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Differential diagnosis of cervical lymph nodes in head and neck cancer by ultrasonography
Auris Nasus Larynx 26 (1999) 331 – 336
Differential diagnosis of cervical lymph nodes in head and neck cancer by ultrasonography Yousuke Takeuchi *, Haruhiko Suzuki, Ken Omura, Takeo Shigehara, Tomomi Yamashita, Kazuhiko Okumura, Fumiyuki Shimada Department of Head and Neck Surgery, Chiba Cancer Center Hospital, 666 -2 Nitona, Chuo-ku, Chiba 260 -8717, Japan Received 30 May 1998; received in revised form 27 July 1998; accepted 25 September 1998
Abstract Objecti6e: Determination of whether an enlarged cervical lymph node is metastatic or not is clinically important in head and neck oncology. Differential diagnosis of the lymph node, however, is still a diagnostic problem. The purpose of this study is to clarify the ultrasonographic findings of the metastatic lymph nodes of head and neck squamous cell carcinoma and to establish the criteria. Methods: We investigated 36 metastatic lymph nodes in head and neck squamous cell carcinoma and 24 non-metastatic nodes in benign disease with a 10-MHz transducer. We examined the size, shape, and internal echo (echo level, punctate bright echogenic spots, hilus echogenic line, cystic pattern) of these nodes. Based on this investigation, we evaluated 70 lymph nodes from 25 other patients by ultrasonography. Results: The short axis diameter and shape of metastatic nodes were larger and rounder than those of non-metastatic ones. Of the metastatic nodes, 69% showed hypoechoic and 31% isoechoic levels, and 78% exhibited punctate bright echogenic spots. Of the non-metastatic nodes, 92% showed hypoechoic and 8% isoechoic levels, and none of them showed the spots. The hilus echogenic line was not present in any metastatic node, but it was seen in 58% of non-metastatic ones. Of the metastatic nodes, 19% exhibited a cystic pattern; none of the non-metastatic nodes showed the pattern. According to our criteria based on these results, the accuracy rate was 98.6% (69/70). The sensitivity and specificity were 97.2% (35/36) and 100% (34/34), respectively. The false positive rate and the false negative rate were 0% (0/70) and 1.4% (1/70), respectively. Conclusion: Internal echo findings and shape of lymph nodes can be an important diagnostic tool, and our ultrasonographical criteria of the lymph nodes are very useful for the differential diagnosis of the cervical lymph nodes. © 1999 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Ultrasonography; Lymph node; Metastasis; Head and neck cancer; Squamous cell carcinoma
* Corresponding author. Tel.: +81-43-264-5431; fax: +81-43-262-8680. 0385-8146/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 3 8 5 - 8 1 4 6 ( 9 8 ) 0 0 0 7 1 - 6
332
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
1. Introduction Since the presence or absence of cervical lymph node metastasis in patients with head and neck cancer affects the planning of treatment, it is clinically important to diagnose whether an enlarged lymph node is metastatic or not. Differentiation of the enlarged lymph node, however, is still a diagnostic problem in head and neck oncology. Previously, ultrasonographic evaluation of a lymph node was based primarily on its size and shape [1,2], without much regard for its internal structure. Recently, however, the availability of high-frequency probe has made consideration of internal structure possible [3]. The findings of metastatic lymph nodes by ultrasonography in papillary carcinoma of the thyroid gland were clearly different from those of non-metastatic ones [4]. The purpose of this study is to clarify the ultrasonographic characteristics of the metastatic lymph nodes of head and neck squamous cell carcinoma, and to establish their criteria.
2. Materials and methods We performed the following study between April 1994 and December 1996. In the first part of this study, 31 patients with previously untreated head and neck squamous cell carcinoma were examined by ultrasonography. Thirty-six of their cervical lymph nodes that were found pathologically to be metastatic after neck dissection were examined. In addition, 24 nodes that were pathologically or cytologically benign on open biopy or fine-needle aspiration biopsy from 20 patients without malignant disease were examined. The non-metastatic nodes included those that remained unchanged or decreased in size during a follow-up period of more than 6 months. Ultrasonograms were evaluated on the basis of size, shape, and internal echo, and the findings between metastatic and non-metastatic node compared. An SSD-1200 ultrasonography system with a 10-MHz mechanical sector probe (Aloka, Tokyo, Japan) was used for this investigation.
