
Results Review of the mass lesions in the study group revealed a typical appearance of a mass lesion of the PCS (Fig. 2). Features that were thought to identify a mass as primary to the PCS included a lesion centered within the fat of the PCS or, if larger than the PCS, displacing the carotid space anteromedially and the prevertebral space posteromedially. When the mass was smaller and within the infrahyoid portion of the PCS, a fat plane was usually present between the mass and the carotid space. Four patients had pseudomasses, defined as a mass lesion suspected clinically with no tumor revealed on radiologic examination (Fig. 3). Nine patients had congenital lesions, of which four were in the cystic hygroma/lymphangioma spectrum (Fig. 4A) and four were PCS branchial cleft cysts (Fig. 4B). One patient had a PCS hemangioma. Ten patients had inflammatory disease related to the spinal accessory lymph node chain. Three of these patients had simple reactive lymphadenopathy (Fig. 5A), and an additional three
patients
the inflammatory
had
suppurative
process
adenopathy.
had extended
In four
through
patients
the capsule
drawing shows typical appearance of mass in posterior Carotid space is displaced anteromedially (open arrow), sternomastoid muscle is displaced anterolaterally (arrowheads), and musculature of prevertebral space is displaced posteromedially (solid arrows).
of the involved lymph node to form a true PCS abscess (Fig. 5B). Six patients had benign neoplasms. The most common of these, lipoma (Fig. 6A), was present in three patients. Thirtyfour patients had malignant neoplasia. Primary malignant neoplasms of the PCS were rare. Single examples of a liposarcoma (Fig. 6B) and a synovial sarcoma were seen. Thirty-two patients had malignant lymphadenopathy; metastatic squamous cell carcinoma was seen in i 6 of these (Fig. 7). Nine patients had non-Hodgkin lymphoma (Fig. 8A). Three patients had metastatic papillary carcinoma of the thyroid (Fig. 9) and two patients had Hodgkin lymphoma (Fig. 8B).
Discussion The PCS is a three-dimensional space largely corresponding to the posterior triangle of the neck. As spatial terminology permits more accurate description of the position of a mass
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AJA:157,
NORMAL
July 1991
AND
Fig. 3.-Pseudomass in posterior cervical space (PCS). Axial enhanced CT scan shows a hypertrophied right levator scapulae muscle (L) with atrophy of right trapezius muscle (t) and absence of right sternomastoid muscle owing to previous radical neck dissection for undifferencarcinoma. Hypertrophied muscle PCS pseudomass, which led to clinical concern for recurrent PCS tumor. ClinIcally unsuspected nodal recurrent tumor is seen also in contralateral carotid space (T). tiated
parotid
produced
a clinical
Fig. 5.-Inflammatory lymphadenopathy and complications. A, Axial enhanced CT scan shows reactive lymphadenopathy (n) in posterior cervical space (PCS). Concern over possibility of low-grade lymphoma led to surgical biopsy. No infectious cause was Identified. B, Abscess in PCS. Axial enhanced CT scan in a 6-month-old boy with fever and a mass on left side of neck. Poorly defined fluid collection (A) in pCS with surrounding enhancement is due to spread of inflammatory process beyond capsule of node. Multiple small reactive nodes (n) are also present in PCS adjacent to abscess.
Fig. 6.-Neoplasms cal space (PCS). A, Axial
enhanced
in primary CT scan
posterior
shows
a lipoma
with its center in PCS. Lipoma extends into superficial space B, Axial enhanced
coma (M) in PCS.
cervi(L)
laterally
(55).
CT scan shows a liposar-
DISEASED
Fig. 4.-Congenital
POSTERIOR
lesions
CERVICAL
in posterior
cervical
SPACE
163
space (PCS).
A, Cystic hygroma. Axial enhanced CT scan in a 6-month-old boy shows a multilobulated PCS mass with fluid-density contents and smooth enhancing margins typical of a cystic hygroma. In this case,
density of fluid in cysts (c) is increased owing to superimposed infection. B, Branchial cleft cyst. Axial enhanced CT scan shows a right-sided unilocular fluid-density mass (B) in PCS. Most second branchial cleft cysts are found anteromedial to carotid space. Location of this cyst suggests a third branchial cleft cyst.
164
PARKER
AND
HARNSBERGER
AJR:157,
July 1991
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Fig. 7.-Malignant squamous cell carcinoma lymphadenopathy. A, Intranodal metastases. Axial enhanced CT scan shows multiple ring-enhancing lymph nodes (I) in posterior cervical space (PCS) with necrotic
centers due to metastatic deposits from laryngeal squamous cell carcinoma. B, Extranodal metastatic spread. Axial enhanced
CT scan shows
a large
necrotic
extranodal
metastatic deposit in PCS (m) and early extension through prevertebral fascia into paraspinal of prevertebral space (arrows). Recognition
portion of this
spread beyond PCS mandates more extensive resection than was clinically planned and underscores importance of fascial boundaries and spatial localization in assessment of extent of disease.
Fig. 8.-Lymphoma. A, Non-Hodgkin lymphoma. Axial CT scan shows large deposits of extranodal non-Hodgkin lymphoma (L) in left posterior cervical space. No central necrosis is evident; involvement of internal jugular nodal chain within carotid space is present (N). B, Hodgkin lymphoma. Axial enhanced CT scan shows early spinal accessory nodal Hodgkin
lymphoma (I). More anterior internal jugular nodal disease (d) is present also.
Fig. 9.-Hemorrhagic metastatic nodal papillary carcinoma of thyroid. Oblique sagittal Ti-weighted MR image, 857/30 (TR/TE), shows a mixed-intensity mass (m) of the posterior cervical space with areas of isointensity and hyperintensity consistent with
methemoglobin.
When
ciated with a nodal deposit thyroid
on cross-sectional imaging studies than does two-dimensional triangle terminology, the term PCS is a more useful concept to the imager than the term posterior triangle. Because a PCS lesion has a limited differential diagnosis, localization of a mass to this space allows construction of a more focused or limited differential diagnosis than would be possible with triangle localization. Spatial localization of a lesion also permits more accurate surgical treatment of inflammatory disease [2] and malignant tumors (Fig. 7B). The PCS is found in the posterolateral aspect of the neck (Fig. 1A), extending from the skull base to the clavicle (Fig. 1 B). The space is bounded on its deep margin by the deep layer of deep cervical fascia, which separates the PCS from
origins
should
hemorrhage
is asso-
in infrahyoid
neck,
be suspected.
the anterior prevertebral space proper and the more posterior paraspinal prevertebral space (Fig. 1 A). Superficially, the PCS is bounded by the superficial layer of deep cervical fascia, which splits to enclose the sternomastoid and trapezius musdes [4]. Anteromedially, the PCS is separated from the carotid space by the carotid sheath. Seen from the side, the PCS has the appearance of a posteriorly tilted triangle (Fig. 1 B). The main contents of the PCS are the spinal accessory lymph node chain, the spinal accessory nerve, and fat [5, 6]. As the contents of the PCS are limited, the differential diagnosis of diseases affecting the PCS is also limited. The principal abnormality occurring in this space arises from involvement of the spinal accessory lymph node chain. Notable
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AJR:157,
July 1991
NORMAL
AND
DISEASED
