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Study |

Efficacy of Diagnostic Ultrasonography of Lipomas, Epidermal Cysts, and Ganglions FREE

Yoshihiro Kuwano, MD, PhD; Kazuho Ishizaki, CT; Rei Watanabe, MD, PhD; Hiroko Nanko, MD, PhD
[+] Author Affiliations

Author Affiliations: Departments of Dermatology (Drs Kuwano, Watanabe, and Nanko) and Clinical Laboratories (Mr Ishizaki), Tokyo Kousei-Nenkin Hospital, and Department of Dermatology, University of Tokyo (Drs Kuwano and Watanabe), Tokyo, Japan.


Arch Dermatol. 2009;145(7):761-764. doi:10.1001/archdermatol.2009.61.
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Published online

Objective  To determine the efficacy of ultrasonography for the diagnosis of subcutaneous benign lesions.

Design  Retrospective study.

Setting  Tokyo Kousei-Nenkin Hospital, Tokyo, Japan.

Patients  The study included 183 patients with subcutaneous benign lesions who underwent ultrasonography and then received a pathologic diagnosis after surgery.

Main Outcome Measures  The study evaluated the number of cases in which the preoperative diagnosis after ultrasonography or just after palpation agreed with the pathologic diagnosis.

Results  Ultrasonography significantly increased the preoperative diagnostic yield of subcutaneous benign lesions (after palpation, 29%; after ultrasonography, 46%; P < .001). The sensitivity for the diagnosis of lipoma (after palpation, 54.8%; after ultrasonography, 88.1%; P < .01) and the specificity for the diagnosis of epidermal cyst (after palpation, 93.5%; after ultrasonography, 99.3%; P < .05) significantly increased after ultrasonography. The sensitivity for the diagnosis of epidermal cyst and ganglion also tended to increase after ultrasonography.

Conclusion  The study results suggest that ultrasonography is useful for the preoperative examination of subcutaneous benign lesions.

Figures in this Article

Ultrasonography is an important diagnostic tool in many aspects of clinical medicine. It is a noninvasive method of examination that provides high-resolution images in real time. The instrument for ultrasonography is generally cheaper than that for computed tomography or magnetic resonance imaging and can sometimes even be found in small clinics in Japan.

There are 2 basic types of ultrasonography with dermatologic applications.1 Ultrasonography with 20-MHz probes is used to obtain preoperative information about tumor thickness in superficial skin tumors, including melanoma, basal cell carcinoma, and squamous cell carcinoma.1,2 Scanning with 20-MHz probes is also used to measure skin thickness during the treatment of inflammatory diseases such as scleroderma or psoriasis.35 Therefore, ultrasonography is an important diagnostic tool in the field of dermatology.1,6 Furthermore, probes with a frequency higher than 20 MHz (eg, 50 MHz) can be used to examine the skin and skin lesions. In contrast to the well-established role of the high-frequency ultrasound systems, the use of ultrasound scanning with 7.5- to 10-MHz probes is not as widespread, although promising results have been reported from specialized diagnostic units, especially for the assessment of peripheral lymph nodes and subcutaneous tumors.1,710 Ultrasonography of subcutaneous tumors is useful for acquiring information about the nature, size, and depth of the lesions as well as their relationship to adjacent vessels and other structures. An elongated isoechoic or echogenic mass in the subcutaneous tissues should suggest the diagnosis of lipoma.11 The echo phenomena caused by the tumor are very much like those of subcutaneous fat tissue.12 The existence of striated echoes in the tumor corresponding to the septa increases the possibility of lipoma. Epidermal cysts have the typical characteristics of cysts; ie, they have a round to oval structure along with the phenomena of dorsal acoustic amplification and lateral shadowing.6,1214 They also show central echoes of nonanechoic intensity owing to their contents as well as partial indentation to the dermis when they are subcutaneous. Subcutaneous metastases of malignant melanoma often show a spheroidal lesion that demonstrates partial or even extensive vascularization,15 and they appear almost anechoic, often with a dorsal acoustic attenuation, while subcutaneous benign tumors appear rather echogenic.12 These features are useful for preoperative diagnosis. However, introduction of the ultrasound machine and the frequency of its use vary substantially by country or region. In Japan, the decision whether or not to use ultrasonography in cases involving subcutaneous lesions differs considerably, even among dermatologists who are working in hospitals of similar scale. Some dermatologists may be anxious about the efficacy of ultrasonography. In this study, we examined the number of cases in which the preoperative diagnosis after ultrasonography agreed with the pathologic diagnosis. Then, we compared this number with the number of cases in which the clinical diagnosis before ultrasonography corresponded to the pathologic diagnosis.

