Spinal Neoplasms Diagnostic Imaging Approach Part II

by Dr Alex Jimenez DC, APRN, FNP-BC, CFMP, IFMCP | Imaging & Diagnostics

Summary

• Neoplasms
• The vast majority of clinically suspected bone Mets are found in the axial skeleton and proximal femurs/humeri
• Radiography is the most cost-effective and readily available initial imaging tool to investigate bone Mets but often fails early metastatic detection
• Tc99 bone scintigraphy is the most sensitive and cost-effective imaging modality to demonstrate metastatic foci
• MR imaging may help� regional identification of bone Mets especially if x-radiography is unrewarding
• Significant limitations of MRI: inability to perform a whole-body MRI scan
• Cost and other contraindications such as cardiac pacemakers and cochlear implants may be another limiting factor

Marrow Based Neoplasms

• Malignancy originating from the marrow cells are often referred to as “round-cell tumors.”
• Multiple Myeloma (MM)
• Lymphoma
• Ewing’s sarcoma
• The last two are less frequent than MM

• Red marrow in adults is in the axial skeleton and proximal femurs/humeri d/t gradual marrow “retraction” following the childhood

• Note bone marrow biopsy histopathology specimen of MM with abnormal plasma cells replacing regular marrow residents (above image)
• Multiple Myeloma (MM) is the most common primary bone neoplasm in adults>40s. Etiology is unknown, but many theories exist (e.g., genetic, environmental, radiation, chronic inflammation, MGUS)
• MM: malignant proliferation of plasma cells >10% of red marrow, with subsequent replacement of normal marrow cells by myeloma cells and overproduction of monoclonal antibodies paraproteins (M protein) with heavy chains IgG (52%), IgA (21%), IgM (12%) and light chains kappa or lambda aka Bence-Jones proteins

Clinical Presentation of MM

• MM is occasionally detected as unexplained anemia on routine blood studies for unrelated complaints
• Common MSK symptoms: Bone pain/Pathologic fractures
• Constitutional: Weakness/malaise
• Systemic: bleeding, anemia, Infection (especially pneumococcal) d/t marrow replacement and pancytopenia
• Hypercalcemia d/t bone resorption
• Renal failure aka myeloma kidney
• Neuropathies
• Amyloidosis
• Gout

• Diagnostic imaging plays an essential role during the Dx of MM
• Bone marrow aspiration biopsy, blood tests, and serum protein electrophoresis may be used
• Imaging approach: bone pain is investigated with initial x-radiographs if radiographs are unrewarding MR imaging may help to reveal bone marrow abnormality. MRI is recommended as myeloma survey
• Currently, MRI protocol known as “whole body myeloma scan” consisting of T1, T2-fat suppressed, and T1+C coronal sequences can detect MM in the skull, spine, pelvis, ribs and femurs/humeri. This technique is much more superior to radiographic “skeletal myeloma survey.”
• Tc99 bone scintigraphy is not typically used for MM because over 30% of MM lesions are “cold” or photopenic on radionuclide bone scan d/t highly lytic nature of MM with osteoclasts outpacing osteoblasts.
• A radiographic skeletal survey is considered more sensitive than bone scintigraphy in MM
• PET-CT scanning of MM is gaining popularity due to the high level of detection of multiple sites of MM

• Radiographic Dx of MM: consists of identification of characteristically localized focal osteolytic “punched out” or “moth-eaten” lesions of variable sizes following the distribution of adults red marrow
• Note rad abnormality is known as “raindrop skull” is characteristic of MM

• Radiographic appearance of MM may vary from “punched out” round radiolucencies to “moth-eaten” or permeating osteolytic lesion producing endosteal scalloping (yellow arrow)

• Pelvis and femurs are commonly affected by MM and present radiographically as round lytic punched out or moth-eaten lesions
• N.B. Occasionally MM may pose radiographic dilemma by presenting as generalized osteopenia in the spine that can be difficult to differentiate from age-related osteoporosis

• MR imaging of MM reveals� marrow changes with low signal on T1, a high signal on fluid-sensitive sequences and bright contrast enhancement on T1+C gad d/t increased vasculature and high activity of� MM cells

• Example of full-body MRI of “whole body myeloma scan” with T2-fat suppressed (A), T1 (B) and T1+C (C) pulse sequences produced in coronal slices
• Note multiple foci of bone marrow changes in the spine pelvis and femurs

Miscellaneous Neoplasms of the Spinal Column

• Chordoma: is relatively uncommon but considered the m/c primary malignant neoplasm that only affects the spine. D/t slow growth is often misdiagnosed for a considerable length of time as LBP
• Pathology: derives from malignant transformation of notochordal cells presented as mucoid, gelatinous mass containing physaliphorous cells
• Demo:�M: F 3:1 (30-70S). 50%-sacrococcygeal, 35% spheno-occipital 15%-spine
• Clinically: asymptomatic for a long time until non-specific LBP, changes in bladder & bowel, neurological signs are less common d/t midline “outward” growth & inferior to S1. Local invasion worsens prognosis. 60%-survive 5-years, 40%-10-years, Mets are delayed, poor prognosis d/t local invasion. >50% can be id. on DRE.
• Imaging:�x-rays often tricky d/t overlying gas/feces. CT is >sensitive to id the bone mass and internal calcifications. MRI: T2 bight signal, T1 heterogeneously low and high d/t mucus/blood decomposition, MRI best detects local invasion and essential for care planning. Rx:� complete excision is often impossible d/t local vascular invasion.

• Giant cell tumor (GCT):�2nd most common primary sacral tumor. It is a histolgically benign neoplasm containing multinucleated Giant cells of Monocyte-Osteoclast origin
• Imaging Dx:�x-radiography is the 1st step usually in response to complaints of LBP. Often challenging to id on x-rays d/t bowel gas/feces
• Key rad feature: osteolytic expansile lesion noted by destruction of sacral arcuate lines. CT may id the lesion better. MRI is the modality of choice following x-rays. MRI: T1 low to intermediate signal. Heterogeneously high d/t edema with areas of low signal on T2 d/t blood degradation and fibrosis. Characteristic fluid-fluid levels may be noted especially if ABC develops within a GCT. Rx: operative. Prognosis is less favorable than GCT in long bones d/t lung Mets (deposits) in 13.7%

• Aneurysmal Bone Cysts (ABC) are benign expansile tumor-like bone lesions (not a true neoplasm) composed and filled with numerous blood-filled channels. Thus the term “blood sponge.” ABC is m/c id in children and adolescents
• Unknown etiology: trauma and pre-existing bone neoplasm (e.g., GCT) often reported. Clinically: pain that may be progressive d/t rapid nature of ABC expansion. In the spine, ABC m/c affects posterior elements and presented as expansile, soap-bubbly or lytic lesion.
• DDx: can be broad, but Osteoblastoma and GCT are the top DDxs.
• Imaging: x-rays demo expansile mass in posterior elements, CT is more sensitive than x-rays, MRI will demo characteristic fluid-fluid levels and mixed high and low signal d/t edema and blood decomposition/aging with some septations.
• N.B. MRI fluid-fluid levels are not exclusive to ABC, and DDx includes GCT, osteoblastoma, telangiectatic osteosarcoma.
• Rx: operative curettage and bone grafting, fibrosing agents. Recurrence 10-30%.

Spinal Neoplasms

Additional Resources

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4931792/
• https://emedicine.medscape.com/article/1267223-overview#a4
• https://www.ncbi.nim.nih.gov/pmc/articles/PMC2958273/
• http://bonetumor.org/

Spinal Neoplasms Diagnostic Imaging Approach Part I

by Dr Alex Jimenez DC, APRN, FNP-BC, CFMP, IFMCP | Imaging & Diagnostics

Metastatic Bone Disease (aka Mets) or “Secondaries.” Are the most common malignant bone neoplasms affecting the spine, aka spinal neoplasms (>70%) and the rest of the skeleton in adults.