exceptions to this pattern of PCS nodal involvement include lesions arising from the fat of the PCS (lipoma and liposarcoma) and congenital lesions (cystic hygroma and branchial cleft cysts) [7]. The most common disease of the PCS is metastatic squamous cell carcinoma. Spinal accessory chain lymphadenopathy within the PCS is a classic manifestation of an occult nasopharyngeal mucosal space malignancy [8, 9]. Nevertheless, in our series lymphadenopathy in the PCS occurred more often as a result of lesions elsewhere in the pharyngeal mucosal space and the larynx, owing to their greater overall frequency. Lymphoma, both Hodgkin and non-Hodgkin types, was represented frequently in our series. The disease typically occurred intranodally within the PCS, although extranodal, extralymphatic deposits were seen also [1 0]. Lymphomatous deposits typically showed no evidence of necrosis unless previously treated or of high grade. Metastatic lymphadenopathy tended to be seen in other lymph node chains in the adjacent neck in the majority of cases, especially in patients with both non-Hodgkin and Hodgkin lymphoma and metastatic squamous cell carcinoma. In one patient with metastatic adenocarcinoma of the lung, PCS lymphadenopathy was confined to the immediate supraclavicular region. In such patients with predominantly low PCS lymphadenopathy, the primary tumor should be sought in the thyroid, thorax, or abdomen [4, 9]. Inflammatory lymphadenopathy also is common in the PCS. Inflammatory processes begin with enlargement of a lymph node and may progress if virulent or untreated to suppuration within the lymph node. If the process continues to go untreated, spread through the capsule of the lymph node is seen, forming an abscess in the PCS. Suppurative lymphadenopathy tends to occur with unusual pathogens. Those identified in our study were tularemia, atypical mycobacteria, and cat scratch fever. Congenital lesions are seen not infrequently in the PCS. Most commonly these are multiseptated lesions in the cystic hygroma/lymphangioma spectrum [1 1 12]. The branchial cleft cysts seen in this study were atypical in that they were centered in the PCS, not the submandibular space where the second branchial cleft cysts are found [7]. Although difficult ,
to prove,
it is tempting
to speculate
that these
PCS branchial
POSTERIOR
CERVICAL
SPACE
165
cleft cysts are actually third branchial cleft cysts. Benign tumors of the PCS are rare. Lipoma is seen most often. Neurofibromas and hemangiomas also can be found in this space. These lesions also are derived from the tissues normally found in the PCS. Three kinds of pseudomasses were identified in the PCS. The term pseudomass is used when there is a clinically palpable lesion of the posterior triangle and CT or MR identifies it as a nonsurgical abnormality outside of the PCS. Cervical ribs and prominent cervical transverse processes are the common bony pseudomasses. Another clinical pseudomass is found in levator scapulae hypertrophy commonly seen after radical neck dissection with sacrifice of the spinal accessory nerve. The hypertrophied levator scapulae muscle can cause concern for tumor recurrence in the posterior triangle of the neck [4].
REFERENCES 1 . Last AJ. Anatomy: Livingstone,
regional 1978:363-366
and
applied,
2. Nyberg DA, Jeffrey RB, Brant-Zawadzki
6th
ed.
New
York:
Churchill-
M, Federle M, Dillon W. Computed
tomography of cervical infections. J Comput Assist Tomogr 1985;9: 288-296 3. Davis WL, Harnsberger HA, SmokerWRK, Watanabe AS. Retropharyngeal
space: evaluation
of normal anatomy
and diseases
with CT and MR
Radiology 1990;174:59-64 4. Hamsberger HA. Handbooks in radiology: head and neck imaging. Chicago: Year Book Medical, 1990:138-187 5. Basmajian JV, ed. Grant’s method ofanatomy, 10th ed. Baltimore: Williams & Wilkins, 1980:426-432 6. Aouviere M. Lymphatic system of the head and neck. In: Tobias MJ, trans. Anatomy of the human lymphatic system. Ann Arbor, Ml: Edwards Brothers, 1938;24-25 7. Hamsberger HR, Mancuso AA, Muraki AS, et al. Branchial cleft anomalies and their mimics: computed tomographic evaluation. Radiology i984;1 52:739-748 8. Becker W, Nauman HH, Platz CR. Neck (Including the thyroid). In: Buckingham AA, ed. Ear, nose and throat diseases. New York: Thieme, imaging.