Lymph node size was assessed by measuring the long axis diameter and the short axis diameter. A long axis diameter, as defined here, is the largest diameter of the largest nodal plane. We defined a short axis diameter as the shortest diameter of the largest nodal plane that crossed at right angles to the long axis defined above. Lymph node shape was assessed by short to long axis diameter ratio (S/L). The closer the ratio to 1.00, the rounder the shape. Internal echo structures (echo level, punctate bright echogenic spot, hilus echogenic line, and cystic pattern) were evaluated. The echo level of normal sternocleidomastoid muscle was used as a standard. The echo levels of the lymph nodes was classified into two categories: isoechoic or hypoechoic. Punctate bright echogenic spots, hilus echogenic line, and cystic pattern were separated into two groups: present or absent. The significance of the differences between the results obtained for the two groups was assessed by using the Mann–Whitney test. In the second part of this study, based on our criteria from the results of the first part study, we evaluated by ultrasonography 70 lymph nodes from 25 patients with previously untreated head and neck squamous cell carcinoma. All patients had neck dissection. All lymph nodes were pathologically proved metastatic or non-metastatic.
3. Results
3.1. Size The long axis diameter of metastatic lymph nodes ranged from 8 to 70 mm, median 16.5 mm, mean 19 mm. On the other hand, that of nonmetastatic lymph nodes ranged from 8 to 23 mm, median 14.5 mm, mean 15 mm. The difference in the distribution of metastatic and non-metastatic nodes according to long axis diameter was not statistically significant (P\0.50). The short axis diameter of metastatic lymph nodes ranged from 5 to 40 mm, median of 10 mm, mean of 12 mm. On the other hand, the short axis diameter of non-metastatic lymph nodes ranged from 2 to 12 mm, median 6.5 mm, mean 6.3 mm. The difference in the distribution of metastatic
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
333
Table 1 Nodal size and shape
Meta. n=36 Non-meta. n= 24
Long axis diameter mm (median, mean)
Short axis diameter mm (median, mean)
S/L ratio (median, mean)
870 (16.5, 19)
540 (10, 12)
0.331.00 (0.62, 0.64)
823 (14.5, 15)
212 (6.5, 6.3)
0.180.73 (0.45, 0.42)
and non-metastatic nodes according to the short axis diameter was statistically significant (P B 0.0001; Table 1).
showed hypoechoic level and 8% (2/24) isoechoic (Table 2).
3.2. Shape
3.4. Punctate bright echogenic spot
The S/L ratio of metastatic lymph nodes ranged from 0.33 to 1.00, median 0.62, mean 0.64. On the other hand, the S/L ratio of nonmetastatic lymph nodes ranged from 0.18 to 0.73, median 0.45, mean 0.42. The difference in the distribution of metastatic and non-metastatic nodes according to S/L ratio was statistically significant (P B 0.0001; Table 1).
Of the 36 metastatic nodes, 78% (28/36) exhibited echogenic spots (Fig. 1). None of the 24 non-metastatic nodes showed an echogenic spot. (Table 2)
3.5. Hilus echogenic line
Of the 36 metastatic nodes, 69% (25/36) showed hypoechoic level and 31% (11/36) isoechoic (Fig. 1). Of the 24 non-metastatic nodes, 92% (22/24)
None of the 36 metastatic nodes exhibited a hilus echogenic line (Fig. 2). Of the 24 nonmetastatic nodes, 58% (14/24) showed the hilus echogenic line and 42% (10/24) no hilus line (Table 2). 3.6. Cystic pattern
Fig. 1. Ultrasonograph of metastatic lymph node. Arrow: Lymph node at the middle jugular. Transverse section. Short axis diameter was 9 mm.The S/L ratio was 0.90. Internal echo level was isoechoic. Punctate bright echogenic spot was present, but hilus echogenic line was not.
Of the 36 metastatic nodes, 19% (7/36) exhibited a cystic pattern. None of the 24 nonmetastatic nodes showed a cystic pattern (Table 2). Based on the findings of the first part, we established the criteria in Table 3 to distinguish metastatic from non-metastatic lymph nodes. In Table 4 the relationship between finding at ultrasonography according to our criteria and pathological examination are shown based on our results of the second part. The accuracy rate was 98.6% (69/70). The sensitivity and specificity were 97.2% (35/36) and 100% (34/34), respectively. The false positive and false negative rates were 0% (0/70) and 1.4% (1/70), respectively. The lymph node of the false negative had a microscopically small metastatic lesion (Fig. 3).
