**3.4 Tumor mimickers**

1.**Brodie Abscess:** Brodie Abscess is an intraosseous abscess associated with subacute pyogenic osteomyelitis and can often be confused as a bone tumor. There is typically an insidious onset with systemic inflammatory signs, and symptoms are often absent [82]. *Staphylococcus aureus* is the most common organism involved. It typically occurs in the metaphysis of long bones, with proximal and distal tibial metaphyses are most commonly involved. On radiography/CT, Brodie abscess is typically a metaphyseal radiolucent lesion with a sclerotic rim along the long axis of the bone (**Figure 25A**). If a lucent

**Figure 25.**

**Figure 26.**

**47**

*Brodie Abscess: Frontal radiograph of the left knee (A) shows a lucent area (white arrow) with a faintly sclerotic peripheral rim in the proximal tibial epi-metaphyseal region. B demonstrates the "Penumbra sign" with rim lining of the abscess cavity (white arrow) with higher signal intensity than that of the remaining abscess on T1-weighted imaging. The abscess shows increased T2 signal (white arrows; C-D) and peripheral*

*Brown tumor: Frontal radiograph of the left knee (A) shows an eccentric, well-defined, lytic lesion (white arrow) in the proximal tibial epi-metaphyseal region with associated thinning and expansion of cortex. Similar appearing lytic areas (white arrows) are identified in the distal radius (B), pelvic bones and proximal right femur (C), and distal radius and ulna and proximal fifth metacarpal (D). Color flow ultrasound image of the neck (E) demonstrates a well-defined hypoechoic solid parathyroid mass (yellow arrow). The parathyroid mass*

*rim enhancement (white arrows) on the postcontrast images (E-F).*

*Imaging of Pediatric Benign Bone Tumors DOI: http://dx.doi.org/10.5772/intechopen.99021*

*appears as a hot spot (yellow arrow) on nuclear imaging scan (F).*

#### **Figure 24.**

*Intraosseous hemangioma: Sagittal MR images of lumbar spine reveal a focal well-circumscribed signal abnormality in the vertebral body (white arrows) that is hyperintense on both T2-weighted (A) and T1-weighted (B) images represent a small vertebral hemangioma.*

#### **Figure 25.**

**3.3 Vascular lesions**

*3.3.1 Intraosseous hemangioma*

*Recent Advances in Bone Tumours and Osteoarthritis*

managed by radiotherapy [81].

**3.4 Tumor mimickers**

**Figure 24.**

**46**

Intraosseous hemangioma (IH) is a benign, slow-growing vascular neoplasm. Though it mainly involves the vertebrae and craniofacial bones, it can rarely involve long bones (mainly intramedullary in metadiaphyseal region; rarely cortical or subperiosteal) [79]. IH are usually identified in females between the age of 30– 50 years. The most common pathologic type is cavernous hemangioma. On radiographs, intraosseous hemangiomas may show a "sunburst" or "honeycomb" appearance. On CT, IH may demonstrate the classic "polka dot" sign (due to associated coarse appearance of the trabecular bone), honeycomb appearance of the lytic lesion (because of internal linear trabeculations), or a spiculated "Irish lace" pattern. MRI helps in better delineation of location and extent of the hemangioma. On MRI, IH demonstrates intermediate to high T1 signal, high T2 signal, and diffuse or peripheral enhancement with signal intensity similar to the adjacent vessels [80] (**Figure 24A** and **B**). Most of the IH lesions are asymptomatic and need no treatment. Symptomatic vertebral hemangiomas without neurologic deficits can be

1.**Brodie Abscess:** Brodie Abscess is an intraosseous abscess associated with subacute pyogenic osteomyelitis and can often be confused as a bone tumor. There is typically an insidious onset with systemic inflammatory signs, and symptoms are often absent [82]. *Staphylococcus aureus* is the most common organism involved. It typically occurs in the metaphysis of long bones, with proximal and distal tibial metaphyses are most commonly involved. On radiography/CT, Brodie abscess is typically a metaphyseal radiolucent lesion with a sclerotic rim along the long axis of the bone (**Figure 25A**). If a lucent

*Intraosseous hemangioma: Sagittal MR images of lumbar spine reveal a focal well-circumscribed signal abnormality in the vertebral body (white arrows) that is hyperintense on both T2-weighted (A) and*

*T1-weighted (B) images represent a small vertebral hemangioma.*

*Brodie Abscess: Frontal radiograph of the left knee (A) shows a lucent area (white arrow) with a faintly sclerotic peripheral rim in the proximal tibial epi-metaphyseal region. B demonstrates the "Penumbra sign" with rim lining of the abscess cavity (white arrow) with higher signal intensity than that of the remaining abscess on T1-weighted imaging. The abscess shows increased T2 signal (white arrows; C-D) and peripheral rim enhancement (white arrows) on the postcontrast images (E-F).*

#### **Figure 26.**

*Brown tumor: Frontal radiograph of the left knee (A) shows an eccentric, well-defined, lytic lesion (white arrow) in the proximal tibial epi-metaphyseal region with associated thinning and expansion of cortex. Similar appearing lytic areas (white arrows) are identified in the distal radius (B), pelvic bones and proximal right femur (C), and distal radius and ulna and proximal fifth metacarpal (D). Color flow ultrasound image of the neck (E) demonstrates a well-defined hypoechoic solid parathyroid mass (yellow arrow). The parathyroid mass appears as a hot spot (yellow arrow) on nuclear imaging scan (F).*

tract extends to physis, diagnosis of Brodie abscess is strongly suggested. There may be associated periosteal reaction. On MRI, there is a T1 hypointense center with T1 hyperintense rim due to peripheral vascularized granulation tissue lining the abscess cavity, which is also termed as "MR penumbra sign" [83] (**Figure 25B**–**E**). There is typical rim enhancement following contrast administration (**Figure 25F**). Brodie abscess is usually treated with surgical curettage and antibiotic therapy [82].

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2.**Brown Tumor/Osteitis Fibrosa Cystica:** Brown tumor, also known as osteitis fibrosa cystica is the skeletal manifestation of hyperparathyroidism, most commonly related to parathyroid adenoma. Parathormone induces osteoclastic activity, which results in multifocal bone cyst formation and osteopenia. The name brown tumor is derived from color resulting from hemosiderin deposition. Brown tumor is rare, seen in less than 3% of cases of hyperparathyroidism [84]. On radiography/CT, these lesions are typically multifocal well-defined radiolucent lesions with expansion and thinning of the overlying cortex (**Figure 26A**–**D**). SPECT or planar scintigraphy using Tc-99 m sestamibi shows high radiotracer uptake in parathyroid adenoma (**Figure 26F**). Fusion SPECT–CT can aid in further localization. Brown tumor usually resolves after treatment of hyperparathyroidism in the form of surgical resection of parathyroid adenoma or medical treatment depending on the cause.
