WBR0474
| Author | [[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Musculoskeletal/Rheumatology |
| Prompt | [[Prompt::A 12-year-old male is brought by his mother to the physician's office for multiple bone fractures. While lab work-up reveals no abnormality, following further imaging and genetic testing, you diagnose the patient with a condition caused by primary spongiosa filling the medullary cavity, manifesting with "Erlenmeyer flask" bones on x-ray. Which of the following diagnoses most likely applies to this patient?]] |
| Answer A | AnswerA::Osteoporosis |
| Answer A Explanation | AnswerAExp::Osteoporosis is characterized by the loss of interconnections of trabeculated bone. |
| Answer B | AnswerB::Osteopetrosis |
| Answer B Explanation | [[AnswerBExp::Osteopetrosis is characterized by primary spongiosa filling the medullary cavity.]] |
| Answer C | AnswerC::Paget's disease |
| Answer C Explanation | [[AnswerCExp::Paget's disease is characterized by abnormal bone architecture, manifesting as a mosaic bone pattern, resulting in long bone chalk-stick fractures.]] |
| Answer D | AnswerD::Osteomalacia |
| Answer D Explanation | [[AnswerDExp::Osteomalacia is characterized by the defective mineralization or calcification of osteoid.]] |
| Answer E | AnswerE::Polyostotic fibrous dysplasia |
| Answer E Explanation | [[AnswerEExp::Polyostotic fibrous dysplasia is characterized by the replacement of bone by fibroblasts, colalgen, and irregular bone trabeculae.]] |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::Osteopetrosis (marble bone disease), a disease characterized anormal bone resorption, causes thickening of bones that become dense and predisposed to fractures. An "Erlenmeyer flask" appearance of bones is characteristic upon x-ray. Osteopetrosis results from primary spongiosa filling the medullary cavity, but the diagnosis may be overlooked by lab work-up because serum values of calcium, phosphage, and ALP are typically within normal limits.
The primary defect in osteopetrosis is due to abnormal functioning of osteoclasts, which are derived from monocyte lineage. As a result, bone marrow transplantation (BMT) is thought to be the only appropriate cure for patients with osteopetrosis. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::osteopetrosis, WBRKeyword::bone, WBRKeyword::marble bone disease, WBRKeyword::calcium, WBRKeyword::phosphate, WBRKeyword::ALP, WBRKeyword::alkaline phosphatase, WBRKeyword::osteoclast, WBRKeyword::bone marrow transplantation, WBRKeyword::BMT, WBRKeyword::spongiosa, WBRKeyword::medullary cavity, WBRKeyword::skeletal, WBRKeyword::formation abnormality, WBRKeyword::x-ray |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |