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Mastering the Osteochondroma Examination Question

Ace the Enchondroma Examination Question: Diagnosis & Management

23 Apr 2026 56 min read 126 Views
Illustration of examination question enchondroma - Dr. Mohammed Hutaif

Key Takeaway

Looking for accurate information on Ace the Enchondroma Examination Question: Diagnosis & Management? An enchondroma is a benign, well-defined cartilaginous tumor often presenting as an expansile, lytic lesion with stippled calcification. For an examination question enchondroma, diagnosis requires a full history, physical exam, MRI, and bone tumor MDT discussion. Surgical treatment typically involves curettage. Malignant transformation is rare for solitary lesions but higher in enchondromatosis conditions.

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Question 1

A 35-year-old male presents with incidental discovery of a lucent lesion with punctate calcifications in the metadiaphysis of the proximal phalanx of his hand. No pain or swelling. What is the most likely diagnosis?





Explanation

Enchondromas are the most common benign cartilaginous tumors of the small bones of the hands and feet. Their classic radiographic appearance includes a lucent, intramedullary lesion with characteristic punctate or rings-and-arcs calcifications. The asymptomatic nature and typical location strongly favor enchondroma. Chondrosarcoma is less likely given the benign radiographic features and lack of symptoms. Osteochondroma is an exostosis, not intramedullary. Fibrous dysplasia has a ground-glass matrix. Giant cell tumor is typically epiphyseal and purely lytic.

Question 2

When differentiating a solitary enchondroma from a low-grade chondrosarcoma in a long bone, which of the following radiographic features is most concerning for malignancy?





Explanation

Significant endosteal scalloping, particularly when it exceeds 2/3 of the cortical thickness, is a key radiographic indicator that suggests a more aggressive lesion, such as a low-grade chondrosarcoma, rather than a benign enchondroma. Punctate calcifications are typical for both. Intralesional fat is often seen in bone infarcts or areas of marrow, not typically a chondroid tumor. A well-defined sclerotic border and absence of periosteal reaction are features more consistent with a benign lesion.

Question 3

A 40-year-old female has an asymptomatic enchondroma incidentally found in her proximal humerus during a shoulder MRI for rotator cuff impingement. The lesion measures 2x3cm, shows typical chondroid matrix calcifications, and no cortical breach or periosteal reaction. What is the most appropriate initial management?





Explanation

For an asymptomatic, radiographically benign-appearing enchondroma in a low-stress location like the proximal humerus, observation with serial radiographic follow-up (typically annual for 2-3 years) is the standard initial management. Surgical intervention, biopsy, or more aggressive treatments are reserved for symptomatic lesions, those with concerning radiographic features, or evidence of progression.

Question 4

A 12-year-old boy presents with multiple enchondromas affecting the long bones of one limb and multiple cutaneous hemangiomas. This presentation is most consistent with:





Explanation

Maffucci's syndrome is characterized by multiple enchondromas and cutaneous hemangiomas. Ollier's disease involves multiple enchondromas without hemangiomas. McCune-Albright syndrome involves fibrous dysplasia, café-au-lait spots, and endocrine dysfunction. Neurofibromatosis Type 1 features neurofibromas and café-au-lait spots. Gorlin syndrome (Basal Cell Nevus Syndrome) involves multiple basal cell carcinomas and jaw keratocysts.

Question 5

Histological examination of a typical enchondroma would reveal which of the following?





Explanation

A benign enchondroma typically consists of mature hyaline cartilage with small, uniform chondrocytes usually confined to single lacunae, or occasionally a few in pairs. There is no significant cellular atypia, binucleation, or myxoid change seen in low-grade chondrosarcoma. The other options describe features of other bone tumors: osteosarcoma (atypical cells), giant cell tumor (sheets of polygonal cells, osteoclast-like giant cells), fibrous histiocytoma (storiform pattern).

Question 6

A 28-year-old male sustains a pathological fracture through an enchondroma in his proximal humerus. What is the recommended management after initial stabilization?





Explanation

When a pathological fracture occurs through an enchondroma, the fracture should be allowed to heal initially. Once there is radiographic evidence of healing (typically 3-6 months), the patient can then undergo intralesional curettage of the enchondroma and bone grafting to prevent recurrence and address the underlying lesion. Immediate excision is usually not necessary or practical in the acute fracture setting. Radiation therapy and bisphosphonates are not standard treatments for enchondromas.

Question 7

Which of the following conditions is associated with the highest risk of malignant transformation of enchondromas into chondrosarcoma?





