Chondrosarcoma

Slide 1 · Chondrosarcoma

Malignant cartilage-producing tumors of bone

Classification · Pathogenesis · Morphology · Prognosis

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Classify the major chondrosarcoma subtypes and recognize their distinct presentations.

Relate EXT1/EXT2, IDH1/IDH2 and CDKN2A alterations to their stated disease contexts.

Identify radiologic, gross and histologic evidence of cartilage-producing malignancy.

Explain how grade and skeletal location influence recurrence, metastasis and treatment.

Slide 3 · Defining feature of chondrosarcoma

Malignant tumor that produces cartilage

Cartilaginous matrix defines the phenotype of this bone malignancy.

The presence of cartilage alone does not establish malignancy: Benign cartilage tumors also exist.

Slide 4 · Matrix-producing malignancies

Osteosarcoma

Malignant bone tumor

Produces neoplastic bone or osteoid matrix

Chondrosarcoma

Malignant bone tumor

Produces cartilaginous matrix

Chondrosarcoma as second to osteosarcoma among malignant matrix-producing bone tumors.

Slide 5 · Cartilage matrix: What is being produced?

Schematic cartilage lacunae and chondrocytes

Interpretation

A cartilage matrix contains chondrocytes in lacuna-like spaces.

Histologic interpretation requires architecture and cytologic features, not matrix recognition alone.

This drawing is conceptual; It does not depict an actual tumor.

Slide 6 · Four major chondrosarcoma subtypes

Subtype

Key distinguishing source feature

Conventional

Hyaline cartilage-producing; dominant subtype

Clear cell

Large cells with clear cytoplasm; often epiphyseal

Dedifferentiated

Low-grade cartilage tumor plus high-grade noncartilaginous component

Mesenchymal

Primitive small round cells with islands of cartilage

Slide 7 · Conventional subtype predominates

Approximately 90% of chondrosarcomas are conventional

This group chiefly drives the typical epidemiologic and anatomic description.

Nonconventional subtypes must not be forced into the conventional age–site profile.

Slide 8 · Typical demographic profile

Conventional chondrosarcoma

Usually presents in the fourth decade or later.

Men are affected about twice as often as women.

Selected nonconventional subtypes

Clear-cell and mesenchymal variants can present in the teens or 20s.

Distinct age distribution may influence the morphologic differential.

Slide 9 · Usual skeletal distribution

Axial skeletal sites are prominent in conventional disease.

Pelvis, shoulder region and ribs are characteristic locations.

Distal extremities are rarely involved, unlike many benign enchondromas.

Slide 10 · Site as a diagnostic clue

Conventional chondrosarcoma

Often located in pelvis, shoulder or ribs.

Concerning in the setting of pain and progressive growth.

Benign enchondroma

Frequently occurs in tubular bones of hands and feet.

May be found incidentally without pain.

Anatomic predilection is supporting context, not a stand-alone histologic diagnosis.

Slide 11 · Two origins of conventional disease

Primary (de novo) tumor

Secondary tumor in an existing cartilage lesion

Conventional chondrosarcoma may arise without an identified benign precursor.

A subset develops in association with an enchondroma or an osteochondroma.

Slide 12 · Secondary chondrosarcoma

Approximately 15% of conventional cases arise secondarily

Recognized antecedents include enchondroma and osteochondroma.

This proportion refers to conventional chondrosarcoma as, not all variants.

Slide 13 · Osteochondroma and secondary risk

Cartilage-capped bony outgrowth

Preexisting osteochondroma

Possible secondary chondrosarcoma

Secondary malignancy is rare in the overall osteochondroma population.

The background is especially relevant in multiple hereditary exostoses.

Slide 14 · Enchondroma and secondary risk

Benign intramedullary cartilage lesion

Enchondromatosis context

Increased concern for malignant progression

Sporadic solitary enchondromas rarely undergo sarcomatous transformation.

Enchondromatosis is a more important risk setting.

Slide 15 · Enchondromatosis syndromes

Ollier disease

Multiple enchondromas.

Nonhereditary enchondromatosis syndrome.

Maffucci syndrome

Multiple enchondromas.

Also associated with spindle-cell hemangiomas and other neoplasms.

