Biology, Genetics & Bone Healing MCQs

An infant presents with failure to thrive, hepatosplenomegaly, and recurrent severe infections. Radiographs exhibit a diffuse "bone-within-bone" appearance.

What is the definitive curative treatment for the underlying etiology of this patient's disorder?

A 68-year-old female with Paget's disease of the tibia requires a corrective osteotomy for severe bowing.

To minimize intraoperative bleeding, a specific medication is administered two months preoperatively. What is the mechanism of action of the most appropriate drug for this indication?

A bone biopsy from a 30-year-old male with recurrent fractures demonstrates islands of calcified cartilage retained within mature trabecular bone and a lack of proper marrow spaces. What cellular ultrastructural feature is typically absent or dysfunctional in the cell line responsible for this pathology?

A 75-year-old man presents with an increasing hat size and progressive sensorineural hearing loss. His serum calcium and phosphorus are within normal limits. Which combination of laboratory markers is most likely to be elevated, reflecting the hypermetabolic state of his bone disease?

A family cluster presents with craniofacial dimorphism, thin nails, sparse hair, and severe early-onset hip osteoarthritis. Genetic analysis reveals a deletion on chromosome 8q23.3. Which of the following genes is mutated in this condition?

A 4-year-old child presents with dense, brittle bones on radiography, bilateral optic nerve atrophy, and renal tubular acidosis. What specific enzyme deficiency links these three clinical findings?

A 12-year-old boy presents with bilateral shoulder hypermobility, allowing him to touch his shoulders in the midline. Radiographs reveal partial absence of the clavicles and multiple wormian bones in the skull. Which gene mutation is most likely responsible for this condition?

A 12-year-old boy presents with delayed eruption of permanent teeth and the ability to approximate his shoulders anteriorly. Radiographs reveal bilateral absence of the clavicles and patent cranial sutures. Which gene mutation is most likely responsible for this condition?

A patient is incidentally found to have multiple small, well-defined, circular radiopaque spots (3-10 mm) clustered in the periarticular regions of the pelvis and long bones. The patient is asymptomatic. What is the most appropriate next step in management?

Camurati-Engelmann Disease (Progressive Diaphyseal Dysplasia) is characterized by which of the following clinical and radiographic features?

A 30-year-old man complains of progressively worsening deep bone pain and joint contractures in his right leg. Radiographs display dense, eccentric, undulating cortical hyperostosis along the femur and tibia, classically described as resembling "flowing candle wax." Which gene mutation is primarily associated with this sporadic localized dysplasia?

A 2-week-old infant is diagnosed with bilateral radial agenesis. Unlike many other syndromes with radial deficiencies, the infant has perfectly normal thumbs on both hands. Blood work reveals severe thrombocytopenia. Which of the following best describes the inheritance pattern and implicated gene for this condition?

A 15-year-old girl is incidentally found to have an expansive, radiolucent, 'ground-glass' lesion in the proximal femur with endosteal scalloping. An incisional biopsy is performed. What is the classic histopathological hallmark of this localized skeletal condition?

A 3-year-old child presents with a history of recurrent, painful soft tissue swellings in the neck and back that eventually harden. On physical examination, there is noticeable shortening and valgus deviation of the bilateral great toes. Which of the following gene mutations is the primary cause of this condition?

A 35-year-old man presents with progressive joint stiffness and localized pain in his right lower extremity. Radiographs reveal unilateral, undulating cortical hyperostosis along the medial aspect of the femur and tibia, resembling "dripping candle wax." What is the underlying genetic mutation associated with this specific radiologic finding?

A 4-year-old boy presents with disproportionate focal enlargement of his right index and middle fingers, noticeable since birth. The overgrowth is prominent on the volar aspect, causing dorsal deviation, and MRI reveals substantial fibrofatty infiltration along the median nerve territory. Which signaling pathway is typically altered in this focal overgrowth condition?

In distraction osteogenesis using an Ilizarov circular frame, which of the following histologic processes is primarily responsible for the formation of new bone in the distraction gap under ideal conditions of stability and rate?

A 22-year-old male presents with chronic, mild knee pain. Radiographs reveal an eccentric, sharply circumscribed, osteolytic lesion with a sclerotic rim in the proximal tibial metaphysis.

What is the most characteristic histological finding for this lesion?

In a patient with confirmed Camurati-Engelmann disease experiencing significant, debilitating bone pain, what is the most effective first-line medical therapy?

Which of the following histological features is most useful in differentiating a Chondroblastoma from a Chondromyxoid fibroma?