1989:472-523 9. Som PM. Lymph nodes of the neck. Radiology 10. Hamsberger HA, Bragg DG, Osbom the head and neck: CT evaluation
1987;165:593-600
AG, et al. Non-Hodgkin lymphoma of of nodal and extranodal sites. AJR
1987:149:785-791 1 1 . Silverman PM, Korobkin M, Moore the neck. J Comput Assist Tomogr
AV. CT diagnosis
of cystic
hygroma
of
1983;7:519-520 12. Karmody CS, Fortson JK, Calcaterra VE. Lymphangiomas of the head and neck in adults. Otolaryngol Head Neck Surg 1982:90:283-288
161
Radiologic Evaluation Normal and Diseased Cervical
of the Posterior
Space
L.,
Geoffrey D. Parker1 H. Ric Harnsberger
,
The posterior cervical space seen on cross-sectional imaging of the neck constitutes most of the posterior triangle seen on clinical examination. Although triangular anatomy relates best to the surface perspective of the clinician, a spatial approach to anatomy works better for the radiologist viewing axial images. The posterior cervical space is defined as the area in the posterolateral portion of the neck from the skull base to the clavicles deep to the sternomastoid and trapezius muscles but superficial to the
prevertebral
space.
Its principal
contents
are fat, the spinal
accessory
nerve, and lymph
nodes. We analyzed CT and MR images and clinical records of 63 patients known or suspected to have disease of the posterior cervical space to determine the imaging features that mark a lesion as originating in the posterior cervical space and the spectrum of diseases that arise there. Of the 63 patients in the study, four had clinical pseudomasses, nine had congenital lesions, 10 had inflammatory disease, six had benign tumors, and 34 had malignant tumors. A typical mass lesion of the posterior cervical space was centered within the fat of the space, between the deep and superficial layers of
the
deep
cervical
fascia.
Characteristic
displacements
caused
by
a mass
in the
posterior cervical space included anterornedial displacement of the carotid space and posteromedial displacement of the prevertebral space. Our study shows that the differential diagnosis of lesions of the posterior cervical space reflects the normal contents of the space, and that diagnosis can thereby be predicted from knowledge of the normal anatomy and contents of the space. AJR
157:161-165,
July
1991
Presented at the annual meeting of the American Society of Head & Neck Radiology, New Orleans, LA, May 1990. 1 Both authors: Department of Radiology, Uni-
The posterior cervical space (PCS) constitutes a major portion of the posterior triangle of the neck, a term that has long been used by anatomists and clinicians when referring to the posterior and lateral aspects of the neck [1 ]. The posterior triangle continues to be a useful term for describing the location of a mass in the posterolateral aspect of the neck between the posterior margin of the sternomastoid muscle and the anterior margin of the trapezius muscle during palpation. However, as it is primarily a two-dimensional, longitudinal concept, it is difficult to apply accurately during interpretation of cross-sectional images (CT or MA), particularly in the axial plane. The term posterior cervical space was originally introduced when neck infections in the posterior triangle of the neck were described (Fig. 1 ) [2]. Recent authors have applied this term to the space seen on CT and MR posteromedial to the sternomastoid muscle from the skull base to the clavicles [3, 4]. We performed a retrospective review of patients with lesions in the PCS in order to identify the specific features on CT or MR images that indicate that a lesion has originated in the PCS. The study was also undertaken to identify the spectrum of diseases occurring in the PCS.
versity of Utah School of Medicine, 50 N. Medical Dr., Salt Lake City, UT 84132. Address reprint requests to H. A. Hamsberger.
Materials
0361-803x/91/1 571-0161 © American Roentgen Aay Society
PCS who
Received November 21 revision January 15, 1991.
,
1990;
accepted
after
Clinical
and Methods and
radiologic
underwent
records
imaging
of 63 patients
between
with
known
or suspected
1 981 and 1 990 were
analyzed.
abnormalities
These
records
in the
were
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162
PARKER
AND
A
HARNSBERGER
AJR:157,
July
1991
B
Fig. 1.-A, Axial drawing through infrahyoid neck at level of thyroid gland shows posterior cervical space (black area) and bordering spaces. Superficial space (asterisks). B, Lateral drawing of posterior cervical space shows normal contents of space and structures of its floor. Spinal accessory lymph node chain angles anteromedlally toward apex of deep cervical nodal chain (arrow), ending at jugulodigastric node (asterisk) beneath sternomastoid muscle. V = vein, m = muscle, n = nerve, a = artery.