3.3. Echo le6el
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
334 Table 2 Internal echo
Meta. n =36 Non-meta. n = 24 a
Echo levela
Punctate bright echogenic spot
Hilus echogenic line
Cystic pattern
Iso. 31%; hypo. 69% Iso. 8%; hypo. 92%
78% 0%
0% 58%
19% 0%
Iso., isoechoic; hypo., hypoechoic.
4. Discussion Ultrasonography has proved a valuable tool for the detection of enlarged lymph nodes; however, differentiation between metastatic and nonmetastatic lymph nodes is still a diagnostic problem. Some authors have defined criteria for diagnosis of metastatic or non-metastatic nodes with ultrasonography [3,5], but they are based primarily on a node’s size and shape [1,2], rather than its internal structure. Recently, however, the use of high-frequency transducers permits a detailed sonographic analysis of the internal structure of lymph nodes [3]. We believe that more precise diagnosis of the lymph node can be made by adding the information of the internal echo to nodal size and shape. For the precise evaluation of nodal size and ratio of S/L, ultrasonography has the particular advantage over other imaging methods of allowing free rotation of the scanning plane. Our results showed no significant differences between metastatic and non-metastatic nodes in the long axis diameter, but there were marked
Fig. 2. Ultrasonograph of non-metastatic lymph node. Lymph node at the posterior triangle. Longitudinal section. Short axis diameter was 7 mm. The S/L ratio was 0.35. Internal echo level was hypoechoic. Hilus echogenic line was present, but punctate bright echogenic spot was not.
differences in the short axis diameter. The short axis diameter of the metastatic lymph node was significantly thicker than that of non-metastatic one as previously reported [1]. The metastatic lymph nodes showed a significantly higher ratio of S/L than those of the non-metastatic ones in other studies [2,5]. Metastatic lymph node more often has a round or elliptic shape, which reflects an increase in short axis diameter [6]. We, however, should make careful in evaluation of submandibular lymph nodes, because they are often round or elliptic due to chronic inflammation. Our results indicate that echo levels of metastatic lymph node are higher than non-metastatic ones. The punctate bright echogenic spot corresponds to necrotic, keratinizing, or fibrotic tissue [7]. In our study, the spots were often identified within metastatic lymph node. Absence of the spots suggests that a lymph node is non-metastatic. The spots serve as reliable criteria for differentiating metastatic lymph nodes from non-metastatic ones. We think that the cause of echogenicity of the hilus echogenic line is fatty hilar tissue contiguous with the perinodal fatty tissue, as described by Sakai et al. [8]. Our results suggest that the absence of a hilar line is a criterion for diagnosing metastasis, and the presence of a hilus echogenic line is a valid criterion of non-metastatic lymph node as another observer has reported [3]. Cystic pattern corresponds to liquefaction necrosis. Our previous study indicated that 41% (16/39) of metastatic lymph nodes in papillary carcinoma of the thyroid gland showed the cystic pattern [4]. We, however, should be careful evaluating lymph nodes with cystic pattern, since the lymph node of lymphadenitis with abscess also shows cystic pattern.
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
335
Table 3 Criteria of metastatic and non-metastatic lymph node by ultrasonography Echo levela
Shape Meta. Non-meta. a
Roundelliptic hypo.iso. Flatelliptic Hypo.
Punctate bright echogenic spot
Hilus echogenic line
Cystic pattern
(+) (−)
(−) (+)
(+) (−)
Iso., isoechoic; hypo., hypoechoic.
The sensitivity, specificity, and accuracy in our study are higher than those in other reports [7,9,10]. If the differentiation of lymph node is difficult by palpation, ultrasonography or X-CT, we should perform fine-needle aspiration cytological examination. However, selection of the correct lymph node to aspirate is very important. Ultrasonography is very advantageous in this selection. Moreover, ultrasonography-guided fineneedle aspiration cytological examination is precise and avoids puncturing the adjacent major vessels.
5. Conclusion The internal echo findings of lymph node can also be important diagnostic criteria. Ultrasonography is a very useful method for the differential diagnosis of the cervical lymph nodes. Ultrasonography cannot, however, detect a microscopic metastatic lesion in a lymph node. In the future, we need to improve the detection rate of smaller lymph nodes and microscopic lesions. Table 4 Finding at ultrasonography versus pathological examinationa Finding at ultrasonography
Positive Negative Total a
Pathological findings
Positive
Negative
Total
35 1 36
0 34 34
35 35 70
Accuracy= 98.6%; sensitivity = 97.2%; specificity = 100%.
