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Embryonal rhabdomyosarcoma of the urachal ligament presenting as small bowel obstruction: Case report and review of the literature
Journal of Pediatric Surgery Case Reports 53 (2020) 101357
Contents lists available at ScienceDirect
Journal of Pediatric Surgery Case Reports
Embryonal rhabdomyosarcoma of the urachal ligament presenting as small bowel obstruction: Case report and review of the literature Imad Aljabban a, Christa N. Grant a, b, * a b
Pennsylvania State University College of Medicine, Hershey, PA, USA Penn State Health Milton S. Hershey Medical Center, Division of Pediatric Surgery, Hershey, PA, USA
ABSTRACT
Pediatric soft tissue sarcomas comprise a small proportion of pediatric solid malignancies and may arise in numerous anatomic locations such as the head and neck, trunk, extremities, and the genitourinary tract. Here, we present a case of rhabdomyosarcoma (RMS) arising from an unusual location, the urachus. The 3year-old patient initially presented with signs of small bowel obstruction. On diagnostic laparoscopy, an infraumbilical mass was discovered and removed by laparotomy. Analysis of the specimen confirmed embryonal RMS (ERMS). The patient was treated with a regimen of postoperative chemotherapy and radiation therapy. Although rare, prompt diagnostic evaluation and treatment of RMS may improve the long-term morbidity and mortality of these patients.
1. Background RMS is a malignant tumor arising from mesenchymal cells, and is the most common soft tissue sarcoma in children, making up 4.5% of all diagnosed childhood cancers [1]. RMS has a bimodal distribution with presentation between 2 to 6 and 10 to 18 years-old [2]. There are two subtypes, which include ERMS and alveolar RMS (ARMS). The former is more prevalent in younger populations and typically arises in the genitourinary system. ARMS is more likely to occur in older patients and predominantly involve the trunk and extremities. Histologically, both subtypes demonstrate positive immunostaining for desmin, myogenin, and MyoD1. Although the pathogenesis of RMS is poorly elucidated, it is suggested that mutations in macrophage inhibitory factor (MIF) and p53 are responsible for tumor progression [3,4]. ARMS can be differentiated from ERMS through genetic analysis by the presence of FOXO transcription factor gene fusion with either PAX3 or PAX7 transcription factor genes on chromosomes 2 and 1 respectively [5]. Tumors arising from the urachus are quite rare, and make up a small proportion of total genitourinary tumors. Pediatric urachal malignancies carry a poor prognosis, with only about 50%–60% 5-year survival. Only 9 other cases of ERMS derived from the urachus have been described in the literature; all were treated with a combination of surgery, chemotherapy, and radiotherapy (Table 1) [6]. Here, we present a case of our approach to a previously healthy child present-
*
ing with symptoms of bowel obstruction who was found to have a urachal ERMS. 2. Case report A 3-year-old male with a non-significant past medical history presented to the emergency department with 3 days of abdominal pain and constipation. Initial physical examination was significant for generalized abdominal tenderness with no rebound or guarding and hypoactive bowel sounds. ESR, CRP, and anion gap were elevated. Computed tomography (CT) of the abdomen demonstrated a partial small bowel obstruction with transition point in the lower abdomen, trace ascites in the right abdomen and question of intussusception at the transition point (Fig. 1). The differential diagnosis in this virgin abdomen included intraluminal or bowel wall lesions causing intussusception, and rare congenital lesions such as an omphalomesenteric duct remnant or ruptured Meckel's diverticulum. The patient was admitted to the pediatric surgery service and was taken for diagnostic laparoscopy. Once relaxed under general anesthesia, a partially mobile mass was palpable in the infraumbilical region. Diagnostic laparoscopy was performed. Upon entry into the peritoneal cavity, dilated loops of small bowel were discovered in the left upper quadrant. There was a conglomerate of bowel loops inferior to the umbilicus in the region of the palpated mass. The transition point was identified at the suprapubic area were small bowel loops were attached to the inflammatory
Corresponding author. Pennsylvania State University College of Medicine, Hershey, PA, USA. E-mail address: [email protected] (C.N. Grant).
https://doi.org/10.1016/j.epsc.2019.101357 Received 14 November 2019; Accepted 23 November 2019 Available online 28 November 2019 2213-5766/© 2019 The Authors. Published by (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Elsevier
Inc.