Slide 16 · Pathogenesis is genetically heterogeneous

No single driver explains all chondrosarcomas

Recurrent molecular alterations include EXT1/EXT2, IDH1/IDH2 and CDKN2A silencing.

Their frequency, context and interpretation differ; Avoid treating them as universal diagnostic tests.

Slide 17 · EXT1 / EXT2-associated setting

EXT1 / EXT2 alteration

Multiple osteochondroma syndrome

Occasional secondary chondrosarcoma

The source links these alterations to chondrosarcoma in multiple osteochondroma syndrome.

The gene products participate in matrix-associated glycosylation pathways.

Slide 18 · Why EXT function matters in precursors

EXT1 / EXT2 glycosyltransferases

Heparan sulfate biosynthesis

Growth-plate signaling organization

In osteochondroma, reduced EXT function can disturb chondrocyte polarity and signaling.

Do not infer a single deterministic EXT-to-sarcoma pathway from this context.

Slide 19 · IDH-related tumor setting

IDH1 / IDH2 mutation

Chondromatosis-related tumors

Also found in sporadic chondrosarcoma

An IDH alteration identifies a molecular association, not by itself a malignancy grade.

Slide 20 · IDH gain of function: Precursor context

Mutant IDH enzyme

2-hydroxyglutarate production

Disrupted DNA methylation regulation

This mechanistic sequence for enchondroma.

Consequences for differentiation, proliferation and survival are context-dependent; This is not a complete transformation model.

Slide 21 · CDKN2A epigenetic silencing

CDKN2A locus methylation

CDKN2A silencing

Source identifies the silencing event, without a claimed diagnostic sensitivity or predictive therapeutic role.

Slide 22 · Interpreting molecular alterations

Finding

Robbins context

What it does not prove

EXT1 / EXT2

Multiple osteochondroma-associated lesions

Not present in every chondrosarcoma

IDH1 / IDH2

Chondromatosis-related and sporadic lesions

Does not alone distinguish benign from malignant cartilage

CDKN2A methylation

Common sporadic tumor alteration

Not a quantified universal prognostic marker

Slide 23 · Clinical presentation: Pain and enlargement

Typically presents with a painful mass.

Progressive enlargement is a characteristic clinical pattern.

Pain and growth must be integrated with lesion location, imaging and morphology.

Slide 24 · Clinical reasoning begins with a time course

Patient notices a mass

Progressive enlargement

Pain prompts evaluation

The usual complaint reflects a progressively expanding cartilage-producing lesion.

A clinical history alone cannot establish histologic grade.

Slide 25 · Imaging evidence of cartilage matrix

Calcified tumor matrix produces flocculent densities on imaging.

Mineralization supports a chondroid matrix-producing lesion.

Cortical reaction or destruction helps assess local aggressiveness.

Slide 26 · Slow-growing lesion: Reactive cortex

Cortex retained

Cortex breached

Interpretation

A retained or thickened cortex can occur with a slowly growing, low-grade tumor.

Cortical disruption and extracortical extension are more concerning features.

Both panels are explanatory representations, not patient scans.

Slide 27 · The cortex records tumor behavior

Slow-growing low-grade disease

May induce reactive cortical thickening.

Can remain locally confined in appearance.

Aggressive high-grade disease

Cortical destruction is characteristic.

Extension into soft tissues may produce a mass.

Slide 28 · From medullary growth to tissue invasion

Cartilaginous lobules permeate marrow

Pre-existing bony trabeculae are entrapped

Interpretation

Tumor permeates marrow and surrounds existing bone trabeculae.

Extracortical extension may involve adjacent muscle or fat.

Apparent lobulation does not exclude infiltrative behavior.

Slide 29 · Imaging clues and pathologic interpretation

Observed feature

Interpretation supported by the source

Flocculent matrix densities

Mineralization within chondroid matrix

Reactive cortical thickening

May accompany slower low-grade growth

Cortical destruction

Evidence of aggressive local behavior

Soft-tissue mass

Extracortical tumor extension

Slide 30 · Why axial site matters in management

Pelvis and other axial sites can make local disease control difficult.

Local recurrence is particularly problematic in limb girdles and axial skeleton.

Anatomical site modifies prognosis beyond histologic grade alone.