Fig. 3. Microscopical metastatic lesion in the false negative lymph node. A. Arrow (H – E, × 2.5), B. Higher magnification of the lesion (H – E, ×25).
336
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
References [1] Bruneton JN, Roux P, Caramella E, Demard F, Vallicioni J, Chauvel P. Ear nose and throat cancer: ultrasound diagnosis of metastasis to cervical lymph nodes. Radiology 1984;152:771–3. [2] Tohnosu N, Onoda S, Isono K. Ultrasonographic evaluation of cervical lymph node metastases in esophageal cancer with special reference to the relationship between the short to long axis ratio (S/L) and the cancer content. J Ultrasound Med 1989;17:101–7. [3] Rubaltelli L, Proto E, Salmaso R, Bortoletto P, Candiani F, Cagol P. Sonography of abnormal lymph nodes in vitro: correlation of sonographic and histologic findings. American Journal of Roentgenology 1990;155:1241–4. [4] Takeuchi Y, Suzuki H, Omura K, Okumura K, Yanai C. Ultrasonographic evaluation of metastatic cervical lymph nodes in papillary carcinoma of the thyroid gland. Head Neck Cancer 1997;23:66–71. [5] Vassallo P, Wernecke K, Roos N, Peters PE. Differentiation of benign from malignant superficial lymphadenopa-
[6]
[7]
[8]
[9]
[10]
thy:the role of high-resolution US. Radiology 1992;183:215 – 20. Sutton RT, Reading CC, Charboneau JW, James EM, Grant CS, Hay ID. US-guided biopsy of neck mass in postoperative management of patients with thyroid cancer. Radiology 1988;168:769 – 72. van den Brekel MWM, Castelijns JA, Stel HV, Luth WJ, Valk J, van der Waal I, et al. Occult metastatic neck disease: detection with US and US-guided fine-needle aspiration cytology. Radiology 1991;180:457 – 61. Sakai F, Kiyono K, Sone S, Kondo Y, Oguchi M, Watanabe T, et al. Ultrasonic evaluation of cervical metastatic lymphadenopathy. J Ultrasound Med 1988;7:305 – 10. Baatenburg de Jong RJ, Rongen RJ, Lameris JS, Harthoorn M, Verwoerd CDA, Knegt P. Metastatic neck disease. Palpation vs ultrasound examination. Arch Otolaryngol Head Neck Surg 1989;115:689 – 90. Takashima S, Sone S, Nomura N, Tomiyama N, Kobayashi T, Nakamura H. Nonpalpable lymph nodes of the neck: assessment with US and US-guided fine needle aspiration biopsy. J Clin Ultrasound 1997;25:283 – 92.
Differential diagnosis of cervical lymph nodes in head and neck cancer by ultrasonography Yousuke Takeuchi *, Haruhiko Suzuki, Ken Omura, Takeo Shigehara, Tomomi Yamashita, Kazuhiko Okumura, Fumiyuki Shimada Department of Head and Neck Surgery, Chiba Cancer Center Hospital, 666 -2 Nitona, Chuo-ku, Chiba 260 -8717, Japan Received 30 May 1998; received in revised form 27 July 1998; accepted 25 September 1998
Abstract Objecti6e: Determination of whether an enlarged cervical lymph node is metastatic or not is clinically important in head and neck oncology. Differential diagnosis of the lymph node, however, is still a diagnostic problem. The purpose of this study is to clarify the ultrasonographic findings of the metastatic lymph nodes of head and neck squamous cell carcinoma and to establish the criteria. Methods: We investigated 36 metastatic lymph nodes in head and neck squamous cell carcinoma and 24 non-metastatic nodes in benign disease with a 10-MHz transducer. We examined the size, shape, and internal echo (echo level, punctate bright echogenic spots, hilus echogenic line, cystic pattern) of these nodes. Based on this investigation, we evaluated 70 lymph nodes from 25 other patients by ultrasonography. Results: The short axis diameter and shape of metastatic nodes were larger and rounder than those of non-metastatic ones. Of the metastatic nodes, 69% showed hypoechoic and 31% isoechoic levels, and 78% exhibited punctate bright echogenic spots. Of the non-metastatic nodes, 92% showed hypoechoic and 8% isoechoic levels, and none of them showed the spots. The hilus echogenic line was not present in any metastatic node, but it was seen in 58% of non-metastatic ones. Of the metastatic nodes, 19% exhibited a cystic pattern; none of the non-metastatic nodes showed the pattern. According to our criteria based on these results, the accuracy rate was 98.6% (69/70). The sensitivity and specificity were 97.2% (35/36) and 100% (34/34), respectively. The false positive rate and the false negative rate were 0% (0/70) and 1.4% (1/70), respectively. Conclusion: Internal echo findings and shape of lymph nodes can be an important diagnostic tool, and our ultrasonographical criteria of the lymph nodes are very useful for the differential diagnosis of the cervical lymph nodes. © 1999 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Ultrasonography; Lymph node; Metastasis; Head and neck cancer; Squamous cell carcinoma
