Answer: A
Bone tumors are typically categorized as aggressive versus non-aggressive (including neoplastic, infectious, metabolic, and other etiologies). In deciding which main category applies, radiologists make note of the presence or absence of sharp demarcating lines, sclerosis, and disruption of other landmarks (to name a few considerations). For patients under 20 years of age, examples of aggressive tumors are osteosarcoma, Ewing sarcoma, osteomyelitis, and metastases. Non-aggressive tumors can be lytic (aneurysmal bone cysts, unicameral bone cysts, among others) or blastic (osteoid osteoma, osteochondroma, among others).
Aggressive tumors typically require aggressive intervention; non-aggressive tumors may or may not.
The truth is: the differential diagnosis of bony tumors in children and adults is extensive, and impractical for emergency physicians to commit to memory. However, there are a few relatively more common benign tumors that can be identified by history, physical examination, and plain radiographs.
This boy presents with an osteoid osteoma (A) (aka osteoblastoma) a benign bone tumor of childhood with
predilection for the long bones. Typically diagnosed before the 2nd decade, patients may complain of
subacute bony pain – especially at night – that is readily treated well with NSAIDs. On plain films, there is a lucent nidus surrounded by reactive cortical thickening (this boy’s films have a classic appearance). If this
classic finding is unclear on xray, CT may be needed to verify the lucent nidus (and perhaps may reveal a central calcium dot). Osteoid osteomas typically do not progress and will often resolve over the course of years.
Medical management is the mainstay; rarely do these need surgical intervention.
Osteochondroma (B) is the most common benign tumor in children and adolescents, also usually involving the long bones. The typical patient is between 5 and 15 years of age and presents with a non-painful,
firm, discrete mass (or this may be a radiographically incidental finding). Radiographs may reveal a
sessile or pedunculated mass, usually projected away from the joint:
Bone tumors are typically categorized as aggressive versus non-aggressive (including neoplastic, infectious, metabolic, and other etiologies). In deciding which main category applies, radiologists make note of the presence or absence of sharp demarcating lines, sclerosis, and disruption of other landmarks (to name a few considerations). For patients under 20 years of age, examples of aggressive tumors are osteosarcoma, Ewing sarcoma, osteomyelitis, and metastases. Non-aggressive tumors can be lytic (aneurysmal bone cysts, unicameral bone cysts, among others) or blastic (osteoid osteoma, osteochondroma, among others).
Aggressive tumors typically require aggressive intervention; non-aggressive tumors may or may not.
The truth is: the differential diagnosis of bony tumors in children and adults is extensive, and impractical for emergency physicians to commit to memory. However, there are a few relatively more common benign tumors that can be identified by history, physical examination, and plain radiographs.
This boy presents with an osteoid osteoma (A) (aka osteoblastoma) a benign bone tumor of childhood with
predilection for the long bones. Typically diagnosed before the 2nd decade, patients may complain of
subacute bony pain – especially at night – that is readily treated well with NSAIDs. On plain films, there is a lucent nidus surrounded by reactive cortical thickening (this boy’s films have a classic appearance). If this
classic finding is unclear on xray, CT may be needed to verify the lucent nidus (and perhaps may reveal a central calcium dot). Osteoid osteomas typically do not progress and will often resolve over the course of years.
Medical management is the mainstay; rarely do these need surgical intervention.
Osteochondroma (B) is the most common benign tumor in children and adolescents, also usually involving the long bones. The typical patient is between 5 and 15 years of age and presents with a non-painful,
firm, discrete mass (or this may be a radiographically incidental finding). Radiographs may reveal a
sessile or pedunculated mass, usually projected away from the joint:
These are mostly benign lesions (unless associated with a rare syndrome of multiple exostoses); resection is warranted if the osteochondroma threatens growth, vascular flow, or for cosmetic reasons.
Unicameral bone cysts are fluid-containing defects of flat and tubular bones. The typical patient is a pre-pubescent child; presentations are even divided evenly: asymptomatic/incidental (50%) and associated with a pathologic fracture (50%), due to the compromised biomechanical integrity of the long bone. The “fallen leaf” sign is pathognomonic for a piece of cortex that has broken off and fallen into the cystic chamber. The main goal of management is to attain a functionally stable bone, usually through excision or steroid injection of the cyst.
Unicameral bone cysts are fluid-containing defects of flat and tubular bones. The typical patient is a pre-pubescent child; presentations are even divided evenly: asymptomatic/incidental (50%) and associated with a pathologic fracture (50%), due to the compromised biomechanical integrity of the long bone. The “fallen leaf” sign is pathognomonic for a piece of cortex that has broken off and fallen into the cystic chamber. The main goal of management is to attain a functionally stable bone, usually through excision or steroid injection of the cyst.
An aneurysmal bone cyst is a rare, rapidly expanding, and destructive lesion that typically presents before the early twenties with a painful mass and possibly a pathologic fracture. On plain films, there is an appearance of “soapy bubbles” (in distinction from the mostly homogeneous unicameral cyst) and may show blood-air levels:
Although not cancerous, these tumors are aggressive, lytic lesions that require intervention: curettage and bone grafts with or without low-dose radiation treatment. Recurrence is common, especially in younger patients, and those within 2 years of prior treatment.
Summary
The differential diagnosis of bone tumors depends on age of the patient and appearance on plain films.
Clearly benign lesions by clinical assessment and plain films may be observed. CT may be helpful in cases where defining the bony anatomy is inconclusive. For aggressive tumors, non-apparent cases, or where soft-tissue characterization is essential, MR is recommended. The above non-malignant tumors are typically diagnosed by history, physical examination, and plain radiography.
Summary
The differential diagnosis of bone tumors depends on age of the patient and appearance on plain films.
Clearly benign lesions by clinical assessment and plain films may be observed. CT may be helpful in cases where defining the bony anatomy is inconclusive. For aggressive tumors, non-apparent cases, or where soft-tissue characterization is essential, MR is recommended. The above non-malignant tumors are typically diagnosed by history, physical examination, and plain radiography.
References
Johnston JO. “Bone cysts”. www.tumorlibrary.com. 2013.
Jones J. “Osteoid Osteoma.” www.radiopaedia.org. 2013.
McQuillen KK. “Nonmalignant Tumors of Bone” In: Strange GR, Ahrens WA, Schafermeyer RW (eds). Pediatric Emergency Medicine. 2nd Ed. McGraw-Hill. New York. 2012.
Schreibman KL. Lecture: “Bone Tumors”. Department of Radiology, University of Wisconsin—Madison. 2013.
University of Washington, Department of Radiology. Teaching Materials: Lucent Lesions of Bone. www.rad.washington.edu. 2013.
Wheeless CR. Wheeless Online: www.wheelessonline.com.
Special thanks to Dr Marianne Gausche-Hill for inspiring the bonus track!
Johnston JO. “Bone cysts”. www.tumorlibrary.com. 2013.
Jones J. “Osteoid Osteoma.” www.radiopaedia.org. 2013.
McQuillen KK. “Nonmalignant Tumors of Bone” In: Strange GR, Ahrens WA, Schafermeyer RW (eds). Pediatric Emergency Medicine. 2nd Ed. McGraw-Hill. New York. 2012.
Schreibman KL. Lecture: “Bone Tumors”. Department of Radiology, University of Wisconsin—Madison. 2013.
University of Washington, Department of Radiology. Teaching Materials: Lucent Lesions of Bone. www.rad.washington.edu. 2013.
Wheeless CR. Wheeless Online: www.wheelessonline.com.
Special thanks to Dr Marianne Gausche-Hill for inspiring the bonus track!