reviewed
to
determine
the
age
and
sex
of
the
patients
and
the
diagnoses, which were established pathologically in all cases except when CT findings (e.g., typical density in a lipoma) were diagnostic. of the 63 study patients, 40 were male and 23 were female, ranging from 6 months to 77 years. All imaging studies were reviewed by two radiologists to identify characteristic imaging features of a mass in the
PCS.
of the
63
patients,
60
underwent
CT scanning;
in 54 of the 60,
IV contrast enhancement was used. CT scanning was performed on a Siemens Somatom 2 (Siemens, Iselin, NJ) or a GE 9800 (General Electric Medical Systems, Milwaukee, WI) scanner. bolus-drip
Contiguous
4- or 5-mm
MR imaging
was
axial images
performed
with
were a
obtained
in all cases.
GE Signa scanner
in eight
patients. Axial short and long TR images were obtained in all patients. Five of these patients also underwent CT scanning. Three patients had MR imaging enhanced with gadopentetate dimeglumine; all three had unenhanced short TR MR sequences also. Fig. 2.-Axial cervical space.
Results Review of the mass lesions in the study group revealed a typical appearance of a mass lesion of the PCS (Fig. 2). Features that were thought to identify a mass as primary to the PCS included a lesion centered within the fat of the PCS or, if larger than the PCS, displacing the carotid space anteromedially and the prevertebral space posteromedially. When the mass was smaller and within the infrahyoid portion of the PCS, a fat plane was usually present between the mass and the carotid space. Four patients had pseudomasses, defined as a mass lesion suspected clinically with no tumor revealed on radiologic examination (Fig. 3). Nine patients had congenital lesions, of which four were in the cystic hygroma/lymphangioma spectrum (Fig. 4A) and four were PCS branchial cleft cysts (Fig. 4B). One patient had a PCS hemangioma. Ten patients had inflammatory disease related to the spinal accessory lymph node chain. Three of these patients had simple reactive lymphadenopathy (Fig. 5A), and an additional three
patients
the inflammatory
had
suppurative
process
adenopathy.
had extended
In four
through
patients
the capsule
drawing shows typical appearance of mass in posterior Carotid space is displaced anteromedially (open arrow), sternomastoid muscle is displaced anterolaterally (arrowheads), and musculature of prevertebral space is displaced posteromedially (solid arrows).
of the involved lymph node to form a true PCS abscess (Fig. 5B). Six patients had benign neoplasms. The most common of these, lipoma (Fig. 6A), was present in three patients. Thirtyfour patients had malignant neoplasia. Primary malignant neoplasms of the PCS were rare. Single examples of a liposarcoma (Fig. 6B) and a synovial sarcoma were seen. Thirty-two patients had malignant lymphadenopathy; metastatic squamous cell carcinoma was seen in i 6 of these (Fig. 7). Nine patients had non-Hodgkin lymphoma (Fig. 8A). Three patients had metastatic papillary carcinoma of the thyroid (Fig. 9) and two patients had Hodgkin lymphoma (Fig. 8B).
Discussion The PCS is a three-dimensional space largely corresponding to the posterior triangle of the neck. As spatial terminology permits more accurate description of the position of a mass
Downloaded from www.ajronline.org by 178.77.154.16 on 11/14/15 from IP address 178.77.154.16. Copyright ARRS. For personal use only; all rights reserved
AJA:157,
NORMAL
July 1991
AND
Fig. 3.-Pseudomass in posterior cervical space (PCS). Axial enhanced CT scan shows a hypertrophied right levator scapulae muscle (L) with atrophy of right trapezius muscle (t) and absence of right sternomastoid muscle owing to previous radical neck dissection for undifferencarcinoma. Hypertrophied muscle PCS pseudomass, which led to clinical concern for recurrent PCS tumor. ClinIcally unsuspected nodal recurrent tumor is seen also in contralateral carotid space (T). tiated
parotid
produced
a clinical
Fig. 5.-Inflammatory lymphadenopathy and complications. A, Axial enhanced CT scan shows reactive lymphadenopathy (n) in posterior cervical space (PCS). Concern over possibility of low-grade lymphoma led to surgical biopsy. No infectious cause was Identified. B, Abscess in PCS. Axial enhanced CT scan in a 6-month-old boy with fever and a mass on left side of neck. Poorly defined fluid collection (A) in pCS with surrounding enhancement is due to spread of inflammatory process beyond capsule of node. Multiple small reactive nodes (n) are also present in PCS adjacent to abscess.
