12.4 Tumors and Tumor-like Processes

12.4 Tumors and Tumor-like Processes

Quick Answer: Tumor imaging on Part II requires benign-versus-malignant discrimination using border, periosteal reaction, matrix mineralization, patient age, and lesion location — then stating the correct clinical impression and referral urgency. Any pathologic fracture, permeative destruction in a patient over 40, or night pain unrelieved by rest is an oncology red flag until proven otherwise. Run ABCS and explicitly ask: is there a soft-tissue mass?

Bone tumors and tumor-like processes account for a substantial share of Diagnostic Imaging pathology items. Unlike congenital variants (smooth margins, no aggression) or uncomplicated OA (joint-centered), neoplastic films test whether you recognize biologic behavior from static radiographs and connect findings to referral, not adjustment plans.

ABCS for Suspected Bone Neoplasm

1. Alignment — pathologic fracture deformity, impending fracture (large lytic femoral neck lesion)
2. Bone — lucent vs. sclerotic; zone of transition (narrow/geographic = benign tendency; wide/permeative = aggressive); cortex intact vs. destroyed
3. Cartilage — joint invasion (secondary osteoarthritis from intra-articular tumor); physis crossing in pediatric tumors
4. Soft tissues — soft-tissue mass strongly favors malignancy; benign lesions are usually confined within bone contour

Add two meta-questions: How old is the patient? and Where is the lesion (epiphysis, metaphysis, diaphysis, flat bone)?

Benign vs. Malignant Radiographic Features

Periosteal reaction primer:

• Solid/uninterrupted — benign or low-grade, healing fracture
• Onion-skin (lamellated) — Ewing sarcoma classic; also infection
• Sunburst (spiculated) — osteosarcoma classic
• Codman triangle — elevated periosteum at lesion margin with cortical break — aggressive

Age-and-Site Matrix (Part II Recognition)

Children and Adolescents

• Osteosarcoma — Peak teens; metaphysis of long bones (distal femur, proximal tibia most common); osteoid matrix (cloud-like density); sunburst periostitis; aggressive
• Ewing sarcoma — Children/young adults; diaphysis of femur/pelvis; permeative lucency; onion-skin periostitis; "moth-eaten" pattern
• Osteochondroma — Most common benign bone tumor; sessile or pedunculated exostosis with corticomedullary continuity with parent bone; metaphysis near physis
• Unicameral bone cyst (UBC) — Children/teens; proximal humerus, proximal femur metaphysis; centrally located, fall risk → pathologic fracture ("fallen fragment" sign)
• Aneurysmal bone cyst (ABC) — Metaphysis; expansile, eccentric, fluid-fluid levels on MRI; may be secondary to other lesions

Adults Over 40

• Metastasis — Most common malignant bone tumor in adults; multiple lytic (or blastic) lesions; breast, lung, prostate, kidney, thyroid primaries; vertebral body predilection; pedicle sparing less reliable than taught but vertebral involvement is classic stem
• Multiple myeloma — Punched-out lytic lesions without sclerotic rim; vertebra plana (compression); "raindrop skull"; age >50
• Enchondroma — Hands (phalanges, metacarpals), benign cartilaginous matrix; usually incidental; chondrosarcoma transformation if painful enlargement in adult
• Paget disease — Not neoplasm but tested with tumors; cotton-wool skull, picture-frame vertebra, blade-of-grass advancing lysis/sclerosis; risk of osteosarcoma transformation (rare)

Specific Lesions: Recognition and Referral

Osteoid Osteoma

• Nidus: Small (<1.5 cm) radiolucent center with dense surrounding sclerosis
• Location: Cortex of femur/tibia; posterior elements of spine
• Clinical: Night pain dramatically relieved by NSAIDs — pathognomonic clue in stem
• Referral: Orthopedic interventional (radiofrequency ablation) if symptomatic; benign but debilitating

Osteoblastoma

• Larger (>2 cm) cousin of osteoid osteoma; spine posterior elements; NSAID response less dramatic; surgical excision more often needed

Giant Cell Tumor (GCT)

• Epiphysis after physeal closure (unlike most benign tumors in metaphysis); eccentric, lytic, "soap bubble" expansile appearance; locally aggressive — orthopedic oncology referral

Fibrous Dysplasia

• Ground-glass matrix; expands bone; monostotic (one bone, often rib/femur) vs. polyostotic (McCafe-Albright with café-au-lait spots)
• Shepherd's crook deformity of proximal femur in polyostotic form
• Benign; refer for fracture risk and deformity

Chondrosarcoma

• Cartilaginous matrix with ring-and-arc calcification; pelvic, proximal femur, shoulder; painful enlargement of prior enchondroma — urgent oncology referral

Spinal Tumors: Extra Caution

Cord compression from epidural metastasis may show only vertebral collapse on plain film — MRI is definitive; any progressive deficit = emergency.

Tumor-like Processes vs. True Neoplasms

• Bone infarct — Serpiginous sclerotic border, metaphysis/diaphysis; usually incidental
• Brown tumor of hyperparathyroidism — Multiple lytic lesions mimicking metastasis; subperiosteal resorption on hand films; check calcium/PTH
• Eosinophilic granuloma (Langerhans) — Children; vertebra plana with preserved disc height; skull lytic lesions

Part II may test whether you recognize metabolic mimic of metastasis — always correlate age, labs in stem, and lesion morphology.

Red Flags Demanding Urgent Referral

1. Pathologic fracture through lytic lesion
2. Progressive night pain not relieved by NSAIDs or rest
3. Unexplained weight loss, fever, history of cancer
4. Neurologic deficit with vertebral lesion
5. Permeative diaphyseal lesion in child (Ewing) or metaphyseal aggressive lesion in teen (osteosarcoma)
6. Soft-tissue mass with bone destruction

Do not initiate high-velocity manipulation through an undiagnosed lytic spinal lesion.

Part II Clinical Impression Framework

When the question asks for "most likely diagnosis" vs. "best next step":

• Diagnosis items — apply age + site + periosteal reaction + matrix
• Management items — malignant pattern → referral and MRI/biopsy pathway, not repeat radiographs in six weeks
• Distractors — chronic infection (Brodie abscess) mimics osteoid osteoma; eosinophilic granuloma mimics metastasis in child

Quick Reference Table

Tumor imaging on Part II is a safety discipline: recognize aggression, respect red flags, and route patients to oncology and orthopedic specialists when plain films show behavior that chiropractic care alone cannot address.