Cartilage-Forming Tumors 8/12/2013

Dpt. Aamir Memon

Common Cartilage-Forming Tumors

Cartilaginous neoplasms of bone are characterized by formation of hyaline or myxoid

cartilage.

Classification:

Benign

o Osteochondroma

o Chondroma

o Chondroblastoma

o Chondromyxoid fi broma

Malignant

o Chondrosarcoma

Benign Cartilagenous Tumors

Osteochondroma (Exostosis)

Osteochondroma is a benign bony outgrowth attached to the underlying bone. It is capped by

hyaline cartilage. It is the most frequent benign bone tumor. Multiple osteochondromas occur

in the setting of multiple hereditary exostoses, which is associated with inactivation of EXT

gene and is autosomal dominant in inheritance. Solitary osteochondromas are thought to arise

due to displacement of lateral portion of the growth plate.

Skeletal distribution

Most commonly, it arises from the metaphysis of lower femur, upper tibia, and upper

humerus.

Clinical features:

o Solitary osteochondromas are diagnosed in later life as compared to multiple

osteochondroma, which is usually present in childhood.

o Osteochondromas may be asymptomatic or present with pain and deformity; they

sometimes cause interference with function of regional tendons and blood vessels.

X-ray:

They are metaphyseal in origin and grow in a direction opposite to adjacent joint.

Gross morphology:

Osteochondromas may be sessile or pedunculated, mushroom shaped, with an average size of

4–10 cm.

Microscopy:

o The outermost layer is a fibrous membrane, continuous with the periosteum of the

adjacent bone.

o Under the fibrous membrane is cartilage cap (which is formed by mature hyaline

cartilage).

o Cross section through the lesion demonstrates mature trabecular and cortical bone.

o The cortex of stalk appears to merge with cortex of host bone.

Complications:

o Bursitis (development of bursa around head of a long-standing osteochondroma)

o Formation of osteocartilaginous loose bodies

o Development of secondary chondrosarcoma (incidence of development of secondary

chondrosarcoma in solitary osteochondroma is 1%–2% and is as high as 10% in

multiple lesions).

Chondroma

Chondroma is the most common intraosseous cartilaginous tumor. Based on location, it may

be classified as intramedullary (also known as enchondroma) and subperiosteal or

juxtacortical. It may be solitary or multiple. Multiple enchondromas can manifest as Ollier’s

disease (a rare, nonhereditary disorder characterized by multifocal proliferation of dysplastic

cartilage, also known as enchondromatosis) or as Maffucci syndrome (multiple

enchondromas and soft -tissue hemangiomas).

The risk of malignant transformation, usually to chondrosarcoma, is very high (20%–30%) in

multiple enchondromas. Chondromas mainly occur in bones that develop from enchondral

ossification (they are thought to develop from rests of growth plate cartilage that proliferate

and enlarge).Most lesions are asymptomatic (detected incidentally); may occasionally

manifest with pain or cause pathologicalfracture.

X-ray:

Plain radiograph shows an intramedullary zone of stippled and ring-shaped calcifications.

Enchondroma characteristically involves the acral skeleton (small bones of the hands and

feet) and the long bones (such as femur, humerus, tibia, fibula, radius, and ulna). In the long

bones, the tumor is found in metaphyses and proximal/distal diaphyses.

Gross morphology:

They are usually smaller than 3 cm, gray– blue, and translucent.

Microscopy:

o Sections show well-circumscribed nodules of hyaline cartilage.

o Chondrocytes in the lacunae are cytologically benign.

o Cartilage in periphery of nodules undergoes enchondral ossification and the center

frequently calcifies and dies.

Chondroblastoma

Clinical features:

Chondroblastoma is a rare tumor seen in children and adolescents with open growth plates;

most commonly in males less than 20 years. It is intramedullary in location and commonly

involves the epiphyseal ends of femur, humerus, and tibia, and small bones of hands and

feet. Presents with pain, restricted mobility, and joint effusion (because of proximity to the

joint).

X-ray:

Typical radiological presentation is that of a well-defined lytic lesion surrounded by

sclerosis. Spotty calcification is common. Cysts are present about 20% of the time, and both

MRI and CT can define fluid levels.

Gross morphology:

On gross examination, chondroblastoma has a lobulated, round form, and is made up of

friable, soft, grayish-pink tissue that may be gritty.

