WBR0749

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Musculoskeletal/Rheumatology, SubCategory::Oncology
Prompt	[[Prompt::A 16-year-old boy is brought by his mother to the physician's office for a painful lesion in his right thigh. The patient describes the pain started 8 months ago. It is an aching feeling that is worse at night. The pain is not relieved by any position or even at rest. However, the pain is dramatically relieved by aspirin. His blood pressure is 116/74 mmHg, his heart rate is 88/min, and his temperature is 37.2 °C (99 °F). Physical examination is remarkable for proximal right femoral tenderness with muscle atrophy, and muscle weakness in the same region. Imaging of the lower extremity reveals a radiopaque osteolytic zone of dense homogenous bony sclerosis surrounding a central nidus. What is the most likely diagnosis of the patient's condition?]]
Answer A	AnswerA::Giant cell tumor
Answer A Explanation	[[AnswerAExp::Giant cell tumor presents commonly in early adulthood at the epiphyseal end of long bones. It is a benign tumor with local aggressive features. Xray shows a "double-bubble" sign. On pathology, it is characterized by spindle-shaped cells with multinucleated giant cells, hence its name.]]
Answer B	AnswerB::Osteosarcoma
Answer B Explanation	[[AnswerBExp::Osteosarcoma affects adolescent males most commonly. It is associated with Paget's disease of the bone. It usually affects the metaphysis of long bones, such as the distal femur or the proximal tibia. On xray, it is characterized by "Codman triangle".]]
Answer C	AnswerC::Osteoid osteoma
Answer C Explanation	[[AnswerCExp::Osteoid osteoma is a benign neoplasm that commonly appears in the proximal femur, tibia, or spine. It is an independent growth within bone. Patients typically complain of a painful lesion in the proximal femur report dramatic relief with aspirin administration. Imaging of lesions reveals an osteolytic radiopaque zone of dense homogenous bony sclerosis surrounding a central nidus.]]
Answer D	AnswerD::Chondrosarcoma
Answer D Explanation	AnswerDExp::Chondrosarcoma is a malignant tumor among middle-aged patients. It is usually located in the pelvis, spine, scapula, humerus, tibia, or even femur. Pathologically, it shows mass within the medullary cavity.
Answer E	AnswerE::Ewing's sarcoma
Answer E Explanation	[[AnswerEExp::Ewing's sarcoma is a common bone tumor of childhood. It appears in the diaphysis of long bones, in the pelvis, or scapula. On pathology, the tumor appears as small blue cells of malignant features with onion-skin appearance in bone. It is caused by a t(11,22) translocation.]]
Right Answer	RightAnswer::C
Explanation	[[Explanation::The patient presents with clinical and radiological features typical of osteoid osteoma. The disease is often diagnosed based on findings during history-taking and physical examination when a high index of suspicion is present. Typically, patients are adolescent males, presenting with a painful lesion in the proximal femoral area (most common), the tibia, the spine, or even the hands. One classical finding is the reported dramatic relief to aspirin and other NSAIDs, which sometimes may be diagnostic of the disease, but pathological findings may still be necessary. Imaging of osteoid osteoma usually reveals Osteoid osteoma shows a well-circumscribed neoplasm independent of bone around it with growth of osteoid tissue within it. Educational Objective: Osteoid osteoma is a neoplasm of the bone, most commonly presenting among adolescent males as a painful lesion in the proximal femur with dramatic relief upon aspirin administration. Imaging of lesions reveals an osteolytic radiopaque zone of dense homogenous bony sclerosis surrounding a central nidus. References: Cohen MD, Harrington TM, Ginsburg WW. Osteoid osteoma: 95 cases and a review of the literature. Seminars in Arthritis and Rheumatism. 1983;12(3):265-281.]]
Approved	Approved::No
Keyword	WBRKeyword::osteoid, WBRKeyword::osteoma, WBRKeyword::sarcoma, WBRKeyword::bone, WBRKeyword::bony, WBRKeyword::tumor, WBRKeyword::cancer, WBRKeyword::ewing's, WBRKeyword::sarcoma, WBRKeyword::chondrosarcoma, WBRKeyword::osteosarcoma, WBRKeyword::aspirin, WBRKeyword::relief, WBRKeyword::relieved
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