PATIENTS

The study group comprised 183 patients with subcutaneous benign lesions and no changes in skin surface who underwent ultrasonography and received a pathologic diagnosis after surgery at Tokyo Kousei-Nenkin Hospital, Tokyo, Japan, from 1998 to 2006 (Table 1). Ultrasonography was not performed in cases in which the diagnosis of the lesions was easy, ie, made simply by clinical examination, as in an epidermal cyst with a central keratin-filled punctum. Therefore, such lesions were not included in our study. There were no patients with malignant subcutaneous tumors. Institutional review board approval was obtained for data collection and outcome analysis of cases in the institutional database.

Table Graphic Jump LocationTable 1. Characteristics of 183 Patients With Subcutaneous Benign Lesions
PALPATION AND ULTRASONOGRAPHY

First, patients with subcutaneous lesions were examined clinically, and when the diagnosis was not easy (ie, made just with palpation), ultrasonography was performed. When the lesions were examined with palpation, if there were characteristic findings and 1 particular disease was thought to be obvious compared with others, the clinical diagnosis was written on the medical record. If the diagnosis was indeterminable, with various differential diagnoses, that was written on the medical record as well. Then, ultrasonography was performed with a commercially available high-performance ultrasound system (Aplio SSA-770A; Toshiba Medical, Tokyo, Japan) and a 8.5-MHz linear transducer. The diagnosis after ultrasonography was also written on the medical record before surgery. An elongated isoechoic mass with striated echoes corresponding to the septa in the subcutaneous tissues was diagnosed as a lipoma (Figure 1A).11,12 A round to oval nonanechoic mass with partial indentation to the dermis and with dorsal acoustic amplification was diagnosed as an epidermal cyst (Figure 1B).6,1214 An anechoic amorphous mass with a relatively sharp border and joint communication was diagnosed as a ganglion (Figure 1C).16

Place holder to copy figure label and caption
Figure 1.

Typical ultrasonographic images of lipoma (A), epidermal cyst (B), and ganglion (C). A, An elongated isoechoic mass is evident in the subcutaneous tissue. There are striated echoes in the mass (arrow). B, A round to oval nonanechoic mass with a partial indentation to the dermis, dorsal acoustic amplification, and lateral shadows. C, An anechoic amorphous mass with a relatively sharp border and protrusion toward the joint (arrow). Arrowheads indicate masses.

Graphic Jump Location
STATISTICAL ANALYSIS

The differences between the diagnostic accuracy just after palpation and the accuracy after ultrasonographic examination were tested using the Fisher exact test with the Bonferroni correction. The differences between the sensitivity and the specificity just after palpation and after ultrasonographic examination were tested using the McNemar test with the Bonferroni correction for multiple testing against the plural kind of tumors. P values of less than .05 were considered statistically significant. The sensitivities and specificities are shown as percentages (95% confidence intervals [CIs]) in the text.