Fig. 6.-Neoplasms cal space (PCS). A, Axial
enhanced
in primary CT scan
posterior
shows
a lipoma
with its center in PCS. Lipoma extends into superficial space B, Axial enhanced
coma (M) in PCS.
cervi(L)
laterally
(55).
CT scan shows a liposar-
DISEASED
Fig. 4.-Congenital
POSTERIOR
lesions
CERVICAL
in posterior
cervical
SPACE
163
space (PCS).
A, Cystic hygroma. Axial enhanced CT scan in a 6-month-old boy shows a multilobulated PCS mass with fluid-density contents and smooth enhancing margins typical of a cystic hygroma. In this case,
density of fluid in cysts (c) is increased owing to superimposed infection. B, Branchial cleft cyst. Axial enhanced CT scan shows a right-sided unilocular fluid-density mass (B) in PCS. Most second branchial cleft cysts are found anteromedial to carotid space. Location of this cyst suggests a third branchial cleft cyst.
164
PARKER
AND
HARNSBERGER
AJR:157,
July 1991
Downloaded from www.ajronline.org by 178.77.154.16 on 11/14/15 from IP address 178.77.154.16. Copyright ARRS. For personal use only; all rights reserved
Fig. 7.-Malignant squamous cell carcinoma lymphadenopathy. A, Intranodal metastases. Axial enhanced CT scan shows multiple ring-enhancing lymph nodes (I) in posterior cervical space (PCS) with necrotic
centers due to metastatic deposits from laryngeal squamous cell carcinoma. B, Extranodal metastatic spread. Axial enhanced
CT scan shows
a large
necrotic
extranodal
metastatic deposit in PCS (m) and early extension through prevertebral fascia into paraspinal of prevertebral space (arrows). Recognition
portion of this
spread beyond PCS mandates more extensive resection than was clinically planned and underscores importance of fascial boundaries and spatial localization in assessment of extent of disease.
Fig. 8.-Lymphoma. A, Non-Hodgkin lymphoma. Axial CT scan shows large deposits of extranodal non-Hodgkin lymphoma (L) in left posterior cervical space. No central necrosis is evident; involvement of internal jugular nodal chain within carotid space is present (N). B, Hodgkin lymphoma. Axial enhanced CT scan shows early spinal accessory nodal Hodgkin
lymphoma (I). More anterior internal jugular nodal disease (d) is present also.
Fig. 9.-Hemorrhagic metastatic nodal papillary carcinoma of thyroid. Oblique sagittal Ti-weighted MR image, 857/30 (TR/TE), shows a mixed-intensity mass (m) of the posterior cervical space with areas of isointensity and hyperintensity consistent with
methemoglobin.
When
ciated with a nodal deposit thyroid
on cross-sectional imaging studies than does two-dimensional triangle terminology, the term PCS is a more useful concept to the imager than the term posterior triangle. Because a PCS lesion has a limited differential diagnosis, localization of a mass to this space allows construction of a more focused or limited differential diagnosis than would be possible with triangle localization. Spatial localization of a lesion also permits more accurate surgical treatment of inflammatory disease [2] and malignant tumors (Fig. 7B). The PCS is found in the posterolateral aspect of the neck (Fig. 1A), extending from the skull base to the clavicle (Fig. 1 B). The space is bounded on its deep margin by the deep layer of deep cervical fascia, which separates the PCS from
origins
should
hemorrhage
is asso-
in infrahyoid
neck,
be suspected.