• 5-Primaries are m/c involved:
• Breast (16-37%)
• Lung (12-15%)
• Thyroid (4%)
• Renal (3-6%)
• Prostate (9-15%)
• Spine, pelvis, proximal femurs & proximal humeri are m/c affected in that particular order of frequency
• Thoracic & upper Lumbar spine considered the m/c site of spinal Mets

Pathophysiology & Etiology of Metastasis

• Malignant cells a very good at evading immune detection and elimination
• They gain�access to circulation expressing Vascular Endothelial Adhesion Molecules (e.g., integrines & selectins)
• Once reaching their target organs, malignant cells stimulate the production of various vasogenic growth factors and by exiting blood vessels invade their target tissues
• Lung, Liver, and Bone are particularly at risk due to the character of their blood supply
• Baston venous plexus-is a network of valveless freely communicating� veins connecting axial skeleton/meninges and proximal femurs/humeri with abdomino-pelvic and thoracic cavities
• The risk of Mets is increased during daily variations in the intra-abdominal and intra-thoracic pressure

• In adults, the axial skeleton is involved in hematopoiesis, and it is particularly vulnerable to metastatic deposits via an abundant network of sinusoids within a spongy bone
• The vast majority of bone Mets will be detected in the axial skeleton

Clinical Presentation

• Back pain often mimicking “mechanical back pain” is the m/c and often misleading symptom
• Chiropractors and other manipulators should be particularly aware of this dangerous pitfall.
• Nocturnal pain or pain unresponsive to NSAID may be reported in more advanced cases
• Advanced cases may also present with a neurological deficit due to pathologic vertebral fractures and spinal cord/nerves compression
• Metastatic hypercalcemia may occasionally develop in severe cases and considered a medical emergency that potentially presents with confusion, muscle weakness, and renal signs
• Imaging plays a significant role in the Dx and management of bone metastasis
• Lab tests are of limited value, but hypercalcemia and alkaline phosphatase (Alk Phos) may be elevated
• In some cases, a bone biopsy may be used to confirm bone Mets

When Bone Mets are Detected, Patients Prognosis is Significantly Worsened

• Median survival:
• Thyroid – 48 – months
• Prostate – 40 – months
• Breast – 24 – months
• Renal Cell – may vary, can be as low as 6 – months
• Lung – 6 – months

Imaging Diagnosis

• Begins with radiography investigating a clinical complaint of back/bone pain
• If radiographs are unrewarding or equivocal, unique imaging modalities are required
• MRI may help to show marrow replacement by Mets foci but limited to specific regions
• Tc99 radionuclide bone scan (scintigraphy) is considered one of the most sensitive and reliable imaging steps in evaluating bone Mets
• Bone scintigraphy is good at detecting both lytic and blastic Mets
• However, very aggressive/vascular osteolytic Mets and Multiple Myeloma often appear “cold” or photopenic on bone scan due to greater stimulation/activation of osteoclasts which “outpace” osteoblasts ability to uptake the radiopharmaceutical
• CT scanning is an excellent modality to show bone destruction, but it is not widely used during bone Mets Dx especially if radiography, bone scintigraphy, and MRI provide adequate information about the process
• CT scanning may be particularly helpful with delineation of pathological fractures

General Radiographic Features of Bone Mets

• Osteolytic (lytic), osteoblastic (blastic) aka sclerotic Mets or misec Mets can be identified radiographically
• However, it takes between 30-50% of lamella (cortical) bone and 50-75% of trabecular (cancellous) or spongy bone to be destroyed before it can be detected on plain film radiographs
• This can make early radiographic detection of bone Mets very difficult, requiring particular imaging modalities (e.g., MRI)
• Also, bowel gas/fecal matter and numerous soft tissue densities in the abdomino-pelvic and thoracic cavities may pose challenges of bone Mets detection
• Different tumors often manifest with different metastatic appearance, depending on tumor activity and release of cytokines (IL6, IL11), endothelin 1 or other growth factors that will be responsible for either osteolytic, osteoblastic or mixed Mets
• For example: purely lytic bone Mets are noted in Lung, Thyroid, and Renal cell CA (very vascular)
• Breast CA may present with 60% of blastic Mets
• Prostate CA presents with 90% of blastic Mets
• Other blastic Mets may derive from urinary bladder, melanoma and GI adenocarcinomas
• Sclerotic foci may also represent as previously treated primaries
• Very vascular� Mets like Renal cell and Thyroid may present with markedly� lytic and expansile foci often called “blow out Mets.”
• Mets found distal to elbows and knees (acro-metastasis) are commonly associated with Lung CA

• PA chest view of a routinely screened patient with a known Hx of Prostatic adenocarcinoma
• Note sclerotic lesion identified in the left posterior Rib 5
• What imaging modality is required next?
• Radionuclide bone scan should be suggested

• Multiple foci of high uptake of the Tc99 radiopharmaceutical
• This is due to Mets and increased osteoblastic activity in the thoracic and lumbar spine, ribs and other sites of the skeleton

• Comparison of purely lytic (a and b) versus blastic (d) and mixed (c) Mets
• What primaries to consider?

