This 61-year old woman presents with weakness, limited range of motion, and pain of the left shoulder. No history of recent injury is present.
Q1 – With regard to the bone lesion, which of the following findings is present in the MRI study?
(a) Perilesional osseous edema
(b) Rim of sclerosis
(c) Cartilaginous matrix
(d) Pathologic fracture
(e) Endiosteal scalloping
Q2 – Which is the most likely diagnosis of the bone lesion based on the MRI findings?
(a) Giant Cell Tumor (GCT)
(b) Bone infarct
(c) Chondromyxoid fibroma
(d) Breast cancer metastasis
(e) Enchondroma
Q3 – Which of the following statements is false regarding chondral lesions?
(a) Clear cell chondrosarcoma typically involves the end of bone
(b) Cortical scalloping is a supportive finding for chondrosarcoma over enchondroma in the long bones
(c) Chondroblastoma is typically located in the epiphysis of the tubular bones
(d) Enchondroma is usually diaphyseal in location when it involves the short tubular bones
(e) Enchondromas of long tubular bones carry a higher risk of malignant transformation than short tubular bones
Q4 – Which of the following statements is true regarding chondrosarcomas?
(a) The pelvis is an unlikely site for chondrosarcoma
(b) Osteochondromas can transform into chondrosarcoma
(c) Chondrosarcoma is the most common primary malignant bone tumor
(d) Ollier’s disease presents with multiple enchondromas and hemangiomas
(e) Brain is the most common site for chondrosarcoma metastasis
Sagittal T2 FSE Fat Sat
Coronal PD FSE Fat Sat
Axial T2* ADAGE
Coronal T1 FSE
Sagittal T2 FSE Fat Sat
Coronal PD FSE Fat Sat
Axial T2* ADAGE
Coronal T1 FSE
A1 – (c) Cartilaginous matrix. The lesion demonstrates the signal intensity characteristics of the cartilaginous matrix.
(a) is false. Proton density (PD) clearly demonstrates the red marrow low signal (image 4, pink arrow), which disappears on T2. Bone marrow intensity should not be confused with osseous edema. (b), (d) and (e) are also false. Lobulated contours of the lesion are free of a “low signal” sclerotic rim. The lesion mainly demonstrates central position, and there is no cortical scalloping even at the regions where it is intimately close to cortex.
A2 – (e) Enchondroma. An enchondroma has been shown on MRI study.
(a) is false. Giant Cell Tumor (GCT) is a benign, but locally aggressive, osteolytic skeletal neoplasm. They are seen in younger patients (between the ages of 20 and 40; average age is 32). In more than 85% of the cases, GCT abuts articular surface or comes within 1 cm of the articular surface of the long tubular bones. Shoulder region is not a common location for GCTs. They tend to be eccentric and the overlying cortex is thinned, expanded or deficient. The septa are also delicate. GCTs demonstrate T1 low to intermediate solid component with low signal periphery, low signal intensity (variable) on T2, and no cartilage matrix calcification / mineralization. In other words, no high T2 signal “popcorn” appearance or “arcs and whorls type calcification”.
(b) is false. Bone infarcts demonstrate serpiginous peripheral low signal due to granulation tissue and to lesser extent sclerosis on T1. On T2-weighted images hyperintense inner ring of granulation tissue and a hypointense outer ring of sclerosis produces “double line sign.” The central signal is usually isointense to bone marrow (hyperintense T1). Bone infarcts do not demonstrate cartilaginous matrix or arcs and whorls type calcification. T1 hyperintensity is not a characteristic of chondroid lesions. Marked T2 hyperintensity (cartilage matrix) is not a feature of standard infarcts.
(c) is false. Differential diagnosis of enchondroma from chondromyxoid fibroma (CMF) is often difficult. Histologically, CMF consists of myxoid, chondroid, and fibrous elements, and appears very similar to chondrosarcoma. CMF has the same appearance on MRI as other cartilage tumors, which is hypointense on T1 and hyperintense on T2-weighted images. They are often seen as lobulated masses. Diagnostic aids in our case are the patient’s age and the rarity of chondromyxoid fibroma. Our patient is not in the right age group for CMF as patients are usually younger. The majority of CMFs occur in the second and third decades. CMF are extremely rare, accounting for less than 1% of all bone tumors.
(d) is false. There is no history of breast cancer. Breast cancer metastases can be sclerotic or lytic, but do not demonstrate cartilaginous matrix.
A3 – (a) Clear cell chondrosarcoma typically involves the bone end. Flat bone involvement by clear cell chondrosarcoma is unusual. A typical feature of clear cell chondrosarcoma is its predilection for the epiphysis of the long tubular bones unlike predilection to metaphyseal location of conventional intramedullary chondrosarcoma. Clear cell chondrosarcoma involves the proximal end of long tubular bones in 90% of the cases. The differential diagnosis includes chondroblastoma in younger patients due to their location.
(b) is true. Cortical scalloping is a finding supportive of chondrosarcoma over enchondroma in the long bones. Additionally, the depth of endosteal scalloping is considered a valuable distinguishing feature between a long bone enchondroma and chondrosarcoma. Deep (greater than 2/3 of the normal cortical thickness) scalloping is seen in about 90% of chondrosarcomas. This feature may be seen in only 10% of enchondromas.
(c) is true. Chondroblastoma is a benign cartilaginous tumor that occurs in the epiphysis of skeletally immature individuals, between 10-25 years of age. It is more common in patients with open growth plates.
(d) is true. Enchondromas are usually diaphyseal in location when they involve the short tubular bones of the hands and feet (40-65%).
(e) is true. Enchondromas of long tubular bones carry a higher risk of malignant transformation than short tubular bones, although this rule does not apply to Ollier’s or Mafucci’s Diseases or Syndromes.
A4 – (b) Osteochondromas can transform into chondrosarcoma. Both enchondromas and osteochondromas can undergo malignant degeneration to chondrosarcoma.
(a) is false. Although the most common location for conventional intramedullary chondrosarcoma is the long tubular bones (femur followed by proximal humerus), pelvic bones are involved in 25% of the cases. Other bones that can be involved are scapula, ribs and sternum. Spine, craniofacial bones, and sesamoids are less frequent sites for chondrosarcoma.
(c) is false. The most common primary bone malignancy is multiple myeloma, followed by osteosarcoma. Chondrosarcoma follows these two.
(d) is false. Ollier’s disease is known as enchondromatosis, and is not associated with hemangiomas. Mafucci’s syndrome is characterized by multiple enchondromas and hemangiomas, particularly within the hands and feet. Both are associated with increased risk of malignant transformation of enchondromas into chondrosarcoma (5%-30% in Ollier’s disease, and 20% in Maffucci’s).
(e) is false. The brain is NOT a common site for chondrosarcoma metastasis. Most common metastasis sites of chondrosarcoma are lungs, regional lymph nodes and liver.
POMERANZ PEARL #1: You should never confuse with chondromyxoid fibroma, which look more like nonossifying fibroma, are rare and do NOT calcify.
POMERANZ PEARL #2: True chondroid matrix is present in…
Enchondroma: 100%
Chondroblastoma: 50%
Chondromyxoid fibroma: 0%
POMERANZ PEARL #3: Enchondromas MUST have calcification unless or except in phalanges; they NEVER have periostitis; pathologists struggle to differentiate benign from malignant; pain is the BEST way to predict malignant degeneration; they are typically NOT at the bone end unless in phalanges.
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References:
Chakarun CJ, Forrester DM, Gottsegen CJ, et al. Giant cell tumor of bone: review, mimics, and new developments in treatment. Radiographics. 2013 Jan-Feb;33(1):197-211.
Nichols RE, Dixon LB. Radiographic analysis of solitary bone lesions. Radiol Clin North Am. 2011 Nov;49(6):1095-114.
Rajiah P, Ilaslan H, Sundaram M. Imaging of primary malignant bone tumors (nonhematological). Radiol Clin North Am. 2011 Nov;49(6):1135-61.