* Corresponding author. Tel.: +81-43-264-5431; fax: +81-43-262-8680. 0385-8146/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 3 8 5 - 8 1 4 6 ( 9 8 ) 0 0 0 7 1 - 6
332
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
1. Introduction Since the presence or absence of cervical lymph node metastasis in patients with head and neck cancer affects the planning of treatment, it is clinically important to diagnose whether an enlarged lymph node is metastatic or not. Differentiation of the enlarged lymph node, however, is still a diagnostic problem in head and neck oncology. Previously, ultrasonographic evaluation of a lymph node was based primarily on its size and shape [1,2], without much regard for its internal structure. Recently, however, the availability of high-frequency probe has made consideration of internal structure possible [3]. The findings of metastatic lymph nodes by ultrasonography in papillary carcinoma of the thyroid gland were clearly different from those of non-metastatic ones [4]. The purpose of this study is to clarify the ultrasonographic characteristics of the metastatic lymph nodes of head and neck squamous cell carcinoma, and to establish their criteria.
2. Materials and methods We performed the following study between April 1994 and December 1996. In the first part of this study, 31 patients with previously untreated head and neck squamous cell carcinoma were examined by ultrasonography. Thirty-six of their cervical lymph nodes that were found pathologically to be metastatic after neck dissection were examined. In addition, 24 nodes that were pathologically or cytologically benign on open biopy or fine-needle aspiration biopsy from 20 patients without malignant disease were examined. The non-metastatic nodes included those that remained unchanged or decreased in size during a follow-up period of more than 6 months. Ultrasonograms were evaluated on the basis of size, shape, and internal echo, and the findings between metastatic and non-metastatic node compared. An SSD-1200 ultrasonography system with a 10-MHz mechanical sector probe (Aloka, Tokyo, Japan) was used for this investigation.
Lymph node size was assessed by measuring the long axis diameter and the short axis diameter. A long axis diameter, as defined here, is the largest diameter of the largest nodal plane. We defined a short axis diameter as the shortest diameter of the largest nodal plane that crossed at right angles to the long axis defined above. Lymph node shape was assessed by short to long axis diameter ratio (S/L). The closer the ratio to 1.00, the rounder the shape. Internal echo structures (echo level, punctate bright echogenic spot, hilus echogenic line, and cystic pattern) were evaluated. The echo level of normal sternocleidomastoid muscle was used as a standard. The echo levels of the lymph nodes was classified into two categories: isoechoic or hypoechoic. Punctate bright echogenic spots, hilus echogenic line, and cystic pattern were separated into two groups: present or absent. The significance of the differences between the results obtained for the two groups was assessed by using the Mann–Whitney test. In the second part of this study, based on our criteria from the results of the first part study, we evaluated by ultrasonography 70 lymph nodes from 25 patients with previously untreated head and neck squamous cell carcinoma. All patients had neck dissection. All lymph nodes were pathologically proved metastatic or non-metastatic.