This
is
an
open
access
article
under
the
CC
BY-NC-ND
license
I. Aljabban and C.N. Grant
Journal of Pediatric Surgery Case Reports 53 (2020) 101357
Table 1
Characteristics of pediatric patients with urachal ligament embryonal rhabdomyosarcoma. Patient Author
Sex Age
Presentation
Location
Histology
Treatment
1
F
Abdominal mass
Urachus, adherent to the bladder
Embryonal
Surgical resection followed by chemotherapy
F
3yr 2m 3yr
Abdominal mass
Urachus
Embryonal
F
6yr 2yr 6m
Urachus, infiltrating the ventral abdominal wall, adherent to the dome of the bladder Urachus
Embryonal
F
Abdominal mass, constipation, nausea Abdominal mass, dysuria
Surgical resection, leaving marginal tumor residue, followed by chemotherapy Surgical resection followed by chemotherapy
2 3 4 5
Kerr et al. [6] Menke et al. [10] Fernandez et al. [11] Cheikhelard et al. [12]
Embryonal
Cheikhelard M et al. [12] Cheikhelard M et al. [12]
4yr 2m 5yr 3m
Abdominal mass, dysuria Abdominal mass
Urachus with peritoneal metastases
Embryonal
Urachus
Embryonal
7
Cheikhelard M et al. [12]
2yr 5m
Urachus with peritoneal and bone metastases
Embryonal
8
Cheikhelard M et al. [12] Cheikhelard M et al. [12]
4yr 5m 6yr
Abdominal mass, obstructive renal insufficiency Abdominal pain
Urachus
Embryonal
Abdominal pain
Urachus with peritoneal metastases
Embryonal
6
9
Microscopically incomplete resection followed by chemotherapy. Partial cystectomy. External abdominal radiotherapy Microscopically incomplete resection followed by chemotherapy. External abdominal radiotherapy Microscopically complete resection followed by chemotherapy. Small bowel resection. External abdominal radiotherapy Microscopically incomplete resection followed by chemotherapy. Partial cystectomy. External abdominal radiotherapy Microscopically complete resection followed by chemotherapy. Macroscopically complete resection followed by chemotherapy. External abdominal radiotherapy
Fig. 1. Computed Tomography Scan Abdomen and Pelvis on Initial Presentation. (A) Sagittal view reveals mass just posterior and inferior to umbilicus. Dotted arrows indicate transition point of bowel obstruction. On initial review, the mass was thought to be intussuscepted small bowel (B) Axial view again demonstrates the lesion which has the appearance of intussuscepted small bowel.
mass. Due to the densely adherent structures and poor visualization the operation was converted to a laparotomy. Once the abdominal wall was elevated, a deep red infraumbilical mass became apparent (Fig. 2). This mass was adherent to both the median umbilical ligaments; both were ligated and transected en bloc with the mass. The
mass was dissected circumferentially and resected completely. The bladder was brought to the into the field and the distal urachus was ligated. The proximal urachus was not identified, and given the location between the bladder dome and umbilicus, medial to both median umbilical ligaments, the mass was presumed to be originating from it.