Slide 31 · Gross appearance: A nodular cartilage tumor

Conventional tumors may be bulky.

Cut surfaces show nodules of glistening gray-white, translucent cartilage.

Gross appearance may suggest a cartilage-producing tumor but cannot establish grade by itself.

Slide 32 · Two gross matrix textures

Firm / translucent cartilage

Glistening gray-white cartilage nodules.

Cartilage matrix forms the major tumor substance.

Gelatinous / myxoid matrix

Focally softer, gel-like material.

Myxoid matrix may ooze from the cut surface.

Slide 33 · Gross secondary changes

Focal calcification may interrupt otherwise translucent cartilage.

Central necrosis may create cystic spaces.

These components contribute to gross and imaging heterogeneity.

Slide 34 · Gross tumor extension

Medullary cartilage nodules

Cortical permeation / destruction

Extension into muscle and fat

Extracortical growth is frequent in established conventional tumors.

Interpret the full margin and surrounding tissue interface.

Slide 35 · Permeative growth within marrow

Cartilaginous lobules permeate marrow

Pre-existing bony trabeculae are entrapped

Interpretation

Cartilage surrounds pre-existing bony trabeculae.

Permeation is an architectural clue to malignant cartilage-producing growth.

Native diagram intentionally omits true microscopic textures.

Slide 36 · Entrapped trabeculae: Why they matter

Malignant cartilaginous tissue may infiltrate the marrow space.

Pre-existing bony trabeculae become enclosed by the neoplastic cartilage.

This architectural finding complements cellularity and nuclear atypia.

Slide 37 · Benign enchondroma versus malignancy

Enchondroma

Well-circumscribed nodule of hyaline cartilage.

Cortex usually intact; Peripheral reactive bone may surround lesion.

Chondrosarcoma

Cartilage can permeate marrow and surround trabeculae.

Cortical destruction and extracortical growth may occur.

Slide 38 · Why cellular atypia is not the whole diagnosis

Benign cartilaginous tumors can show some increased cellularity or atypia in syndromic settings.

A low-grade chondrosarcoma may have only modest cytologic abnormalities.

Tumor architecture, imaging, symptoms and location therefore matter together.

Slide 39 · Conventional histologic grade is multidimensional

Cellularity

Cytologic atypia

Mitotic activity

Grades 1–3 correlate with biologic behavior and prognosis.

The source does not specify numeric scoring cutoffs for the three variables.

Slide 40 · Grade 1 chondrosarcoma: Subtle cytology

Typically has low cellularity.

Neoplastic chondrocytes possess plump vesicular nuclei and small nucleoli.

Cytologic blandness must be interpreted together with infiltrative growth.

Slide 41 · Grade 3 chondrosarcoma: Overt malignancy

High cellularity is typical.

Extreme nuclear pleomorphism is present.

Mitotic figures are frequent; Risk of hematogenous metastasis is much higher.

Slide 42 · Grade 2: Between the textbook poles

Conventional chondrosarcoma is graded 1, 2 or 3.

The extracted Robbins passage provides detailed descriptors for grades 1 and 3, but not an independent grade-2 scoring algorithm.

Intermediate-grade assignment requires complete histologic assessment rather than interpolation from a schematic.

Slide 43 · Cellularity and atypia across grades

Grade 1

Grade 2

Grade 3

Interpretation

The conceptual panels show increasing cellularity and nuclear variation.

They are schematic, not WHO grading micrographs or quantitative thresholds.

Grade is assigned on actual sampled tumor morphology.

Slide 44 · Low versus high grade: Linked domains

Grade 1 pattern

Low cellularity and relatively mild cytologic atypia.

May show reactive cortical change on imaging.

Grade 3 pattern

Marked pleomorphism and many mitoses.

Aggressive cortical destruction and metastatic potential.

Slide 45 · Dedifferentiated variant: Two components

Low-grade chondrosarcoma

Abruptly distinct second component

High-grade noncartilaginous sarcoma

The defining feature is juxtaposition of differentiated cartilage and high-grade noncartilage tissue.

Slide 46 · Dedifferentiated morphology is biphasic

Cartilaginous component

Noncartilaginous high-grade cells

Interpretation

The two components differ in matrix production.