3. Results
3.1. Size The long axis diameter of metastatic lymph nodes ranged from 8 to 70 mm, median 16.5 mm, mean 19 mm. On the other hand, that of nonmetastatic lymph nodes ranged from 8 to 23 mm, median 14.5 mm, mean 15 mm. The difference in the distribution of metastatic and non-metastatic nodes according to long axis diameter was not statistically significant (P\0.50). The short axis diameter of metastatic lymph nodes ranged from 5 to 40 mm, median of 10 mm, mean of 12 mm. On the other hand, the short axis diameter of non-metastatic lymph nodes ranged from 2 to 12 mm, median 6.5 mm, mean 6.3 mm. The difference in the distribution of metastatic
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
333
Table 1 Nodal size and shape
Meta. n=36 Non-meta. n= 24
Long axis diameter mm (median, mean)
Short axis diameter mm (median, mean)
S/L ratio (median, mean)
870 (16.5, 19)
540 (10, 12)
0.331.00 (0.62, 0.64)
823 (14.5, 15)
212 (6.5, 6.3)
0.180.73 (0.45, 0.42)
and non-metastatic nodes according to the short axis diameter was statistically significant (P B 0.0001; Table 1).
showed hypoechoic level and 8% (2/24) isoechoic (Table 2).
3.2. Shape
3.4. Punctate bright echogenic spot
The S/L ratio of metastatic lymph nodes ranged from 0.33 to 1.00, median 0.62, mean 0.64. On the other hand, the S/L ratio of nonmetastatic lymph nodes ranged from 0.18 to 0.73, median 0.45, mean 0.42. The difference in the distribution of metastatic and non-metastatic nodes according to S/L ratio was statistically significant (P B 0.0001; Table 1).
Of the 36 metastatic nodes, 78% (28/36) exhibited echogenic spots (Fig. 1). None of the 24 non-metastatic nodes showed an echogenic spot. (Table 2)
3.5. Hilus echogenic line
Of the 36 metastatic nodes, 69% (25/36) showed hypoechoic level and 31% (11/36) isoechoic (Fig. 1). Of the 24 non-metastatic nodes, 92% (22/24)
None of the 36 metastatic nodes exhibited a hilus echogenic line (Fig. 2). Of the 24 nonmetastatic nodes, 58% (14/24) showed the hilus echogenic line and 42% (10/24) no hilus line (Table 2). 3.6. Cystic pattern
Fig. 1. Ultrasonograph of metastatic lymph node. Arrow: Lymph node at the middle jugular. Transverse section. Short axis diameter was 9 mm.The S/L ratio was 0.90. Internal echo level was isoechoic. Punctate bright echogenic spot was present, but hilus echogenic line was not.
Of the 36 metastatic nodes, 19% (7/36) exhibited a cystic pattern. None of the 24 nonmetastatic nodes showed a cystic pattern (Table 2). Based on the findings of the first part, we established the criteria in Table 3 to distinguish metastatic from non-metastatic lymph nodes. In Table 4 the relationship between finding at ultrasonography according to our criteria and pathological examination are shown based on our results of the second part. The accuracy rate was 98.6% (69/70). The sensitivity and specificity were 97.2% (35/36) and 100% (34/34), respectively. The false positive and false negative rates were 0% (0/70) and 1.4% (1/70), respectively. The lymph node of the false negative had a microscopically small metastatic lesion (Fig. 3).
3.3. Echo le6el
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
334 Table 2 Internal echo
Meta. n =36 Non-meta. n = 24 a
Echo levela
Punctate bright echogenic spot
Hilus echogenic line
Cystic pattern
Iso. 31%; hypo. 69% Iso. 8%; hypo. 92%
78% 0%
0% 58%
19% 0%
Iso., isoechoic; hypo., hypoechoic.
4. Discussion Ultrasonography has proved a valuable tool for the detection of enlarged lymph nodes; however, differentiation between metastatic and nonmetastatic lymph nodes is still a diagnostic problem. Some authors have defined criteria for diagnosis of metastatic or non-metastatic nodes with ultrasonography [3,5], but they are based primarily on a node’s size and shape [1,2], rather than its internal structure. Recently, however, the use of high-frequency transducers permits a detailed sonographic analysis of the internal structure of lymph nodes [3]. We believe that more precise diagnosis of the lymph node can be made by adding the information of the internal echo to nodal size and shape. For the precise evaluation of nodal size and ratio of S/L, ultrasonography has the particular advantage over other imaging methods of allowing free rotation of the scanning plane. Our results showed no significant differences between metastatic and non-metastatic nodes in the long axis diameter, but there were marked
Fig. 2. Ultrasonograph of non-metastatic lymph node. Lymph node at the posterior triangle. Longitudinal section. Short axis diameter was 7 mm. The S/L ratio was 0.35. Internal echo level was hypoechoic. Hilus echogenic line was present, but punctate bright echogenic spot was not.