Fig. 2. Resection of Urachal Mass. A: Hemostats mark urachal stump and bilateral median umbilical ligaments. Resected tumor is being held aloft to show the approximate prior relationship to these structures. B: local inflammation on mesentery of small bowel previously in contact with mass C: Resected mass. 2
I. Aljabban and C.N. Grant
Journal of Pediatric Surgery Case Reports 53 (2020) 101357
Of note, there was a small area of likely focal tumor necrosis, with semisolid grey-tan tissue attached to the abdominal wall and the small bowel serosa at the transition point of the bowel obstruction. The specimen measured 4.5 x 4.5 × 4.5 cm and was red-brown to pink with focal areas of hemorrhage and was partially encapsulated by a thin delicate membrane (Fig. 2). The patient did well post-operatively and was discharged from the hospital 5 days after initial presentation. Pathology and next generation sequencing confirmed the mass as an embryonal rhabdomyosarcoma with focal botryoid features, consistent with a urachal primary. The specimen was negative for FOX01, ALK, or FUS mutations. The patient underwent positron emission tomography (PET) scan and bone marrow biopsy, which showed no evidence of metastatic disease. While the tumor was completely removed and encapsulated on pathology, the semisolid material presumed to be necrotic tumor which remained adherent to the small bowel serosa led to a clinical stage of T2aN0M0, stage II, group 3. He was treated as intermediate risk due to possible residual disease. He was started on an alternating course of VAC (vincristine, dactinomycin, and cyclophosphamide) with VI (vincristine and irinotecan) and 36 Gy per 20 fraction of radiation therapy to the abdomen at 12 weeks. At the 5month follow-up visit, he was progressing well with no evidence of disease.
proach. The patient was noted to have an inflamed infraumbilical mass, which was resected and diagnosed pathologically using a combination of immunohistochemical staining and genetic analysis. Finally, chemotherapy and radiation therapy were used as part of his multimodality treatment strategy. Although ERMS is commonly confined to genitourinary tract, there is a possibility the tumor may arise along any site of mesenchymal origin. There is a need for new perspectives on early diagnosis and management of the unusually rare urachal ligament RMS. Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References [1] Dasgupta R, Rodeberg DA. Update on rhabdomyosarcoma. Semin Pediatr Surg 2012. https://doi.org/10.1053/j.sempedsurg.2011.10.007. [2] Miller RW, Young JL, Novakovic B. Childhood cancer. Cancer; 2000. [3] Tarnowski M, et al. Macrophage migration inhibitory factor is secreted by rhabdomyosarcoma cells, modulates tumor metastasis by binding to CXCR4 and CXCR7 receptors and inhibits recruitment of cancer-associated fibroblasts. Mol Cancer Res 2010. https://doi.org/10.1158/1541-7786.MCR-10-0288. [4] Xu J, et al. Targeting wild-type and mutant p53 with small molecule CP-31398 blocks the growth of rhabdomyosarcoma by inducing reactive oxygen speciesdependent apoptosis. Cancer Res 2010. https://doi.org/10.1158/0008-5472.CAN10-0942. [5] Sorensen PHB, et al. PAX3-FKHR and PAX7-FKHR gene fusions are prognostic indicators in alveolar rhabdomyosarcoma: a report from the Children’s Oncology Group. J Clin Oncol 2002. https://doi.org/10.1200/JCO.2002.03.137. [6] Sánchez-Montenegro C, et al. Costello syndrome and umbilical ligament rhabdomyosarcoma in two pediatric patients: case reports and review of the literature. Case Rep. Genet. 2017. https://doi.org/10.1155/2017/1587610. [7] Dantonello TM, et al. Embryonal rhabdomyosarcoma with metastases confined to the lungs: report from the CWS Study Group. Pediatr Blood Cancer 2011. https:// doi.org/10.1002/pbc.22862. [8] Arndt CAS, et al. Vincristine, actinomycin, and cyclophosphamide compared with vincristine, actinomycin, and cyclophosphamide alternating with vincristine, topotecan, and cyclophosphamide for intermediate-risk rhabdomyosarcoma: children’s Oncology Group Study D9803. J Clin Oncol 2009. https://doi.org/10. 1200/JCO.2009.22.3768. [9] Wharam MD, et al. Radiation therapy for rhabdomyosarcoma: local failure risk for clinical group III patients on intergroup rhabdomyosarcoma study II. Int J Radiat Oncol Biol Phys 1997. https://doi.org/10.1016/S0360-3016(97)00120-X. [10] Menke J, et al. Uniparental trisomy of a mutated HRAS proto-oncogene in embryonal rhabdomyosarcoma of a patient with Costello syndrome. J Clin Oncol 2015. https://doi.org/10.1200/JCO.2013.49.6539. [11] Fernández EMLT, et al. Radical surgery and IVA-chemotherapeutic regimen to treat embryonal rhabdomyosarcoma of the urachus: case report. Pediatr Hematol Oncol 2007. https://doi.org/10.1080/08880010701533678. [12] Cheikhelard A, et al. Urachal rhabdomyosarcoma in childhood: a rare entity with a poor outcome. J Pediatr Surg 2015. https://doi.org/10.1016/j.jpedsurg.2014.12. 023.
3. Discussion Urachal ligament tumors are very rare, and may be diagnosed late due to tumor expansion into the peritoneum with few symptoms. Patients who are suspected to have intra-abdominal RMS should undergo cross-sectional imaging with CT or magnetic resonance imaging (MRI) to identify the primary tumor. Identification of metastasis to lymph nodes or distant sites, most commonly the lungs is crucial [7]. Lymph nodes identified as larger than 1 cm on imaging studies should be considered for biopsy. If resectable on diagnosis, surgical resection of the tumor with 0.5 cm margins is the recommended initial therapy for RMS. Chemotherapy is recommended in all low and intermediate risk RMS patients. Children's Oncology Group (COG) studies use VAC as standard therapy. VI is added in intermediate risk groups; while this has not shown improved outcomes compared to standard VAC therapy, lower hematologic toxicity has been demonstrated [8]. Additionally, radiation therapy, given to all groups except group 1, has been shown to improve patient mortality with variable outcomes depending on the amount of residual tumor tissue remaining after surgical resection [9]. 4. Conclusion This case demonstrates the successful treatment of a rare ERMS tumor arising in the urachus of a child using an interdisciplinary ap-
3
Contents lists available at ScienceDirect
Journal of Pediatric Surgery Case Reports
Embryonal rhabdomyosarcoma of the urachal ligament presenting as small bowel obstruction: Case report and review of the literature Imad Aljabban a, Christa N. Grant a, b, * a b
Pennsylvania State University College of Medicine, Hershey, PA, USA Penn State Health Milton S. Hershey Medical Center, Division of Pediatric Surgery, Hershey, PA, USA
ABSTRACT
Pediatric soft tissue sarcomas comprise a small proportion of pediatric solid malignancies and may arise in numerous anatomic locations such as the head and neck, trunk, extremities, and the genitourinary tract. Here, we present a case of rhabdomyosarcoma (RMS) arising from an unusual location, the urachus. The 3year-old patient initially presented with signs of small bowel obstruction. On diagnostic laparoscopy, an infraumbilical mass was discovered and removed by laparotomy. Analysis of the specimen confirmed embryonal RMS (ERMS). The patient was treated with a regimen of postoperative chemotherapy and radiation therapy. Although rare, prompt diagnostic evaluation and treatment of RMS may improve the long-term morbidity and mortality of these patients.
1. Background RMS is a malignant tumor arising from mesenchymal cells, and is the most common soft tissue sarcoma in children, making up 4.5% of all diagnosed childhood cancers [1]. RMS has a bimodal distribution with presentation between 2 to 6 and 10 to 18 years-old [2]. There are two subtypes, which include ERMS and alveolar RMS (ARMS). The former is more prevalent in younger populations and typically arises in the genitourinary system. ARMS is more likely to occur in older patients and predominantly involve the trunk and extremities. Histologically, both subtypes demonstrate positive immunostaining for desmin, myogenin, and MyoD1. Although the pathogenesis of RMS is poorly elucidated, it is suggested that mutations in macrophage inhibitory factor (MIF) and p53 are responsible for tumor progression [3,4]. ARMS can be differentiated from ERMS through genetic analysis by the presence of FOXO transcription factor gene fusion with either PAX3 or PAX7 transcription factor genes on chromosomes 2 and 1 respectively [5]. Tumors arising from the urachus are quite rare, and make up a small proportion of total genitourinary tumors. Pediatric urachal malignancies carry a poor prognosis, with only about 50%–60% 5-year survival. Only 9 other cases of ERMS derived from the urachus have been described in the literature; all were treated with a combination of surgery, chemotherapy, and radiotherapy (Table 1) [6]. Here, we present a case of our approach to a previously healthy child present-
*
ing with symptoms of bowel obstruction who was found to have a urachal ERMS. 2. Case report A 3-year-old male with a non-significant past medical history presented to the emergency department with 3 days of abdominal pain and constipation. Initial physical examination was significant for generalized abdominal tenderness with no rebound or guarding and hypoactive bowel sounds. ESR, CRP, and anion gap were elevated. Computed tomography (CT) of the abdomen demonstrated a partial small bowel obstruction with transition point in the lower abdomen, trace ascites in the right abdomen and question of intussusception at the transition point (Fig. 1). The differential diagnosis in this virgin abdomen included intraluminal or bowel wall lesions causing intussusception, and rare congenital lesions such as an omphalomesenteric duct remnant or ruptured Meckel's diverticulum. The patient was admitted to the pediatric surgery service and was taken for diagnostic laparoscopy. Once relaxed under general anesthesia, a partially mobile mass was palpable in the infraumbilical region. Diagnostic laparoscopy was performed. Upon entry into the peritoneal cavity, dilated loops of small bowel were discovered in the left upper quadrant. There was a conglomerate of bowel loops inferior to the umbilicus in the region of the palpated mass. The transition point was identified at the suprapubic area were small bowel loops were attached to the inflammatory
Corresponding author. Pennsylvania State University College of Medicine, Hershey, PA, USA. E-mail address: [email protected] (C.N. Grant).
https://doi.org/10.1016/j.epsc.2019.101357 Received 14 November 2019; Accepted 23 November 2019 Available online 28 November 2019 2213-5766/© 2019 The Authors. Published by (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Elsevier
Inc.
This
is
an
open
access
article
under
the
CC
BY-NC-ND
license
I. Aljabban and C.N. Grant
Journal of Pediatric Surgery Case Reports 53 (2020) 101357
Table 1
Characteristics of pediatric patients with urachal ligament embryonal rhabdomyosarcoma. Patient Author
Sex Age
Presentation
Location
Histology
Treatment
1
F
Abdominal mass
Urachus, adherent to the bladder
Embryonal
Surgical resection followed by chemotherapy
F
3yr 2m 3yr
Abdominal mass
Urachus
Embryonal
F
6yr 2yr 6m
Urachus, infiltrating the ventral abdominal wall, adherent to the dome of the bladder Urachus
Embryonal
F
Abdominal mass, constipation, nausea Abdominal mass, dysuria
Surgical resection, leaving marginal tumor residue, followed by chemotherapy Surgical resection followed by chemotherapy
2 3 4 5
Kerr et al. [6] Menke et al. [10] Fernandez et al. [11] Cheikhelard et al. [12]
Embryonal
Cheikhelard M et al. [12] Cheikhelard M et al. [12]
4yr 2m 5yr 3m
Abdominal mass, dysuria Abdominal mass
Urachus with peritoneal metastases
Embryonal
Urachus
Embryonal
7
Cheikhelard M et al. [12]
2yr 5m
Urachus with peritoneal and bone metastases
Embryonal
8
Cheikhelard M et al. [12] Cheikhelard M et al. [12]
4yr 5m 6yr
Abdominal mass, obstructive renal insufficiency Abdominal pain
Urachus
Embryonal
Abdominal pain
Urachus with peritoneal metastases
Embryonal
6
9
Microscopically incomplete resection followed by chemotherapy. Partial cystectomy. External abdominal radiotherapy Microscopically incomplete resection followed by chemotherapy. External abdominal radiotherapy Microscopically complete resection followed by chemotherapy. Small bowel resection. External abdominal radiotherapy Microscopically incomplete resection followed by chemotherapy. Partial cystectomy. External abdominal radiotherapy Microscopically complete resection followed by chemotherapy. Macroscopically complete resection followed by chemotherapy. External abdominal radiotherapy
Fig. 1. Computed Tomography Scan Abdomen and Pelvis on Initial Presentation. (A) Sagittal view reveals mass just posterior and inferior to umbilicus. Dotted arrows indicate transition point of bowel obstruction. On initial review, the mass was thought to be intussuscepted small bowel (B) Axial view again demonstrates the lesion which has the appearance of intussuscepted small bowel.
mass. Due to the densely adherent structures and poor visualization the operation was converted to a laparotomy. Once the abdominal wall was elevated, a deep red infraumbilical mass became apparent (Fig. 2). This mass was adherent to both the median umbilical ligaments; both were ligated and transected en bloc with the mass. The
mass was dissected circumferentially and resected completely. The bladder was brought to the into the field and the distal urachus was ligated. The proximal urachus was not identified, and given the location between the bladder dome and umbilicus, medial to both median umbilical ligaments, the mass was presumed to be originating from it.
Fig. 2. Resection of Urachal Mass. A: Hemostats mark urachal stump and bilateral median umbilical ligaments. Resected tumor is being held aloft to show the approximate prior relationship to these structures. B: local inflammation on mesentery of small bowel previously in contact with mass C: Resected mass. 2
I. Aljabban and C.N. Grant
Journal of Pediatric Surgery Case Reports 53 (2020) 101357
Of note, there was a small area of likely focal tumor necrosis, with semisolid grey-tan tissue attached to the abdominal wall and the small bowel serosa at the transition point of the bowel obstruction. The specimen measured 4.5 x 4.5 × 4.5 cm and was red-brown to pink with focal areas of hemorrhage and was partially encapsulated by a thin delicate membrane (Fig. 2). The patient did well post-operatively and was discharged from the hospital 5 days after initial presentation. Pathology and next generation sequencing confirmed the mass as an embryonal rhabdomyosarcoma with focal botryoid features, consistent with a urachal primary. The specimen was negative for FOX01, ALK, or FUS mutations. The patient underwent positron emission tomography (PET) scan and bone marrow biopsy, which showed no evidence of metastatic disease. While the tumor was completely removed and encapsulated on pathology, the semisolid material presumed to be necrotic tumor which remained adherent to the small bowel serosa led to a clinical stage of T2aN0M0, stage II, group 3. He was treated as intermediate risk due to possible residual disease. He was started on an alternating course of VAC (vincristine, dactinomycin, and cyclophosphamide) with VI (vincristine and irinotecan) and 36 Gy per 20 fraction of radiation therapy to the abdomen at 12 weeks. At the 5month follow-up visit, he was progressing well with no evidence of disease.