ULTRASONOGRAPHY AND DIAGNOSTIC ACCURACY

First, we investigated the diagnostic accuracy just after palpation and after ultrasonography (Table 2). The number of cases in which the preoperative diagnosis agreed with the pathologic diagnosis was significantly higher after ultrasonography than after palpation (after ultrasonography, 85 cases [46%]; after palpation, 53 cases [29%]; P < .001). Also, the number of cases in which the preoperative diagnosis disagreed with the pathologic diagnosis was significantly lower after ultrasonography (after ultrasonography, 4 cases [2%]; after palpation, 16 cases [9%]; P < .01). Therefore, we found that ultrasonography significantly increased diagnostic accuracy in the examination of subcutaneous benign lesions.

Table Graphic Jump LocationTable 2. Comparison of Diagnostic Accuracy in the Examination of 183 Subcutaneous Benign Lesions
DIAGNOSTIC ACCURACY WITH ULTRASONOGRAPHY FOR EACH TUMOR

To clarify which tumors could best be detected by ultrasonography, we also examined the diagnostic accuracy for each tumor. Tumors with a large number of cases were classified according to lesion type, and the diagnostic accuracy was counted for each tumor (Table 3). The other, miscellaneous lesions, which were too few to analyze, were classified as “others” in the table. The lesions for which the suggested diagnosis agreed with the pathologic diagnosis among those classified as others were schwannoma, calcifying epithelioma, and thrombus. Higher diagnostic capabilities were shown after ultrasonography than after palpation in each tumor. Therefore, we concluded that ultrasonography is useful for diagnosing the broad range of benign tumors. Next, we investigated the sensitivity and specificity for the diagnosis of each subcutaneous benign tumor (Figure 2). Concerning lipoma, the sensitivity after ultrasonography was significantly higher than that just after palpation (after palpation, 54.8% [95% CI, 38.7%-70.2%]; after ultrasonography, 88.1% [95% CI, 74.4%-96.0%]; P < .01). The sensitivity after ultrasonography also tended to be higher than that after palpation with regard to epidermal cyst or ganglion (epidermal cyst: after palpation, 43.2% [95% CI, 28.4%-59.0%]; after ultrasonography, 65.9% [95% CI, 50.1%-79.5%]) (ganglion: after palpation, 27.8% [9.7%-53.5%]; after ultrasonography, 38.9% [95% CI, 17.3%-64.3%]). Also, while both palpation and ultrasonography showed high specificity for epidermal cyst, the specificity after ultrasonography was significantly higher than after palpation as well (epidermal cyst: after palpation, 93.5% [95% CI, 88.1%-97.0%]; after ultrasonography, 99.3% [95% CI, 96.1%-100%]; P < .05) (lipoma: after palpation, 97.9% [95% CI, 93.9%-99.%]; after ultrasonography, 99.3% [95% CI, 96.1%-100%]) (ganglion: after palpation, 100% [95% CI, 97.8%-100%]; after ultrasonography, 100% [95% CI, 97.8%-100%]). We also calculated the positive and negative likelihood ratios (Table 4). Ultrasonography also improved the positive and negative likelihood ratios for each tumor. These data suggest that ultrasonography greatly improves diagnostic accuracy for subcutaneous benign tumors.

Place holder to copy figure label and caption
Figure 2.

Sensitivity and specificity for the diagnosis of subcutaneous benign tumors. The sensitivity and the specificity for the diagnosis of lipoma, epidermal cyst, and ganglion were determined. The data are shown as percentages, and the error bars represent 95% confidence intervals. The asterisks indicate the significant difference between the sensitivity or the specificity after palpation and after ultrasonography (P < .05).

Graphic Jump Location
Table Graphic Jump LocationTable 3. Diagnostic Accuracy for Each Disease
Table Graphic Jump LocationTable 4. Positive and Negative Likelihood Ratios for the Diagnosis of Subcutaneous Benign Tumors

In the current study, we investigated the diagnostic accuracy of subcutaneous benign tumors after ultrasonography and compared this accuracy with that just after palpation. Notably, the diagnostic accuracy after ultrasonography was significantly greater than after palpation (Table 2). Improvement of diagnostic accuracy was shown in a variety of lesions (Table 3). Next, the sensitivity, specificity, and positive and negative likelihood ratios were determined for each tumor that had a large number of cases, and we found that ultrasonography increased sensitivity and specificity and improved the positive and negative likelihood ratios (Figure 2 and Table 4). These data stongly support the usefulness of ultrasonography for the preoperative diagnosis of subcutaneous benign lesions. Some small subcutaneous benign lesions may be removed in an in-office procedure. However, when the diagnosis is uncertain, patients with very small lesions are typically referred to a hospital for surgery. The improvement of diagnostic ability with ultrasonography may lead to an increase in the number of patients who require only an in-office procedure.

Ultrasound with a frequency higher than 20 MHz can be considered high frequency and is acceptable for examination of the skin or skin lesions. Ultrasound with a lower frequency (8.5 MHz was used in this study) is not as precise, but as only subcutaneous benign lesions were examined in our study, the lower frequency was adequate. Metastasis of a malignant tumor often demonstrates an oval mass with dorsal acoustic attenuation (the image shown in Figure 1B could also represent metastasis of a malignant tumor, eg, a melanoma). While the echogenicity of the mass can indicate that the mass is benign,12 the anamnesis and clinical symptoms are also important, and histologic analysis is still the criterion standard for differentiation.15

Inampudi et al17 demonstrated the low accuracy of ultrasonography in the diagnosis of soft-tissue lipomas (sensitivity, 40%-52%; specificity, 64%-86%). Intramuscular lipomas are relatively difficult to diagnose using ultrasonography. Therefore, the difference in accuracy between their data and ours may have occurred because their study included a large number of intramuscular lipomas. The use of ultrasonographic and histologic findings as the standard of reference may be a source of selection bias, as atypical or unusual masses may be more likely to undergo ultrasound examination and be removed. Thus, both the sensitivity and the specificity may actually be greater in the actual clinical situation than they appeared to be in our study because of this potential selection bias. Furthermore, ultrasonography and palpation were not independently performed in this study. Therefore, the respective diagnostic value of ultrasonography cannot be calculated. However, the relative improvement of the diagnostic accuracy after ultrasonography still offers valuable insight regarding the importance of ultrasonography. In conclusion, ultrasonography of subcutaneous benign lesions greatly increases the reliability of preoperative diagnosis and is useful for preoperative examination.

Correspondence: Yoshihiro Kuwano, MD, PhD, Department of Dermatology, Tokyo Kousei-Nenkin Hospital, 5-1 Tsukudo-cho, Shinjuku-ku, Tokyo 162-8543, Japan (kuwanoy-tky@umin.ac.jp).

Accepted for Publication: November 11, 2008.

Author Contributions: Dr Kuwano had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Kuwano, Ishizaki, Watanabe, and Nanko. Acquisition of data: Kuwano, Ishizaki, Watanabe, and Nanko. Analysis and interpretation of data: Kuwano. Drafting of the manuscript: Kuwano and Watanabe. Critical revision of the manuscript for important intellectual content: Kuwano, Ishizaki, Watanabe, and Nanko. Statistical analysis: Kuwano. Administrative, technical, or material support: Kuwano and Ishizaki. Study supervision: Kuwano, Ishizaki, Watanabe, and Nanko.

Financial Disclosure: None reported.

This article was corrected online for typographical errors on 7/20/2009.