• Frog leg view of the hip
• Clinical Dx: Prostatic adenocarcinoma
• Note diffuse blastic Mets in the proximal femur

• Hx: severe shoulder and arm pain unrelieved by rest
• Rad DDx: Mets, Myeloma or less frequently Lymphoma
• This classic DDx is used by the majority of Radiologists when aggressive osteolytic bone lesions are noted
• The patient had a known Hx of Breast CA

• A 51-year-old female with Breast CA
• Large lytic destructive lesion in the distal femoral metaphysis characteristic of aggressive osteolytic Mets

• Sudden onset of severe leg pain and inability to stand in a 53-year-old female with Breast CA
• Dx: Pathological fracture through the distal femoral shaft
• Pathological Mets fractures in the spine and extremities are dreaded by most Oncologists due to higher association with severe complications and poor clinical prognosis

• Radiographic Dx of vertebral Mets should be suspected if a “missing pedicle sign” aka “winking owl sign” is noted
• DDx: pedicle agenesis (above left) shows hypertrophy and sclerosis of a contralateral pedicle d/t increased mechanical stress
• Pedicle Mets are often thought of as the m/c initial site of spinal Mets

Vertebral Body Pathologic Fracture (VERTEBRA PLANA)

• Isolated compression fracture at the T8 segment noted (above arrow)
• The loss of the posterior and anterior height suggest an underlying pathologic condition for which the differential diagnosis includes:
• Multiple myeloma
• Metastatic Carcinoma
• Other malignancy
• Osteoporosis
• Differentiating Pathological Fx of the vertebral body from an osteoporotic insufficiency Fx can be a significant challenge
• Close inspection of the posterior body height is helpful but often not reliable
• In metastasis, the posterior body is collapsed
• In OSP, the posterior body may be maintained appearing more as anteriorly wedge fracture
• MR imaging and/or radionuclide bone scan need to be performed

• A skeletal radiographic survey may be used occasionally for the evaluation of bone Mets especially in well-established cases
• It includes bilateral AP & lateral Thoracic and Lumbar views, AP pelvis, humeri, femurs, and the skull
• Availability of special imaging has supplanted the use of skeletal radiographic survey
• However, in a clinical practice skeletal radiographic study of Multiple Myeloma may still be used primarily if the diagnosis was previously established

Technetium-99 (99mTc) bone scintigraphy is very sensitive and cost-effective study:

• For the detection/localization of Mets and often an assessment of their biologic activity and response to treatment
• This modality is a well-established part of the workup for known as well as unknown primaries
• It may also help with determination of lesions that will be most accessible and easy to biopsy

• When the burden of Mets is significantly high as shown in the case above
• The radiotracer uptake is being almost entirely taken in by metastatic lesions
• No material is left for the kidneys to excrete
• This is known as a “super scan”

• Sagittal Lumbar and Lower Thoracic MRI. Multiple metastasis are noted on T1 (above right) and T2 (above left)� WI as hypointense foci of marrow replacement of the vertebral bodies in a patient with Hx of Prostate CA
• MR imaging protocol with T1, T2, and T1+C gad can be used in many cases if x-radiography is unrewarding or questionable
• �MRI can reveal bone marrow changes due to bone marrow replacement by Mets and surrounding edema
• Typically blastic Mets appear as abnormally decreased signal intensity (hypointense) lesions on T1 and T2 pulse sequences
• Purely lytic Mets often appear as hypo-intense on T1 and hype-intense on T2
• Increased gadolinium uptake may also be evident on T1+C fat suppressed sequence d/t increased vascularity of malignant foci especially in very aggressive vascular neoplasms

Spinal Neoplasms