Explanation

Maffucci's syndrome carries the highest risk of malignant transformation (20-100%), often progressing to chondrosarcoma, but also to other malignancies. Ollier's disease also has a significant risk (25-50%), but generally lower than Maffucci's. Solitary enchondromas have a very low risk (<1%). Fibrous dysplasia and osteochondromatosis are different pathologies with their own distinct risks.

Question 8

On MRI, a benign enchondroma typically demonstrates which of the following signal characteristics?





Explanation

Benign hyaline cartilage, as seen in an enchondroma, typically appears low signal on T1-weighted images and very high signal on T2-weighted images due to its high water content. It often shows a lobulated configuration with internal septations and peripheral enhancement after contrast, but typically not solid or aggressive enhancement. Fluid-fluid levels are characteristic of aneurysmal bone cysts, and perilesional edema with cortical destruction is indicative of malignancy or infection.

Question 9

While enchondromas can occur in any bone, they are most frequently found in which anatomical location?





Explanation

Enchondromas are most commonly found in the small tubular bones of the hands and feet (phalanges, metacarpals, metatarsals). While they can occur in long bones like the humerus and femur, the appendicular skeleton, particularly the distal extremities, is their most frequent site.

Question 10

A 50-year-old patient with a history of corticosteroid use presents with hip pain. Radiographs show a lucent lesion with central calcifications in the femoral head. On MRI, the lesion has a "double-rim" sign. This feature is most characteristic of:





Explanation

The "double-rim" sign on MRI (a low signal intensity outer rim and a high signal intensity inner rim on T2-weighted images) is pathognomonic for osteonecrosis or bone infarct. Central calcifications can sometimes be seen within a bone infarct, which can be in the differential for a calcified intramedullary lesion, but the MRI features are distinct. Enchondromas generally do not present with this sign.

Question 11

Recent molecular studies have identified mutations in which gene family as commonly associated with enchondromas and low-grade chondrosarcomas?





Explanation

Somatic mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 genes are now recognized as common genetic alterations in both solitary enchondromas and central low-grade chondrosarcomas. These mutations lead to the production of an oncometabolite, 2-hydroxyglutarate (2-HG), which plays a role in chondrogenesis and malignant transformation.

Question 12

A 60-year-old male presents with dull, constant pain in his distal femur. Radiographs show a 4 cm intramedullary lesion with a lobulated contour, speckled calcifications, and mild endosteal scalloping (<1/3 cortical thickness). A recent MRI shows no clear cortical breach or soft tissue mass, but increased tracer uptake on bone scan compared to previous studies. What is the most appropriate next step?





Explanation

New onset or worsening pain in a chondroid lesion, especially in a long bone of an older patient, coupled with increased tracer uptake on a bone scan (suggesting metabolic activity), are concerning signs for malignant transformation to chondrosarcoma, even if other radiographic features are subtle. A definitive diagnosis requires a biopsy (either open or image-guided core biopsy if sufficient tissue can be obtained) to assess the histology and grade the tumor.

Question 13

What is a potential limitation of intralesional curettage for enchondromas, particularly in the long bones?





Explanation

The main limitation and most common complication of intralesional curettage for enchondromas is local recurrence, particularly if the curettage is incomplete and microscopic cartilaginous nests are left behind. Malignant transformation is not induced by the procedure. Curettage provides ample tissue for diagnosis. While a temporary weakening of the bone occurs, pathological fracture risk is generally lower than if left untreated or in some other tumor types.

Question 14

A patient undergoes curettage and bone grafting for a symptomatic enchondroma in the proximal humerus. Which of the following is the most common complication of this procedure?





Explanation

Local recurrence is the most common complication following intralesional curettage of enchondromas. This is typically due to incomplete removal of the cartilaginous lesion. While infection, nerve injury, and graft-related issues can occur, they are less frequent than local recurrence.

Question 15

Following successful curettage and bone grafting of an enchondroma, what is the typical recommended radiographic follow-up schedule?





Explanation

After curettage and bone grafting of an enchondroma, long-term radiographic follow-up is generally recommended to monitor for recurrence or malignant transformation. A common protocol involves annual radiographs for approximately 5 years, and then as needed based on clinical symptoms or any suspicious findings. More frequent imaging or advanced modalities are typically reserved for symptomatic lesions or those with concerning features.

Question 16

An enchondroma-like lesion in which of the following locations carries the highest intrinsic risk of being a low-grade chondrosarcoma, even if radiographically benign-appearing?