Sampling only the cartilage component could miss the high-grade component.

This is a conceptual sampling pitfall, not a source-specific diagnostic algorithm.

Slide 47 · Clear-cell variant: Distinct profile

Clinical / anatomic pattern

May occur in teens or 20s.

Arises in epiphyses of long tubular bones.

Microscopy

Sheets of large atypical chondrocytes with clear cytoplasm.

Osteoclast-type giant cells and intralesional bone formation.

Slide 48 · Clear-cell morphology: Multiple tissue elements

Abundant clear cytoplasm in large atypical tumor cells.

Numerous osteoclast-type giant cells.

Bone formation within the lesion: Part of its described morphology.

Slide 49 · Mesenchymal subtype: Age and architecture

Clinical context

Often affects younger patients, including teens or 20s.

Unlike conventional disease, age distribution is not dominated by older adults.

Microscopy

Islands of differentiated hyaline cartilage.

Primitive small-round-cell sheets around the cartilage.

Slide 50 · Mesenchymal pattern: Cartilage islands

Cartilage islands in primitive-cell background

Interpretation

Well-differentiated hyaline cartilage appears as discrete islands.

Sheets of primitive-appearing small round cells surround those islands.

This schematic is not a bona fide H&E section.

Slide 51 · Subtype recognition: One decisive pattern

Subtype

Distinguishing tissue feature

Conventional

Infiltrative hyaline/myxoid cartilage; graded 1–3

Dedifferentiated

Low-grade cartilage component plus high-grade noncartilage tumor

Clear cell

Large clear-cytoplasm chondrocytes, giant cells and bone

Mesenchymal

Small round cells with discrete hyaline cartilage islands

Slide 52 · Integrated diagnosis is more than one feature

Identify chondroid matrix and the growth pattern.

Examine the interface with marrow, cortex and adjacent tissues.

Assess cytologic atypia, cellularity and mitoses.

Integrate grade with age, site and imaging phenotype.

Slide 53 · Key benign–malignant comparison

Features favoring enchondroma

Well-defined intramedullary cartilage nodule.

Preserved cortex, possibly a thin reactive bony rim.

Often incidental in small tubular bones.

Features favoring chondrosarcoma

Painful progressively enlarging mass.

Permeation around trabeculae.

Potential cortical destruction or soft-tissue extension.

Slide 54 · Limits of a small biopsy or isolated image

The sampled region may not represent all tumor components.

Grading depends on evaluable tumor morphology and the interface with host bone.

An isolated image cannot reliably demonstrate the patient’s symptoms, full cortical behavior or site.

Slide 55 · Histologic grade predicts behavior

Grade 1: Predominantly local risk

Increasing histologic aggressiveness

Grade 3: High metastatic potential

Source directly associates grade with outcome, including metastasis and survival.

Site influences consequences of local failure.

Slide 56 · Grade 1: Local recurrence remains relevant

Approximately 10% local recurrence

Grade 1 tumors rarely metastasize.

Despite excellent overall survival, recurrent disease can cause major morbidity.

Slide 57 · Grade 1: Excellent reported survival

Five-year survival close to 100%

This is the textbook estimate for grade 1 disease; It is not a prediction for an individual patient.

Clinical location and local control still matter.

Slide 58 · Local recurrence is not uniformly harmless

Axial and limb-girdle sites are especially challenging for local control.

Mortality in grade 1 disease can result from local recurrence.

Grade alone does not capture surgical accessibility and risk.

Slide 59 · Grade 3: Hematogenous metastasis

Primary bone lesion

Lung metastasis

Hematogenous dissemination

Interpretation

Most grade 3 tumors spread through the bloodstream.

The lungs are a particularly important metastatic site.

This pathway is schematic and does not encode metastasis rates.

Slide 60 · Grade 3: Markedly poorer outcome

Five-year survival less than 50%

Textbook estimate for grade 3 tumors.

Most grade 3 chondrosarcomas disseminate hematogenously, especially to the lungs.

Slide 61 · Terminology in low-grade extremity disease

Grade 1 chondrosarcoma

Traditionally indicates a low-grade malignant cartilaginous neoplasm.

Textbook notes that metastasis is rare.

Atypical cartilaginous tumor

Proposed label for grade 1 lesions of long bones of extremities.

Emphasizes their favorable behavior at this anatomic site.

Terminology is site-dependent; Do not extend the same prognosis to equivalent-appearing axial tumors.

Slide 62 · Treatment tracks tumor risk and location

Grade 1, selected sites

Possible intralesional curettage

Higher grade / nonappendicular sites: Wide excision

Surgery is the principal treatment.

Site, grade and appropriate case selection govern treatment extent.

Slide 63 · Surgery: Selective local versus wide treatment

Selected grade 1 case

Curettage may be appropriate in selected cases.

Requires careful assessment of local risk.

Higher-grade or axial/nonappendicular case

Wide surgical excision is the described approach.

The anatomic challenge of achieving margins is clinically relevant.

Slide 64 · Case 1: Painful expanding pelvic mass

Hypothetical vignette

An older adult has progressive pelvic pain and an enlarging lesion. Imaging suggests calcified cartilage matrix, cortical destruction and extension into adjacent soft tissue.

Interpretation prompts

Which subtype is most compatible with this age–site profile?

What features indicate aggressive local behavior?

Slide 65 · Case 1: Interpretation

Reasoning from provided findings

Conventional chondrosarcoma is compatible with the older age and pelvic location.

Flocculent mineralization supports chondroid matrix; Cortical destruction and soft-tissue extension signify aggressiveness.

Grade still requires microscopic assessment; Imaging alone cannot assign grade 3.

Slide 66 · Case 2: Epiphyseal lesion in a young adult

Hypothetical vignette

A patient in their early 20s has a cartilage-producing tumor centered in the epiphysis of a long bone. Histology shows large cells with clear cytoplasm and osteoclast-type giant cells.

Interpretation prompts

Which subtype best integrates the site and morphology?

Which additional described tissue component might occur?

Slide 67 · Case 2: Interpretation

Reasoning from provided findings

Clear-cell chondrosarcoma best fits the epiphyseal origin and large clear-cytoplasm chondrocytes.

Intralesional bone formation is another described microscopic feature.

The conventional older-adult axial-site pattern should not be imposed on this subtype.

Slide 68 · Case 3: A low-grade extremity lesion

Hypothetical vignette

A long-bone cartilage tumor has low cellularity and subtle atypia. Imaging shows limited local aggressiveness and microscopic sampling raises grade 1 conventional chondrosarcoma.

Interpretation prompts

What alternative site-dependent term does Robbins discuss?

What prognosis and local issue should be explained?

Slide 69 · Case 3: Interpretation

Reasoning from provided findings

Atypical cartilaginous tumor is the source-discussed alternative terminology for grade 1 lesions in long bones of extremities.

Metastasis is rare and the estimated five-year survival approaches 100%, but local recurrence remains possible.

An equivalent low-grade lesion in an axial site requires greater attention to difficult local control.

Slide 70 · Synthesis: Grade, site and clinical action

Domain

Low-grade setting

Aggressive setting

Architecture

May have permeation despite bland cytology

Often more destructive and infiltrative

Cytology

Low cellularity; relatively mild atypia

Marked pleomorphism; frequent mitoses

Biologic risk

Mainly local recurrence

Hematogenous dissemination, especially lung

Operative strategy

Selected grade 1 lesions: curettage

Higher-grade/nonappendicular: wide excision

Slide 71 · Final diagnostic synthesis

A malignant cartilage-producing bone tumor is identified by matrix, growth pattern and clinical–radiologic context.

Conventional, clear-cell, dedifferentiated and mesenchymal variants have distinct morphology.

EXT1/EXT2, IDH1/IDH2 and CDKN2A changes are contextual—not universal grading substitutes.

Grade and anatomic site jointly inform recurrence, metastatic potential and surgery.

Slide 72 · Principal reference and editorial limitations

Robbins, Cotran & Kumar

Pathologic Basis of Disease, 11th edition (2026)

Chapter 26 — Bones, Joints, and Soft Tissue Tumors, pp. 1080–1084

Source note: extracted Markdown interleaves the chondrosarcoma morphology text with the next section. The relevant continuation was recovered and included.

All tissue, cell, radiologic and metastasis drawings are native, editable teaching schematics, not diagnostic specimens.