Microscopy:

Chondroblastoma is extremely cellular and is comprised of closely packed clusters of

tumor cells.

The basic tumor cell is an embryonic chondroblast, a polyhedral cell with a

sharply-defined cell membrane, and lobulated nuclei showing longitudinal

grooves (coffee-bean appearance), without sufficient differentiation to produce

intercellular chondroid.

Mitoses and necrosis are frequently observed.

Scant amount of lace-like hyaline matrix may be laid down, which calcifies to

produce a characteristic chicken-wire calcification.

Scattered osteoclastic giant cells may be seen.

Treatment:

Curettage or surgical excision is the treatment of choice. Due to the risk of recurrence and

associated functional loss, the initial curettage should be as meticulous as necessary to ensure

complete removal of the lesion.

Prognosis:

It is locally invasive; rarely metastasizes to lungs; recurrences are common

Chondromyxoid Fibroma (CMF) Clinical features:

Affects young adults and presents with localized dull aching pain and swelling in the affected

region.

X-ray:

Seen as a large, lobulated, sharply-defined, eccentric lytic lesion, surrounded by a rim of

sclerosis in the metaphysic of long bones.

Gross:

o Average size is 3–8 cm.

o Cut surface is solid, glistening, and tan–gray.

Microscopy:

o The predominant features of CMF are the zonal architecture and lobular pattern.

o Hypocellular lobules of poorly formed hyaline cartilage and myxoid tissue are

separated by fibrous septae.

o Nodules of cartilage are found in between fibromyxoid areas.

o The chondrocytes in myxoid areas are plump-to-spindled in shape and have indistinct

cell borders.

o Varying degree of cytological atypia may be seen.

o Small foci of calcification may be observed.

Treatment and prognosis:

Treatment of CMF is en bloc excision.

Recurrences after curettage are common.

Malignant Tumors

Chondrosarcoma

Chondrosarcoma is a malignant mesenchymal tumor that produces cartilage matrix. There are

several subtypes of chondrosarcoma, which vary in terms of location, appearance, treatment,

and prognosis.

Classification:

Primary chondrosarcoma is very uncommon, arises centrally in the bone, and is found in

children.

Secondary chondrosarcoma arises from benign cartilage defects such as osteochondroma or

enchondroma.

Chondrosarcoma can also be classified as intramedullary, which generally arises from an

enchondroma, and surface which arises from a pre-existing osteochondroma.

Chondrosarcoma can also be classified based on:

Topography

Conventional intramedullary (central) chondrosarcoma

- Arises from medullary cavity of long bones, pelvis, costochondral junction of ribs, and

shoulders

X-ray shows a lytic lesion with blotchy calcification

Causes fusiform thickening of shaft and perforation of cortex

May arise de novo (80%–90%) or in a pre-existing osteochondroma (10%–20%)

o Juxtacortical (peripheral) chondrosarcoma: Arises in the shaft of a long bone.

o Morphology

o Conventional (which is further subtyped as hyaline or myxoid)

o Clear cell

o Dedifferentiated

o Mesenchymal

Signs of malignancy in an osteochondroma:

o Rapid growth; size more than 8 cm

o Cartilaginous cap more than 3-cm thick

o X-ray showing irregular margins of the cartilage cap

Gross Morphology:

o On gross examination, chondrosarcoma is a gray–white, lobulated, bulky,

translucent mass with a gelatinous consistency.

o Erosion/destruction of cortex is frequent.

o Calcification and ossification may be seen.

Microscopy:

o Histologically, chondrosarcoma is comprised of invasive lobules of anaplastic

cartilage. It is differentiated from benign cartilaginous tumors based on presence

of two or more cells per lacuna, binucleated cells, enlarged plump, and

hyperchromatic nuclei and nuclear pleomorphism.

o Abundant mitoses and enchondral ossification is seen (to be differentiated from

osteosarcoma in which the osteogenesis is directly from malignant mesenchymal

cells).

o Chondrosarcoma is classified into Grades I, II, and III, based on cellularity,

pleomorphism, mitoses, and necrosis.

Prognostic factors:

o Size more than 10 cm is associated with bad prognosis.

o Tumor–X-ray correlation is a must (more radiolucent the tumor, higher the grade,

and worse the prognosis).

Treatment and prognosis:

Treatment of chondrosarcoma is wide surgical excision. There is a very limited role for

chemotherapy or radiation.