Schmid-Wendtner  MHBurgdorf  W Ultrasound scanning in dermatology. Arch Dermatol20051412217224
PubMed
Jovanovic  DLKatic  VJovanovic  B Value of preoperative determination of skin tumor thickness with 20-MHz ultrasound. Arch Dermatol20051412269270
PubMed
Fornage  BDMcGavran  MHDuvic  MWaldron  CA Imaging of the skin with 20-MHz US. Radiology199318916976
PubMed
Hoffmann  KGerbaulet  Uel-Gammal  SAltmeyer  P 20-MHz B-mode ultrasound in monitoring the course of localized scleroderma (morphea). Acta Derm Venereol Suppl (Stockh)1991164316
PubMed
Kreuter  AGambichler  TBreuckmann  F  et al Pulsed high-dose corticosteroids combined with low-dose methotrexate in severe localized scleroderma. Arch Dermatol20051417847852
PubMed
Ulrich  JVoit  C Ultrasound in dermatology, II: ultrasound of regional lymph node basins and subcutaneous tumours. Eur J Dermatol20011117379
PubMed
Schmid-Wendtner  MHPaerschke  GBaumert  JPlewig  GVolkenandt  M Value of ultrasonography compared with physical examination for the detection of locoregional metastases in patients with cutaneous melanoma. Melanoma Res2003132183188
PubMed
Blum  ASchlagenhauff  BStroebel  WBreuninger  HRassner  GGarbe  C Ultrasound examination of regional lymph nodes significantly improves early detection of locoregional metastases during the follow-up of patients with cutaneous melanoma: results of a prospective study of 1288 patients. Cancer2000881125342539
PubMed
Voit  CMayer  TKron  M  et al Efficacy of ultrasound B-scan compared with physical examination in follow-up of melanoma patients. Cancer2001911224092416
PubMed
Saiag  PBernard  MBeauchet  ABafounta  MLBourgault-Villada  IChagnon  S Ultrasonography using simple diagnostic criteria vs palpation for the detection of regional lymph node metastases of melanoma. Arch Dermatol20051412183189
PubMed
Fornage  BDTassin  GB Sonographic appearances of superficial soft tissue lipomas. J Clin Ultrasound1991194215220
PubMed
Ulrich  JGollnick  H Differential diagnosis of cutaneous and subcutaneous tumours assessed by 7.5 MHz ultrasonography. J Eur Acad Dermatol Venereol1999122187189
PubMed
Takemura  NFujii  NTanaka  T Epidermal cysts: the best surgical method can be determined by ultrasonographic imaging. Clin Exp Dermatol2007324445447
PubMed
Lee  HSJoo  KBSong  HT  et al Relationship between sonographic and pathologic findings in epidermal inclusion cysts. J Clin Ultrasound2001297374383
PubMed
Schäfer-Hesterberg  GSchoengen  ASterry  WVoit  C Use of ultrasound to early identify, diagnose and localize metastases in melanoma patients. Expert Rev Anticancer Ther200771217071716
PubMed
Wang  GJacobson  JAFeng  FYGirish  GCaoili  EMBrandon  C Sonography of wrist ganglion cysts: variable and noncystic appearances. J Ultrasound Med2007261013231328, quiz 1330-1331
PubMed
Inampudi  PJacobson  JAFessell  DP  et al Soft-tissue lipomas: accuracy of sonography in diagnosis with pathologic correlation. Radiology20042333763767
PubMed

Figures

Place holder to copy figure label and caption
Figure 1.

Typical ultrasonographic images of lipoma (A), epidermal cyst (B), and ganglion (C). A, An elongated isoechoic mass is evident in the subcutaneous tissue. There are striated echoes in the mass (arrow). B, A round to oval nonanechoic mass with a partial indentation to the dermis, dorsal acoustic amplification, and lateral shadows. C, An anechoic amorphous mass with a relatively sharp border and protrusion toward the joint (arrow). Arrowheads indicate masses.

Graphic Jump Location
Place holder to copy figure label and caption
Figure 2.

Sensitivity and specificity for the diagnosis of subcutaneous benign tumors. The sensitivity and the specificity for the diagnosis of lipoma, epidermal cyst, and ganglion were determined. The data are shown as percentages, and the error bars represent 95% confidence intervals. The asterisks indicate the significant difference between the sensitivity or the specificity after palpation and after ultrasonography (P < .05).