Explanation

Chondroid lesions in the axial skeleton (pelvis, scapula, sternum, ribs) and proximal long bones (femur, humerus) carry a higher intrinsic risk of being a low-grade chondrosarcoma compared to those in the small bones of the hands and feet or more distal long bones, even when imaging features appear benign. Lesions in the pelvis, in particular, are notorious for challenging differentiation and a higher index of suspicion for malignancy is warranted.

Question 17

What is the primary purpose of bone grafting after curettage of an enchondroma?





Explanation

After intralesional curettage of an enchondroma, a cavity remains. Bone grafting (autograft or allograft) is performed to fill this defect, provide structural support to the bone, and create a scaffold for new bone formation, thereby promoting healing and reducing the risk of pathological fracture. It does not induce malignancy, prevent infection (though careful aseptic technique is vital), or serve as a biopsy marker.

Question 18

A purely lytic, expansile lesion without internal calcifications in the metadiaphysis of a long bone would make enchondroma less likely and raise suspicion for what differential?





Explanation

Enchondromas typically contain chondroid matrix calcifications, though occasionally they can be purely lytic. However, a purely lytic, expansile lesion, especially without internal calcifications, makes enchondroma less likely. An aneurysmal bone cyst (ABC) is a strong differential for such a presentation, often being expansile and purely lytic. Fibrous dysplasia typically has a 'ground-glass' matrix. Non-ossifying fibroma and osteoid osteoma have characteristic appearances, but are not usually expansile in this manner without calcifications as the primary distinguishing factor. Bone infarcts often have calcified rims or serpiginous patterns.

Question 19

A key characteristic distinguishing Ollier's disease from solitary enchondroma is:





Explanation

Ollier's disease is characterized by multiple enchondromas, typically with an asymmetric or unilateral distribution affecting the long bones. This distinguishes it from solitary enchondroma, which is a single lesion. The presence of soft tissue hemangiomas is characteristic of Maffucci's syndrome. While Ollier's disease does have a higher risk of pathological fracture and malignant transformation compared to solitary enchondromas, the multifocal, often unilateral presentation is the defining diagnostic characteristic.

Question 20

While enchondromas are often asymptomatic, what is the most common cause of pain when it does occur in the absence of malignant transformation?





Explanation

When an enchondroma becomes symptomatic without evidence of malignant transformation, the most common cause of pain is pathological microfractures or small stress fractures through the weakened bone within or surrounding the lesion. These microfractures can be precipitated by minor trauma or repetitive stress. Rapid growth, nerve impingement, or joint effusion are less common causes of pain for an uncomplicated benign enchondroma.

Question 21

Enchondromas in children, especially in the hands and feet, are typically managed with what approach if asymptomatic?





Explanation

Similar to adults, asymptomatic, radiographically benign enchondromas in children are typically managed with observation and serial radiographs. Surgical intervention is usually reserved for symptomatic lesions, those causing deformity, or with suspicious features. The risk of malignant transformation in solitary enchondromas is very low in children.

Question 22

Which imaging modality is generally superior for visualizing the chondroid matrix calcifications within an enchondroma?





Explanation

Computed Tomography (CT) is superior for detecting and characterizing subtle calcifications within a lesion, as well as for evaluating cortical integrity and endosteal scalloping, which are crucial features for evaluating chondroid tumors. While plain X-rays can show obvious calcifications, CT provides much greater detail and eliminates superimposition. MRI is excellent for soft tissue contrast but less sensitive for calcifications.

Question 23

What feature is least suggestive of a benign enchondroma and more concerning for a low-grade chondrosarcoma?





Explanation

Extensive bone destruction and cortical breakthrough with an associated soft tissue mass are definitive signs of an aggressive, malignant process, such as a chondrosarcoma. Benign enchondromas typically have an intact, smooth periosteum, a sharp interface with normal marrow, and do not extend into the soft tissues. A lobulated growth pattern is characteristic of cartilaginous tumors, both benign and malignant.

Question 24

A rare variant of enchondroma that presents as an exophytic lesion mimicking an osteochondroma but composed entirely of cartilage is known as:





Explanation

Enchondroma protuberans is a rare variant of enchondroma that grows exophytically from the bone surface, often mimicking an osteochondroma radiographically, but histologically composed of pure cartilaginous tissue without an overlying bony cap. Periosteal chondromas are also surface lesions, but usually arise from the periosteum itself.