differences in the short axis diameter. The short axis diameter of the metastatic lymph node was significantly thicker than that of non-metastatic one as previously reported [1]. The metastatic lymph nodes showed a significantly higher ratio of S/L than those of the non-metastatic ones in other studies [2,5]. Metastatic lymph node more often has a round or elliptic shape, which reflects an increase in short axis diameter [6]. We, however, should make careful in evaluation of submandibular lymph nodes, because they are often round or elliptic due to chronic inflammation. Our results indicate that echo levels of metastatic lymph node are higher than non-metastatic ones. The punctate bright echogenic spot corresponds to necrotic, keratinizing, or fibrotic tissue [7]. In our study, the spots were often identified within metastatic lymph node. Absence of the spots suggests that a lymph node is non-metastatic. The spots serve as reliable criteria for differentiating metastatic lymph nodes from non-metastatic ones. We think that the cause of echogenicity of the hilus echogenic line is fatty hilar tissue contiguous with the perinodal fatty tissue, as described by Sakai et al. [8]. Our results suggest that the absence of a hilar line is a criterion for diagnosing metastasis, and the presence of a hilus echogenic line is a valid criterion of non-metastatic lymph node as another observer has reported [3]. Cystic pattern corresponds to liquefaction necrosis. Our previous study indicated that 41% (16/39) of metastatic lymph nodes in papillary carcinoma of the thyroid gland showed the cystic pattern [4]. We, however, should be careful evaluating lymph nodes with cystic pattern, since the lymph node of lymphadenitis with abscess also shows cystic pattern.
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
335
Table 3 Criteria of metastatic and non-metastatic lymph node by ultrasonography Echo levela
Shape Meta. Non-meta. a
Roundelliptic hypo.iso. Flatelliptic Hypo.
Punctate bright echogenic spot
Hilus echogenic line
Cystic pattern
(+) (−)
(−) (+)
(+) (−)
Iso., isoechoic; hypo., hypoechoic.
The sensitivity, specificity, and accuracy in our study are higher than those in other reports [7,9,10]. If the differentiation of lymph node is difficult by palpation, ultrasonography or X-CT, we should perform fine-needle aspiration cytological examination. However, selection of the correct lymph node to aspirate is very important. Ultrasonography is very advantageous in this selection. Moreover, ultrasonography-guided fineneedle aspiration cytological examination is precise and avoids puncturing the adjacent major vessels.
5. Conclusion The internal echo findings of lymph node can also be important diagnostic criteria. Ultrasonography is a very useful method for the differential diagnosis of the cervical lymph nodes. Ultrasonography cannot, however, detect a microscopic metastatic lesion in a lymph node. In the future, we need to improve the detection rate of smaller lymph nodes and microscopic lesions. Table 4 Finding at ultrasonography versus pathological examinationa Finding at ultrasonography
Positive Negative Total a
Pathological findings
Positive
Negative
Total
35 1 36
0 34 34
35 35 70
Accuracy= 98.6%; sensitivity = 97.2%; specificity = 100%.
Fig. 3. Microscopical metastatic lesion in the false negative lymph node. A. Arrow (H – E, × 2.5), B. Higher magnification of the lesion (H – E, ×25).
336
Y. Takeuchi et al. / Auris Nasus Larynx 26 (1999) 331–336
References [1] Bruneton JN, Roux P, Caramella E, Demard F, Vallicioni J, Chauvel P. Ear nose and throat cancer: ultrasound diagnosis of metastasis to cervical lymph nodes. Radiology 1984;152:771–3. [2] Tohnosu N, Onoda S, Isono K. Ultrasonographic evaluation of cervical lymph node metastases in esophageal cancer with special reference to the relationship between the short to long axis ratio (S/L) and the cancer content. J Ultrasound Med 1989;17:101–7. [3] Rubaltelli L, Proto E, Salmaso R, Bortoletto P, Candiani F, Cagol P. Sonography of abnormal lymph nodes in vitro: correlation of sonographic and histologic findings. American Journal of Roentgenology 1990;155:1241–4. [4] Takeuchi Y, Suzuki H, Omura K, Okumura K, Yanai C. Ultrasonographic evaluation of metastatic cervical lymph nodes in papillary carcinoma of the thyroid gland. Head Neck Cancer 1997;23:66–71. [5] Vassallo P, Wernecke K, Roos N, Peters PE. Differentiation of benign from malignant superficial lymphadenopa-
[6]
[7]
[8]
[9]
[10]
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