Question 151
A 16-year-old boy has noted pain in his left knee after each hockey practice session for the past month. On examination there is tenderness to palpation of his left knee, with reduced range of motion. A plain film radiograph of the left leg reveals a mass of the proximal tibial metaphysis that erodes the bone cortex, lifting up the periosteum where reactive new bone is apparent. The mass does not extend into the epiphyseal region. A bone biopsy is performed and microscopic examination shows atypical, elongated cells with hyperchromatic nuclei in an osteoid stroma. Which of the following neoplasms is he most likely to have?
A Ewing sarcoma
B Osteosarcoma
C Chondrosarcoma
D Multiple myeloma
E Metastatic seminoma
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(B) CORRECT. Osteoid production is characteristic for osteosarcoma. The location about the knee is common. Most arise in the metaphyseal region. Overall, malignancies are uncommon in children, but bone tumors are one of the most common malignancies at this age.
(A) Incorrect. Ewing sarcoma has a peak incidence at a younger age. It most often involves the diaphyseal region. It does not produce osteoid.
(C) Incorrect. Chondrosarcomas do not make osteoid. They can occur overa wide age range.
(D) Incorrect. Myelomas are seen in older adults and produce lytic bone lesions filled with plasma cells.
(E) Incorrect. Metastases are unlikely to occur at this age. Overall, metastases are the most common malignancy involving bone. Primary bone tumors are not common.
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Question 152
A 53-year-old man has noted a slowly enlarging "bump" on his left elbow for the past 2 years. On physical examination there is a 2 cm firm, non-tender mass over the left olecranon process. The mass is excised and on sectioning has a chalky white consistency. Microscopically, the mass is composed of elongated, needle-shaped crystals that under polarized light are negatively birefringent. Surrounding the crystals is a granulomatous inflammatory infiltrate. Which of the following laboratory test findings is he most likely to have?
A Hyperuricemia
B Hyperglycemia
C Elevated rheumatoid factor
D Hypercholesterolemia
E Increased serum creatinine
F Hypercalcemia
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(A) CORRECT. Gouty tophi can develop with gout. He has increased deposition of sodium urate crystals in the soft tissue around a joint. Most patients with an increased serum uric acid do not have a gouty arthritis, though some do.
(B) Incorrect. Gout is unrelated to diabetes mellitus.
(C) Incorrect. Persons with rheumatoid arthritis may have rheumatoid nodules in a similar location, and they are a form of granuloma, but there is no deposition of sodium urate crystals with rheumatoid arthritis.
(D) Incorrect. Gouty tophi are not related to cholesterol metabolism.
(E) Incorrect. An increased serum creatinine may occur with renal failure, and gout may cause renal failure, but the presence of gouty tophi is more likely related to deranged uric acid metabolism.
(F) Incorrect. An increased serum calcium could rarely lead to metastatic calcification, which may occur in lung, stomach, and kidney, but not as large deposits.
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Question 153
A 5-year-old boy measures than the 5th percentile in height for age. On physical examination most of his decreased height is due to very short legs. However, his trunk and head appear normally proportioned for age. He is of above average intelligence and becomes an orthopedic surgeon. His parents and relatives are not affected by this disorder. Which of the following is the most likely diagnosis?
A Fibrous dysplasia
B Osteogenesis imperfecta
C Ollier disease
D Alport syndrome
E Achondroplasia
F Thanatophoric dysplasia
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(E) CORRECT. This is the most common form of short-limbed dwarfism. Though it has an autosomal dominant inheritance pattern, about half of cases represent new mutations, and there is no family history. Heterozygotes have normal longevity, while homozygotes usually die soon after birth.
(A) Incorrect. Fibrous dysplasia can be seen with McCune-Albright syndrome.
(B) Incorrect. Osteogenesis imperfecta leads to multiple fractures. There are several forms.
(C) Incorrect. Ollier disease is associated with enchondromatosis.
(D) Incorrect. Alport syndrome is associated with renal failure and deafness.
(F) Incorrect. Thanatophoric dysplasia is a form of short-limbed dwarfism that is lethal in utero or shortly after birth.
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Question 154
A 38-year-old woman has severe systemic lupus erythematosus with renal complications. She is treated with long-term corticosteroid therapy. Which of the following bone diseases is she most likely to develop?
A Paget disease of bone
B Rickets
C Osteochondritis
D Osteoporosis
E Osteomalacia
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(D) CORRECT. