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Slow-Growing Pediatric Neck Mass

Educational Objective
Based on this clinical scenario and the accompanying image, understand how to arrive at a correct diagnosis.
1 Credit CME

An 11-year-old girl with no significant medical history was referred to the pediatric otolaryngology department for a painless, left-sided neck mass that had been slowly enlarging for 8 months. On examination, there was an easily palpable 3-cm firm, fixed, well-circumscribed left supraclavicular mass without overlying skin changes or cutaneous involvement. She had no other masses, cervical lymphadenopathy, or systemic symptoms. In workup for this mass, she initially underwent ultrasound imaging, which demonstrated a hypoechoic mass. Findings from fine-needle aspiration and core-needle biopsy were inconclusive, demonstrating histiocytes. Magnetic resonance imaging demonstrated a well-circumscribed mass of mainly soft tissue density with contrast enhancement (Figure 1).

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C. Soft tissue aneurysmal bone cyst

The gross and microscopic findings were characteristic of a soft tissue (extraosseous) aneurysmal bone cyst (ABC) with USP6 locus rearrangement, confirming the diagnosis (Figure 2). Aneurysmal bone cysts are benign but locally aggressive tumors most commonly found in association with the long bones and spines of children and young adults.1,2 Extraosseous or soft tissue ABCs pathologically and genetically resemble those associated with bone but lack a bony attachment.2 Soft tissue ABCs are a rare phenomenon with approximately 40 cases reported in the literature.3 Extraosseous ABCs were first described in 1972 by Salm and Sissons as soft tissue lesions with identical histopathological findings as ABCs.4 Aneurysmal bone cysts are classically described as bony-shelled, blood-filled cysts with fibrous septa, which contain giant cells, woven bone, fibroblasts, and histiocytes.57 In 1999, Dal Cin et al described chromosomal rearrangement of 17p13 in all ABCs, including those associated only with soft tissue, confirming similar neoplastic pathogenesis.8 Furthermore, USP6 locus rearrangement has been determined to be sensitive for ABCs in a more recent study by Li et al.9 Magnetic resonance imaging is identical to osseous ABCs, demonstrating an expansile lesion, T2-weighted intense, with strong contrast enhancement and fluid levels.2,6,7,10 These lesions tend to occur within the first 2 decades of life, and of cases reported there is no sex predominance.2,10 Aneurysmal bone cysts, including the soft tissue variety, are difficult to diagnose given their rarity and similar presentation, clinically and radiographically, to other more common tumors such as giant cell tumors, extraskeletal osteosarcomas, ossifying fibromyxoid tumors, and myositis ossificans.2,3,6,7

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Article Information

Corresponding Author: Natalie Schauwecker, MD, Department of Otolaryngology–Head and Neck Surgery, Vanderbilt University Medical Center, 1215 21st Ave S, 7209 Medical Center East, South Tower, Nashville, TN 37232 (natalie.schauwecker@vumc.org).

Published Online: March 9, 2023. doi:10.1001/jamaoto.2023.0053

Conflict of Interest Disclosures: None reported.

Additional Contributions: We thank the patient’s mother for granting permission to publish this information.

Rosenberg  AE , Nielsen  GP , Fletcher  JA . Aneurysmal bone cyst. In: Fletcher  CDM , Bridge  JA , Hogendoorn  PCW , Mertens  F , eds.  WHO Classification of Tumours of Soft Tissue and Bone. IARC Press; 2013:348-349.
Hao  Y , Wang  L , Yan  M , Jin  F , Ge  S , Dai  K .  Soft tissue aneurysmal bone cyst in a 10-year-old girl.   Oncol Lett. 2012;3(3):545-548. doi:10.3892/ol.2011.530 PubMedGoogle ScholarCrossref
Song  W , Suurmeijer  AJH , Bollen  SM , Cleton-Jansen  AM , Bovée  JVMG , Kroon  HM .  Soft tissue aneurysmal bone cyst: six new cases with imaging details, molecular pathology, and review of the literature.   Skeletal Radiol. 2019;48(7):1059-1067. doi:10.1007/s00256-018-3135-x PubMedGoogle ScholarCrossref
Petrik  PK , Findlay  JM , Sherlock  RA .  Aneurysmal cyst, bone type, primary in an artery.   Am J Surg Pathol. 1993;17(10):1062-1066. doi:10.1097/00000478-199310000-00013PubMedGoogle ScholarCrossref
Nielsen  GP , Fletcher  CD , Smith  MA , Rybak  L , Rosenberg  AE .  Soft tissue aneurysmal bone cyst: a clinicopathologic study of five cases.   Am J Surg Pathol. 2002;26(1):64-69. doi:10.1097/00000478-200201000-00007PubMedGoogle ScholarCrossref
Baker  KS , Gould  ES , Patel  HB , Hwang  SJ .  Soft tissue aneurysmal bone cyst: a rare case in a middle aged patient.   J Radiol Case Rep. 2015;9(1):26-35. doi:10.3941/jrcr.v9i1.2157PubMedGoogle ScholarCrossref
Rodríguez-Peralto  JL , López-Barea  F , Sánchez-Herrera  S , Atienza  M .  Primary aneurysmal cyst of soft tissues (extraosseous aneurysmal cyst).   Am J Surg Pathol. 1994;18(6):632-636. doi:10.1097/00000478-199406000-00007PubMedGoogle Scholar
Dal Cin  P , Kozakewich  HP , Goumnerova  L , Mankin  HJ , Rosenberg  AE , Fletcher  JA .  Variant translocations involving 16q22 and 17p13 in solid variant and extraosseous forms of aneurysmal bone cyst.   Genes Chromosomes Cancer. 2000;28(2):233-234. doi:10.1002/(SICI)1098-2264(200006)28:2<233::AID-GCC13>3.0.CO;2-H PubMedGoogle Scholar
Li  L , Bui  MM , Zhang  M ,  et al.  Validation of fluorescence in situ hybridization testing of USP6 gene rearrangement for diagnosis of primary aneurysmal bone cyst.   Ann Clin Lab Sci. 2019;49(5):590-597.PubMedGoogle Scholar
Pietschmann  MF , Oliveira  AM , Chou  MM ,  et al.  Aneurysmal bone cysts of soft tissue represent true neoplasms: a report of two cases.   J Bone Joint Surg Am. 2011;93(9):e45. doi:10.2106/JBJS.J.00534PubMedGoogle Scholar
AMA CME Accreditation Information

Credit Designation Statement: The American Medical Association designates this Journal-based CME activity activity for a maximum of 1.00  AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to:

  • 1.00 Medical Knowledge MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program;;
  • 1.00 Self-Assessment points in the American Board of Otolaryngology – Head and Neck Surgery’s (ABOHNS) Continuing Certification program;
  • 1.00 MOC points in the American Board of Pediatrics’ (ABP) Maintenance of Certification (MOC) program;
  • 1.00 Lifelong Learning points in the American Board of Pathology’s (ABPath) Continuing Certification program; and
  • 1.00 CME points in the American Board of Surgery’s (ABS) Continuing Certification program

It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting MOC credit.

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