WBR0474
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Musculoskeletal/Rheumatology |
| Prompt | [[Prompt::A 12 year old boy is brought by his mother to the physician's clinic for multiple bone fractures and abnormal facial bone. Lab work-up reveals no abnormality. After further imaging and genetic testing, the diagnosis is made. The physician explains to the mother that her child's condition is caused by primary spongiosa filling the medullary cavity and causing an "Erlenmeyer flask" bones on xray. Which of the following the most likely diagnosis?]] |
| Answer A | AnswerA::Osteoporosis |
| Answer A Explanation | AnswerAExp::Osteoporosis is characterized by 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 with mosaic bone pattern that cause long bone chalk-stick fractures. |
| Answer D | AnswerD::Osteomalacia |
| Answer D Explanation | AnswerDExp::Osteomalacia is characterized by 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) is a disease that is characterized by failure of nromal bone resorption. It causes thickening of bones that become dense but more predisposed to fractures. On xray, "Erlenmeyer flask" appearance of bones is characteristic. Osteopetrosis is further described as primary spongiosa filling the medullary cavity. However, the diagnosis may be missed by lab work-up because serum values of calcium, phosphage, and ALP are typically within normal limits.
The primary defect in osteopetrosis is believed to be 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. Educational Objective:
Osteopetrosis is characterized by failure of normal bone resorption due to defect of osteoclasts. In osteopetrosis, primary spongiosa fills the medullary cavity. Lab values are usually within normal limits. Xray often shows visible "Erlenmeyer flask" bones. |
| Approved | Approved::No |
| Keyword | WBRKeyword::osteopetrosis, WBRKeyword::marble, WBRKeyword::bone, WBRKeyword::disease, WBRKeyword::marble bone disease, WBRKeyword::calcium, WBRKeyword::phosphate, WBRKeyword::ALP, WBRKeyword::alkaline, WBRKeyword::phosphatase, WBRKeyword::alkaline phosphatase, WBRKeyword::osteoclast, WBRKeyword::defect, WBRKeyword::bone, WBRKeyword::marrow, WBRKeyword::transplantation, WBRKeyword::bone marrow transplantation, WBRKeyword::BMT, WBRKeyword::spongiosa, WBRKeyword::medullary, WBRKeyword::cavity, WBRKeyword::flask, WBRKeyword::erlenmeyer, WBRKeyword::xray |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |