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 Table of Contents  
CASE REPORT
Year : 2019  |  Volume : 14  |  Issue : 3  |  Page : 261-264

Rhabdomyosarcoma of the forearm: USG, doppler, elastography, and magnetic resonance imaging with pathological correlation


Department of RadioDiagnosis, Jawaharlal Nehru Medical College, Wardha, Maharashtra, India

Date of Submission17-May-2019
Date of Decision06-Jun-2019
Date of Acceptance30-Jul-2019
Date of Web Publication2-May-2020

Correspondence Address:
Dr. Sakshi Daga
Department of RadioDiagnosis, Jawaharlal Nehru Medical College, Sawangi (Meghe), Wardha - 442 001, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdmimsu.jdmimsu_85_19

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  Abstract 


Rhabdomyosarcoma is a soft-tissue malignancy of skeletal muscle origin, with < 20% occurrence in extremities. We report the case of a 3-year-old boy who presented with a history of soft-tissue swelling over the anteromedial aspect of the left forearm. Radiological and histopathological findings were suggestive of rhabdomyosarcoma.

Keywords: Histopathological, malignancy, radiological, rhabdomyosarcoma


How to cite this article:
Daga S, Phatak S. Rhabdomyosarcoma of the forearm: USG, doppler, elastography, and magnetic resonance imaging with pathological correlation. J Datta Meghe Inst Med Sci Univ 2019;14:261-4

How to cite this URL:
Daga S, Phatak S. Rhabdomyosarcoma of the forearm: USG, doppler, elastography, and magnetic resonance imaging with pathological correlation. J Datta Meghe Inst Med Sci Univ [serial online] 2019 [cited 2020 Sep 28];14:261-4. Available from: http://www.journaldmims.com/text.asp?2019/14/3/261/283604




  Introduction Top


Soft-tissue sarcomas are the malignant pediatric neoplasms of mesenchymal origin classified into rhabdomyosarcomas and nonrhabdomyomatous soft-tissue sarcomas.[1] Rhabdomyosarcomas can occur anywhere in the body. The occurrence of such tumor in extremities is rare.[2] Radiological imaging plays an important role in the preoperative diagnosis of rhabdomyosarcoma as well as postoperative follow-up.[3]


  Case Report Top


A 3-year-old male child presented to the surgery outpatient department with a soft-tissue swelling over the left forearm. On history taking, his parents reported that swelling was presented for the past 6 months. Initially, the swelling was pea-sized with a gradual increase in size. The swelling was painless in nature. On examination, a nontender swelling of approximate size 8 cm × 5 cm was noticed on the left forearm, with no restriction of movements.

He was referred to the department of radiodiagnosis for further evaluation. Plain radiograph anteroposterior and lateral view of the forearm [Figure 1]a and [Figure 1]b showed a large soft-tissue swelling of size 8.5 cm × 4.5 cm over the medial aspect of the forearm, with no evidence of calcification and no erosions in the underlying bones. Grayscale ultrasound showed a well-demarcated soft-tissue mass lesion of size 7.8 cm × 5.5 cm over the anterior aspect of the left forearm, appearing heterogeneous predominantly hypoechogenic in echotexture. Few blood-fluid levels were noted within the normal limits [Figure 2]a and [Figure 2]b. [Figure 3] Color Doppler shows increased vascularity within. The mass appeared stiffer (predominantly blue color in center with green color at periphery) on sonoelastography with Tsukuba Elasticity Score (TES) of 4 and a strain ratio of 28 suggesting the possibility of malignancy [Figure 4].
Figure 1: (a) Lateral radiograph shows a large soft-tissue swelling of size 8.5 cm × 4.5 cm over the medial aspect of forearm with no evidence of calcification and no erosions in the underlying bones. (b) Anteroposterior radiograph shows a large soft-tissue swelling of size 8.5 cm × 4.5 cm over the medial aspect of forearm with no evidence of calcification and no erosions in the underlying bones

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Figure 2: (a and b) Grayscale USG showing well-demarcated heterogeneously hypoechoic soft-tissue mass lesion of size 7.8 cm × 5.5 cm in anteromedial aspect of forearm showing few blood fluid levels within

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Figure 3: Color Doppler reveals increased vascularity within the mass