Graphic Jump Location

Tables

Table Graphic Jump LocationTable 1. Characteristics of 183 Patients With Subcutaneous Benign Lesions
Table Graphic Jump LocationTable 2. Comparison of Diagnostic Accuracy in the Examination of 183 Subcutaneous Benign Lesions
Table Graphic Jump LocationTable 3. Diagnostic Accuracy for Each Disease
Table Graphic Jump LocationTable 4. Positive and Negative Likelihood Ratios for the Diagnosis of Subcutaneous Benign Tumors

References

Schmid-Wendtner  MHBurgdorf  W Ultrasound scanning in dermatology. Arch Dermatol20051412217224
PubMed
Jovanovic  DLKatic  VJovanovic  B Value of preoperative determination of skin tumor thickness with 20-MHz ultrasound. Arch Dermatol20051412269270
PubMed
Fornage  BDMcGavran  MHDuvic  MWaldron  CA Imaging of the skin with 20-MHz US. Radiology199318916976
PubMed
Hoffmann  KGerbaulet  Uel-Gammal  SAltmeyer  P 20-MHz B-mode ultrasound in monitoring the course of localized scleroderma (morphea). Acta Derm Venereol Suppl (Stockh)1991164316
PubMed
Kreuter  AGambichler  TBreuckmann  F  et al Pulsed high-dose corticosteroids combined with low-dose methotrexate in severe localized scleroderma. Arch Dermatol20051417847852
PubMed
Ulrich  JVoit  C Ultrasound in dermatology, II: ultrasound of regional lymph node basins and subcutaneous tumours. Eur J Dermatol20011117379
PubMed
Schmid-Wendtner  MHPaerschke  GBaumert  JPlewig  GVolkenandt  M Value of ultrasonography compared with physical examination for the detection of locoregional metastases in patients with cutaneous melanoma. Melanoma Res2003132183188
PubMed
Blum  ASchlagenhauff  BStroebel  WBreuninger  HRassner  GGarbe  C Ultrasound examination of regional lymph nodes significantly improves early detection of locoregional metastases during the follow-up of patients with cutaneous melanoma: results of a prospective study of 1288 patients. Cancer2000881125342539
PubMed
Voit  CMayer  TKron  M  et al Efficacy of ultrasound B-scan compared with physical examination in follow-up of melanoma patients. Cancer2001911224092416
PubMed
Saiag  PBernard  MBeauchet  ABafounta  MLBourgault-Villada  IChagnon  S Ultrasonography using simple diagnostic criteria vs palpation for the detection of regional lymph node metastases of melanoma. Arch Dermatol20051412183189
PubMed
Fornage  BDTassin  GB Sonographic appearances of superficial soft tissue lipomas. J Clin Ultrasound1991194215220
PubMed
Ulrich  JGollnick  H Differential diagnosis of cutaneous and subcutaneous tumours assessed by 7.5 MHz ultrasonography. J Eur Acad Dermatol Venereol1999122187189
PubMed
Takemura  NFujii  NTanaka  T Epidermal cysts: the best surgical method can be determined by ultrasonographic imaging. Clin Exp Dermatol2007324445447
PubMed
Lee  HSJoo  KBSong  HT  et al Relationship between sonographic and pathologic findings in epidermal inclusion cysts. J Clin Ultrasound2001297374383
PubMed
Schäfer-Hesterberg  GSchoengen  ASterry  WVoit  C Use of ultrasound to early identify, diagnose and localize metastases in melanoma patients. Expert Rev Anticancer Ther200771217071716
PubMed
Wang  GJacobson  JAFeng  FYGirish  GCaoili  EMBrandon  C Sonography of wrist ganglion cysts: variable and noncystic appearances. J Ultrasound Med2007261013231328, quiz 1330-1331
PubMed
Inampudi  PJacobson  JAFessell  DP  et al Soft-tissue lipomas: accuracy of sonography in diagnosis with pathologic correlation. Radiology20042333763767
PubMed

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