Question 25

A core needle biopsy of a suspicious femoral lesion yields tissue consistent with low-grade chondroid neoplasm, but the pathologist notes cellularity that makes definitive differentiation from enchondroma difficult without further sample. The patient is symptomatic with pain. What is the most appropriate next step?





Explanation

When a core needle biopsy of a symptomatic and suspicious chondroid lesion is inconclusive or equivocal between enchondroma and low-grade chondrosarcoma, obtaining a larger tissue sample is crucial for definitive diagnosis. This is best achieved via an open incisional biopsy (if planning a subsequent definitive resection) or an excisional biopsy if the lesion is small and amenable to complete removal. This provides the pathologist with sufficient material to grade the lesion accurately and guide appropriate treatment. Observation is inappropriate for a symptomatic, suspicious, and equivocal lesion.

Question 26

Patients with enchondromas carrying IDH1/IDH2 mutations are associated with what prognosis?





Explanation

IDH1/IDH2 mutations are frequently found in enchondromas and are recognized as a driver mutation in the development of chondrosarcomas. Therefore, the presence of these mutations in an enchondroma is associated with an increased risk of malignant transformation to a chondrosarcoma. This genetic alteration is a key area of current research into the pathogenesis of chondroid tumors.

Question 27

Beyond enchondromatosis and hemangiomas, what other associated features might be seen in Maffucci's syndrome?





Explanation

Maffucci's syndrome is associated with a range of other malignancies beyond chondrosarcoma, including ovarian granulosa cell tumors, angiosarcomas, pancreatic adenocarcinoma, and brain gliomas. This broad oncogenic risk highlights the complex nature of the syndrome. Café-au-lait spots and Lisch nodules are associated with Neurofibromatosis. Renal cysts and medullary thyroid carcinoma are not typically associated with Maffucci's.

Question 28

For enchondromas in high-risk locations (e.g., long bones in older patients) where differentiation from low-grade chondrosarcoma is challenging, what modification to standard curettage might be considered?





Explanation

In cases where there is a higher suspicion of low-grade chondrosarcoma, or to reduce the risk of recurrence in borderline lesions, extended curettage combined with a local adjuvant therapy (such as cryoablation, phenol, or argon beam coagulation) is often performed. These adjuvants help to destroy any residual microscopic tumor cells in the cavity walls, effectively expanding the margins of the intralesional resection. En bloc resection is typically reserved for higher-grade chondrosarcomas. Radiation and chemotherapy are not standard for low-grade chondrosarcomas or enchondromas.

Question 29

What is the primary utility of a PET scan in the workup of a known enchondroma?





Explanation

PET/CT, using FDG, can be helpful in differentiating benign enchondromas from low-grade chondrosarcomas. Malignant chondroid tumors tend to have higher metabolic activity and will show increased FDG uptake, whereas benign enchondromas typically show little to no uptake. However, there can be overlap, especially with highly active enchondromas or very low-grade chondrosarcomas.

Question 30

An enchondroma in which of the following locations carries the highest risk for pathological fracture?





Explanation

The proximal humerus is a common site for enchondromas and carries a relatively high risk for pathological fracture, especially during falls or sudden stresses. This is due to its long lever arm and the stresses it undergoes during daily activities. While enchondromas are common in the small bones of the hands and feet, pathological fractures there are typically less debilitating, and the overall risk may be higher in the humerus due to the mechanical forces involved.

Question 31

When evaluating for subtle cortical breach or extension into soft tissue in a suspected chondroid tumor, which imaging modality is generally preferred?





Explanation

MRI is superior to CT for assessing soft tissue involvement, marrow invasion, and subtle cortical breach due to its excellent soft tissue contrast resolution. While CT is good for cortical details and calcifications, MRI provides more comprehensive information regarding the extent of the lesion and its relationship to surrounding structures.

Question 32

A patient undergoes curettage for a presumed enchondroma. Intraoperatively, the lesion appears more aggressive than expected. What is the most crucial step regarding the excised tissue?





Explanation

If the intraoperative appearance of a lesion suggests malignancy despite a preoperative diagnosis of enchondroma, an immediate frozen section analysis by an experienced musculoskeletal pathologist is crucial. This rapid assessment can guide the surgeon in extending resection margins or changing the surgical approach during the same procedure, optimizing patient outcomes. Discarding tissue or sending only small fragments would be inappropriate.

Question 33

A young patient presents with multiple cartilaginous lesions in their long bones. Which of the following conditions is least likely to be in the differential diagnosis?





Explanation

Fibrous dysplasia is a fibro-osseous lesion characterized by immature woven bone within a fibrous stroma, often appearing as a 'ground-glass' lesion, not primarily cartilaginous. The other conditions (Ollier's disease, Maffucci's syndrome, multiple osteochondromatosis, and metachondromatosis) all involve multiple cartilaginous lesions or cartilage-capped bony exostoses and would be appropriate differentials.

Question 34

The presence of a periosteal reaction associated with an intramedullary cartilaginous lesion is concerning for:





Explanation

While periosteal reaction can occur with a fracture through an enchondroma, an intact intramedullary cartilaginous lesion exhibiting a periosteal reaction is a significant radiographic red flag for malignancy, specifically a low-grade chondrosarcoma. It suggests cortical irritation or impending cortical breach due to aggressive growth, which is not characteristic of a benign, quiescent enchondroma.

Question 35

Subungual enchondromas are typically found in which location and often cause what clinical symptom?





Explanation

Subungual enchondromas are rare but classically occur in the distal phalanx of fingers or toes, presenting as a slow-growing mass beneath the nail plate. They can cause pressure on the nail matrix, leading to nail dystrophy, deformity (ridging, lifting), and pain.

Question 36

What factor is most strongly correlated with an increased risk of local recurrence after intralesional curettage of an enchondroma?





Explanation

Incomplete removal of the cartilaginous lesion during curettage is the most significant factor contributing to local recurrence of enchondromas. Microscopic remnants of the tumor matrix can regrow and lead to symptomatic recurrence. Other factors like patient age or graft type are less directly linked to recurrence than the completeness of the resection.

Question 37

A 25-year-old male has an incidental 3 cm chondroid lesion in his distal femur, clearly benign on radiographs and MRI. He is asymptomatic. What is the most appropriate next step?





Explanation

For an asymptomatic, radiographically benign enchondroma in a long bone, observation with serial plain radiographs (typically annually for 2-3 years) is appropriate to monitor for any subtle changes in size, cortical integrity, or development of symptoms. Aggressive imaging like annual MRI is generally overkill for a clearly benign lesion, and biopsy or surgery is not indicated in the absence of symptoms or suspicious features.

Question 38

Enchondromas typically originate from rests of cartilage within the metaphysis, but can extend into the diaphysis. This explains their common location in the:





Explanation

Enchondromas are intramedullary cartilaginous tumors believed to arise from displaced rests of growth plate cartilage within the bone. As such, they are classically found in the metaphysis or extend into the diaphysis, thus commonly described as metadiaphyseal lesions. They are not typically epiphyseal (chondroblastoma is) or periosteal.

Question 39

Which of the following statements regarding the growth of a solitary enchondroma is generally true?





Explanation

Benign solitary enchondromas generally stabilize in size or grow very slowly after skeletal maturity. Significant growth in an adult enchondroma is a concerning sign and should prompt further investigation for potential malignant transformation to chondrosarcoma. They are not always present at birth and do not typically grow rapidly like aggressive tumors.

Question 40

A 7-year-old child presents with an asymptomatic solitary lytic lesion in the metaphysis of the distal femur. There are no calcifications. Which of the following is less likely to be the diagnosis compared to an enchondroma, given the absence of calcifications?





Explanation

While some enchondromas can be purely lytic, the classic radiographic feature of an enchondroma is the presence of punctate or rings-and-arcs calcifications within the cartilaginous matrix. In a child, a solitary purely lytic lesion in the metaphysis without calcifications would more commonly suggest diagnoses like a non-ossifying fibroma, unicameral bone cyst, aneurysmal bone cyst, or fibrous cortical defect. Therefore, enchondroma is less likely in this specific scenario due to the absence of its typical calcifications.

Question 41

A 45-year-old female sustains a pathological fracture through a previously undiagnosed enchondroma in her proximal humerus. She undergoes ORIF and the lesion is curetted and grafted. What is the most important aspect of her long-term follow-up?





Explanation

While acute fracture healing is important, the most critical aspect of long-term follow-up for a treated enchondroma (especially one that fractured, which can be an early sign of activity) is surveillance for local recurrence and the rare but potential risk of malignant transformation. This typically involves serial radiographs of the treated area. The patient did not necessarily receive a cancer diagnosis, so that counseling is not indicated.

Question 42

In which of the following scenarios would surgical intervention (e.g., curettage and bone grafting) be most strongly considered for an otherwise asymptomatic enchondroma?