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Figure 4: Sonoelastography reveals stiffer color (predominantly blue) suggestive solid nature of the mass with Tsukuba Elasticity Score of 4

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Magnetic resonance imaging (MRI) showed evidence of well-demarcated soft-tissue mass lesion of approximate size 8.3 cm × 4 cm × 3.8 cm in the anterior compartment of the left forearm appearing heterogeneously isointense to hypointense compared to surrounding muscles on T1-weighted image (T1WI) [Figure 6], heterogeneous on T2-weighted image (T2WI) [Figure 8], and hyperintense on Short tau inversion recovery (STIR) [Figure7] and PDFatSat [Figure 5]. Multiple hemorrhagic foci with blood fluid levels were noted within the mass. Postcontrast study [Figure 9] showed intense solid enhancement with multiple areas of cystic degeneration within.
Figure 5: Coronal PDFatsat magnetic resonance imaging image shows a well-demarcated soft-tissue mass lesion of approximate size 8.3 cm × 4 cm × 3.8 cm in the anterior compartment of the left forearm appearing hyperintense on PDFatSat

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Figure 6: Coronal T1-weighted image magnetic resonance imaging image shows well-demarcated soft-tissue mass lesion in the anterior compartment of the left forearm appearing heterogeneously isointense to hypointense compared to surrounding muscles on T1-weighted image

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Figure 7: Coronal STIR magnetic resonance imaging image shows well-demarcated soft-tissue mass lesion in the anterior compartment of the left forearm appearing hyperintense with characteristic blood-fluid levels

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Figure 8: Coronal T2-weighted image magnetic resonance imaging image shows well-demarcated soft-tissue mass lesion in the anterior compartment of the left forearm appearing heterogeneous on T2-weighted image with characteristic blood-fluid levels

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Figure 9: Coronal T1 = C (postcontrast) image shows intense solid enhancement of the lesion with multiple areas of cystic degeneration within

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Histopathology from the soft tissue revealed intramuscular stroma with sheets and nests of severely atypical round cells of mesenchymal origin, suggesting the features of rhabdomyosarcoma (embryonal type).


  Discussion Top


The incidence of malignant soft-tissue sarcoma in the pediatric age group is about 7%. The embryological origin of this tumor is from the primitive mesenchymal cells. They are categorized into two types: rhabdomyomatous and nonrhabdomyomatous soft-tissue sarcomas. Rhabdomyosarcomas account for nearly 50% of pediatric soft-tissue sarcomas.[4] These tumors are more common in children under the age group of 6 years, with slightly more male predilection.[5] They are divided into three types: embryonal, alveolar, and pleomorphic. Embryonal and alveolar subtypes are more common in the pediatric population; pleomorphic type is commonly seen in adult population.[6] The various sites of the occurrence of rhabdomyosarcoma include head and neck, genitourinary system, abdomen, and extremities. The patient may present with simple soft-tissue swelling without any other complaint. In some cases, swelling may be painful with associated body dysfunction.[7]

Imaging plays a prime role in determining the site, nature, and extent of soft-tissue sarcoma. Initial assessment begins with conventional radiography which reveals the presence of soft-tissue mass, pattern of soft-tissue calcification, associated periosteal reaction, cortical break though, and bone deformity.[8] Ultrasound is less invasive, easily available, and high-resolution screening modality to assess the extension of mass and its vascularity. A malignant soft-tissue sarcoma on ultrasound appears is large, ill-defined heterogeneous predominantly hypoechoic mass lesion with increased intrinsic vascularity within. Ultrasound proves beneficial in determining the soft tissue extension of malignant lesion. USG-guided biopsy can be taken to confirm the diagnosis.[7]

