WBR0749

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
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 of 8 months duration. The patient describes the pain as aching feeling that is worse at night. It is not relieved by any position or rest. However, the pain is dramatically relieved by aspirin. Vital signs show a temperature of 37.2 degrees C (99 degrees C), a heart rate of 88 bpm, and a blood pressure measuring 116/74 mmHg. Physical examination is remarkable for proximal right femoral tenderness with muscle atrophy and muscle weakness in the same region. Pathological analysis of the lesion shows an osteolytic radiopaque zone of dense homogenous sclerosis of the bone surrounding a rim around 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 commonly of the proximal femur, tibia, or spine. It is an independent growth within bone. Patients typically have signs and symptoms consistent with the patient in the vignette.
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, or 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 hisopathological 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 painful lesion in the proximal femoral area (most common), or the tibia, or 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. The pathological findings may still be necessary in some cases. Osteoid osteoma is characterized by 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 in adolescent males as a painful lesion in the proximal femur with dramatic relief to aspirin. Osteoid osteoma has pathological features of independent neoplasm surrounded by bone tissue. Reference: 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. Educational Objective: References: ]]
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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