Mr. Raghav, 17-yrs-old man presents with nocturnal pain in the bone of his left leg. He relates that the pain is quickly relieved by taking aspirin. X-rays reveal a round, radiolucent area with central mineralization that is surrounded by thickened bone. The lesion measures approximately 1.2 cm in diameter. Which of the following is the most likely diagnosis? (AIIMS May 2012)
a. Many benign tumors of bone are capable of producing either bone or cartilage.
b. Bone-producing tumors include osteomas, osteoid osteomas (OOs), and osteoblastomas.
c. OOs are bone tumors that are typically found in the cortex of the metaphysis.
d. OOs occurs predominantly in children or young adults in the second and third decades of life as a benign osteoblastic (bone forming) lesion of small size, which by definition is less than 3 cm.
e. In OO malignant change does not occur, unlike the case for the closely related but larger osteoblastoma, in which there is occasional malignant change.
f. OOs are often located in the diaphyseal cortex of the tibia or femur, unlike osteoblastomas, which occur in the spine (vertebral arch) or medulla of long bones.
g. OOs are characteristically painful because of the excess pro duction of prostaglandin E.
h. The pain occurs at night and is promptly relieved by aspirin.
i. X-rays typically reveal a radiolucent area (the tumor itself) surrounded by thickened (reactive) bone.
j. Histologic sections reveal an oval mass, the central nidus of which consists of interconnected trabeculae of woven bone containing numerous osteoblasts and uncalcified osteoid.
k. This central nidus is surrounded by a rim of sclerotic bone. Treatment is complete excision of the nidus to prevent recurrence.
l. A histologic picture that is identical to the central nidus of an osteoid osteoma is seen with the osteoblastoma. Osteoblastomas are sometimes called giant osteoid osteomas.
m. They differ from OOs by their larger size (greater than 2 cm) and lack of a decreased pain response to aspirin.
n. Osteoblastomas also lack the surrounding sclerotic bone formation of OOs and are found in the medulla of bone rather than the cortex.
o. Osteomas are usually solitary and clinically silent.
p. They may be multiple in patients with Gardner’s syndrome (familial colonic adenomatous polyposis with mesenchymal lesions).
q. Osteomas are composed of a circumscribed mass of dense sclerotic bone and are typically found in flat bones, such as the skull and facial bones.