Sonoelastography is an evolving ultrasound modality that aids in assessing the elasticity of tissues. Elasticity can be evaluated using TES, also known as the Itoh-Score or Elasto-Score, which is a 5-point scoring system where Score 1 represents an even strain for entirely hypoechoic lesion (imparting an entire green color), Score 2 represents the strain in most of hypoechoic areas while some areas with no strain (a mixed pattern of green and blue color is visualized), Score 3 represents strain at the periphery of the lesion sparing its center (where periphery is imparted green color and center appears blue), Score 4 represents no strain in the entire hypoechoic lesion but sparing of its periphery (where center appears blue and periphery appears green), and a Score of 5 represents no strain in the entire hypoechoic lesion (imparting an entire blue color). Lesions Score 1 and 2 are considered benign, lesions with Score 3 are considered to be probably benign, and lesions with Score 4 and 5 are considered malignant.[9] Strain ratio is another parameter used for interpreting the elasticity of tissues. It is a semi-quantitative measurement useful for differentiating benign from malignant lesions. It is obtained by comparing a strain within the lesion with that of surrounding normal tissue of the same depth. Higher the strain ratio, higher will be the probability of malignancy.[10] In soft-tissue neoplasms, elastography helps to distinguish between benign and malignant nature. Malignant soft-tissue neoplasm appears hard or stiffer (predominantly blue color) on strain elastography.[11]

MRI is an investigation of choice for the diagnosis as well as posttreatment follow-up of soft-tissue sarcomas. It is superior to computed tomography in being able to delineate soft tissue changes well, no exposure to radiation, and less artifacts.[12] Rhabdomyosarcoma appears low-to-intermediate signal intensity compared to muscle on T1WI, higher signal intensity on T2WI, and STIR with heterogeneous enhancement on postcontrast study.[13]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Ryan CW, Meyer J, Maki R, Pollock RE, Savarese DM. Clinical presentation, histopathology, diagnostic evaluation, and staging of soft tissue sarcoma. Waltham, MA: Up To Date; 2012.  Back to cited text no. 1
    
2.
Laffan EE, Ngan BY, Navarro OM. Pediatric soft-tissue tumors and pseudotumors: MR imaging features with pathologic correlation: Part 2. Tumors of fibroblastic/myofibroblastic, so-called fibrohistiocytic, muscular, lymphomatous, neurogenic, hair matrix, and uncertain origin. Radiographics 2009;29:e36.  Back to cited text no. 2
    
3.
Landa J, Schwartz LH. Contemporary imaging in sarcoma. Oncologist 2009;14:1021-38.  Back to cited text no. 3
    
4.
Park K, van Rijn R, McHugh K. The role of radiology in paediatric soft tissue sarcomas. Cancer Imaging 2008;8:102-15.  Back to cited text no. 4
    
5.
Agarwala S. Pediatric rhabdomyosarcomas and nonrhabdomyosarcoma soft tissue sarcoma. J Indian Assoc Pediatr Surg 2006;11:15.  Back to cited text no. 5
  [Full text]  
6.
Nascimento AF. Rhabdomyosarcomas in adults: Classification and differential diagnosis. Diagn Histopathol 2008;14:538-45.  Back to cited text no. 6
    
7.
Morii T, Kishino T, Shimamori N, Motohashi M, Ohnishi H, Honya K, et al. Preoperative ultrasonographic evaluation for malignancy of soft-tissue sarcoma: A retrospective study. Open Orthop J 2018;12:75-83.  Back to cited text no. 7
    
8.
Manaster BJ. Soft-tissue masses: Optimal imaging protocol and reporting. AJR Am J Roentgenol 2013;201:505-14.  Back to cited text no. 8
    
9.
Itoh A, Ueno E, Tohno E, Kamma H, Takahashi H, Shiina T, et al. Breast disease: Clinical application of US elastography for diagnosis. Radiology 2006;239:341-50.  Back to cited text no. 9
    
10.
Carlsen JF, Ewertsen C, Lönn L, Nielsen MB. Strain Elastography Ultrasound: An Overview with Emphasis on Breast Cancer Diagnosis. Diagnostics (Basel) 2013;3:117-25.  Back to cited text no. 10
    
11.
Winn N, Lalam R, Cassar-Pullicino V. Sonoelastography in the musculoskeletal system: Current role and future directions. World J Radiol 2016;8:868-79.  Back to cited text no. 11
    
12.
Afonso PD, Mascarenhas VV. Imaging techniques for the diagnosis of soft tissue tumors. Rep Med Imaging 2015;8:63-70.  Back to cited text no. 12
    
13.
Saboo SS, Krajewski KM, Zukotynski K, Howard S, Jagannathan JP, Hornick JL, et al. Imaging features of primary and secondary adult rhabdomyosarcoma. AJR Am J Roentgenol 2012;199:W694-703.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]



 

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