the anterior prevertebral space proper and the more posterior paraspinal prevertebral space (Fig. 1 A). Superficially, the PCS is bounded by the superficial layer of deep cervical fascia, which splits to enclose the sternomastoid and trapezius musdes [4]. Anteromedially, the PCS is separated from the carotid space by the carotid sheath. Seen from the side, the PCS has the appearance of a posteriorly tilted triangle (Fig. 1 B). The main contents of the PCS are the spinal accessory lymph node chain, the spinal accessory nerve, and fat [5, 6]. As the contents of the PCS are limited, the differential diagnosis of diseases affecting the PCS is also limited. The principal abnormality occurring in this space arises from involvement of the spinal accessory lymph node chain. Notable
Downloaded from www.ajronline.org by 178.77.154.16 on 11/14/15 from IP address 178.77.154.16. Copyright ARRS. For personal use only; all rights reserved
AJR:157,
July 1991
NORMAL
AND
DISEASED
exceptions to this pattern of PCS nodal involvement include lesions arising from the fat of the PCS (lipoma and liposarcoma) and congenital lesions (cystic hygroma and branchial cleft cysts) [7]. The most common disease of the PCS is metastatic squamous cell carcinoma. Spinal accessory chain lymphadenopathy within the PCS is a classic manifestation of an occult nasopharyngeal mucosal space malignancy [8, 9]. Nevertheless, in our series lymphadenopathy in the PCS occurred more often as a result of lesions elsewhere in the pharyngeal mucosal space and the larynx, owing to their greater overall frequency. Lymphoma, both Hodgkin and non-Hodgkin types, was represented frequently in our series. The disease typically occurred intranodally within the PCS, although extranodal, extralymphatic deposits were seen also [1 0]. Lymphomatous deposits typically showed no evidence of necrosis unless previously treated or of high grade. Metastatic lymphadenopathy tended to be seen in other lymph node chains in the adjacent neck in the majority of cases, especially in patients with both non-Hodgkin and Hodgkin lymphoma and metastatic squamous cell carcinoma. In one patient with metastatic adenocarcinoma of the lung, PCS lymphadenopathy was confined to the immediate supraclavicular region. In such patients with predominantly low PCS lymphadenopathy, the primary tumor should be sought in the thyroid, thorax, or abdomen [4, 9]. Inflammatory lymphadenopathy also is common in the PCS. Inflammatory processes begin with enlargement of a lymph node and may progress if virulent or untreated to suppuration within the lymph node. If the process continues to go untreated, spread through the capsule of the lymph node is seen, forming an abscess in the PCS. Suppurative lymphadenopathy tends to occur with unusual pathogens. Those identified in our study were tularemia, atypical mycobacteria, and cat scratch fever. Congenital lesions are seen not infrequently in the PCS. Most commonly these are multiseptated lesions in the cystic hygroma/lymphangioma spectrum [1 1 12]. The branchial cleft cysts seen in this study were atypical in that they were centered in the PCS, not the submandibular space where the second branchial cleft cysts are found [7]. Although difficult ,
to prove,
it is tempting
to speculate
that these
PCS branchial
POSTERIOR
CERVICAL
SPACE
165
cleft cysts are actually third branchial cleft cysts. Benign tumors of the PCS are rare. Lipoma is seen most often. Neurofibromas and hemangiomas also can be found in this space. These lesions also are derived from the tissues normally found in the PCS. Three kinds of pseudomasses were identified in the PCS. The term pseudomass is used when there is a clinically palpable lesion of the posterior triangle and CT or MR identifies it as a nonsurgical abnormality outside of the PCS. Cervical ribs and prominent cervical transverse processes are the common bony pseudomasses. Another clinical pseudomass is found in levator scapulae hypertrophy commonly seen after radical neck dissection with sacrifice of the spinal accessory nerve. The hypertrophied levator scapulae muscle can cause concern for tumor recurrence in the posterior triangle of the neck [4].
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