Explanation

Significant cortical thinning, especially when it exceeds 50% of the cortical thickness in a weight-bearing long bone like the distal femur, creates a substantial risk of pathological fracture. Even if asymptomatic, prophylactic curettage and bone grafting would be strongly considered in this scenario to prevent a potentially devastating fracture and to restore structural integrity. The other options describe lesions in less mechanically critical locations or without significant fracture risk.

Question 43

Which of the following clinical presentations most strongly suggests a chondrosarcoma rather than a benign enchondroma?





Explanation

New onset of constant, dull, increasing pain in an intramedullary chondroid lesion, particularly in a large long bone of an older adult, is the most concerning symptom for malignant transformation to chondrosarcoma. Enchondromas are typically asymptomatic unless complicated by fracture. Painless swelling or incidental findings are less specific, and while pathological fractures can occur in benign enchondromas, new, unremitting pain is a more direct indicator of a biologically active, potentially malignant lesion.

Question 44

When using adjuvant cryoablation during extended curettage for chondroid lesions, what is the primary goal?





Explanation

The primary goal of adjuvant therapy like cryoablation (or phenol, argon beam) used during extended curettage is to destroy any microscopic residual tumor cells that may have been left behind in the tumor cavity walls, thereby minimizing the risk of local recurrence. It acts as a local cytotoxic agent to sterilize the tumor bed, particularly in cases where differentiation between benign and low-grade malignant is challenging or in aggressive benign lesions.

Question 45

Why are plain radiographs often sufficient for follow-up of stable, asymptomatic enchondromas?





Explanation

Plain radiographs are cost-effective, readily available, and provide good visualization of the key features relevant to enchondroma follow-up, such as the pattern of matrix calcifications, cortical integrity (e.g., thinning, scalloping), and overall size/stability of the lesion. While not as sensitive for soft tissue or marrow changes as MRI, these are typically not concerns for a stable, asymptomatic enchondroma. They do involve radiation, unlike MRI or ultrasound.

Question 46

A patient presenting with multifocal enchondromas, particularly if unilateral and deforming, should be carefully screened for complications including:





Explanation

Conditions like Ollier's disease (multifocal enchondromatosis) can lead to a variety of complications including limb length discrepancies due to premature or asymmetric growth plate arrest, angular deformities, pathological fractures (due to weakened bone), and a significantly increased risk of malignant transformation to chondrosarcoma. Therefore, screening for all these complications is essential.

Question 47

While sporadic enchondromas are often associated with IDH1/IDH2 mutations, Ollier's disease is frequently linked to somatic mosaic mutations in which gene?





Explanation

Ollier's disease, like solitary enchondromas and central low-grade chondrosarcomas, is strongly associated with somatic mosaic mutations in IDH1 and IDH2 genes. This suggests a common molecular pathway for these cartilaginous tumors, with the mosaicism explaining the multifocal and often unilateral distribution in Ollier's. EXT1/EXT2 mutations are linked to multiple osteochondromatosis.

Question 48

Among benign cartilaginous bone tumors, which of the following is most common to be found as a solitary lesion within the intramedullary cavity?





Explanation

Enchondroma is the most common benign intramedullary cartilaginous tumor. Osteochondroma, while the most common benign bone tumor overall, is an exostosis (surface lesion) rather than intramedullary. Chondroblastoma is a rare benign cartilaginous tumor typically found in the epiphysis. Chondromyxoid fibroma and periosteal chondroma are much rarer than enchondroma.

Question 49

The continued growth of enchondromas in conditions like Ollier's disease after skeletal maturity is believed to be due to:





Explanation

In conditions like Ollier's disease and Maffucci's syndrome, the enchondromas often continue to grow even after skeletal maturity. This is linked to the underlying IDH1/IDH2 mutations, which lead to an accumulation of D-2-hydroxyglutarate (D-2-HG). This oncometabolite disrupts normal chondrocyte differentiation and metabolism, leading to persistent proliferation and impaired apoptosis of the chondrocytes, thereby facilitating continued tumor growth.

Question 50

A 65-year-old patient presents with a several-month history of worsening, dull, persistent pain in their proximal femur. Radiographs show an intramedullary lesion with internal calcifications. What is the most critical next step in their workup?





Explanation

In an older patient with new, worsening pain associated with a chondroid lesion in a large long bone, suspicion for chondrosarcoma is high. An MRI with contrast is the most critical next step. It provides detailed information about the lesion's extent, marrow involvement, cortical integrity, soft tissue extension, and enhancement characteristics, which are crucial for differentiating a benign enchondroma from a low-grade chondrosarcoma. This information then guides the planning of a biopsy and definitive treatment.

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