proach. The patient was noted to have an inflamed infraumbilical mass, which was resected and diagnosed pathologically using a combination of immunohistochemical staining and genetic analysis. Finally, chemotherapy and radiation therapy were used as part of his multimodality treatment strategy. Although ERMS is commonly confined to genitourinary tract, there is a possibility the tumor may arise along any site of mesenchymal origin. There is a need for new perspectives on early diagnosis and management of the unusually rare urachal ligament RMS. Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References [1] Dasgupta R, Rodeberg DA. Update on rhabdomyosarcoma. Semin Pediatr Surg 2012. https://doi.org/10.1053/j.sempedsurg.2011.10.007. [2] Miller RW, Young JL, Novakovic B. Childhood cancer. Cancer; 2000. [3] Tarnowski M, et al. Macrophage migration inhibitory factor is secreted by rhabdomyosarcoma cells, modulates tumor metastasis by binding to CXCR4 and CXCR7 receptors and inhibits recruitment of cancer-associated fibroblasts. Mol Cancer Res 2010. https://doi.org/10.1158/1541-7786.MCR-10-0288. [4] Xu J, et al. Targeting wild-type and mutant p53 with small molecule CP-31398 blocks the growth of rhabdomyosarcoma by inducing reactive oxygen speciesdependent apoptosis. Cancer Res 2010. https://doi.org/10.1158/0008-5472.CAN10-0942. [5] Sorensen PHB, et al. PAX3-FKHR and PAX7-FKHR gene fusions are prognostic indicators in alveolar rhabdomyosarcoma: a report from the Children’s Oncology Group. J Clin Oncol 2002. https://doi.org/10.1200/JCO.2002.03.137. [6] Sánchez-Montenegro C, et al. Costello syndrome and umbilical ligament rhabdomyosarcoma in two pediatric patients: case reports and review of the literature. Case Rep. Genet. 2017. https://doi.org/10.1155/2017/1587610. [7] Dantonello TM, et al. Embryonal rhabdomyosarcoma with metastases confined to the lungs: report from the CWS Study Group. Pediatr Blood Cancer 2011. https:// doi.org/10.1002/pbc.22862. [8] Arndt CAS, et al. Vincristine, actinomycin, and cyclophosphamide compared with vincristine, actinomycin, and cyclophosphamide alternating with vincristine, topotecan, and cyclophosphamide for intermediate-risk rhabdomyosarcoma: children’s Oncology Group Study D9803. J Clin Oncol 2009. https://doi.org/10. 1200/JCO.2009.22.3768. [9] Wharam MD, et al. Radiation therapy for rhabdomyosarcoma: local failure risk for clinical group III patients on intergroup rhabdomyosarcoma study II. Int J Radiat Oncol Biol Phys 1997. https://doi.org/10.1016/S0360-3016(97)00120-X. [10] Menke J, et al. Uniparental trisomy of a mutated HRAS proto-oncogene in embryonal rhabdomyosarcoma of a patient with Costello syndrome. J Clin Oncol 2015. https://doi.org/10.1200/JCO.2013.49.6539. [11] Fernández EMLT, et al. Radical surgery and IVA-chemotherapeutic regimen to treat embryonal rhabdomyosarcoma of the urachus: case report. Pediatr Hematol Oncol 2007. https://doi.org/10.1080/08880010701533678. [12] Cheikhelard A, et al. Urachal rhabdomyosarcoma in childhood: a rare entity with a poor outcome. J Pediatr Surg 2015. https://doi.org/10.1016/j.jpedsurg.2014.12. 023.
3. Discussion Urachal ligament tumors are very rare, and may be diagnosed late due to tumor expansion into the peritoneum with few symptoms. Patients who are suspected to have intra-abdominal RMS should undergo cross-sectional imaging with CT or magnetic resonance imaging (MRI) to identify the primary tumor. Identification of metastasis to lymph nodes or distant sites, most commonly the lungs is crucial [7]. Lymph nodes identified as larger than 1 cm on imaging studies should be considered for biopsy. If resectable on diagnosis, surgical resection of the tumor with 0.5 cm margins is the recommended initial therapy for RMS. Chemotherapy is recommended in all low and intermediate risk RMS patients. Children's Oncology Group (COG) studies use VAC as standard therapy. VI is added in intermediate risk groups; while this has not shown improved outcomes compared to standard VAC therapy, lower hematologic toxicity has been demonstrated [8]. Additionally, radiation therapy, given to all groups except group 1, has been shown to improve patient mortality with variable outcomes depending on the amount of residual tumor tissue remaining after surgical resection [9]. 4. Conclusion This case demonstrates the successful treatment of a rare ERMS tumor arising in the urachus of a child using an interdisciplinary ap-
3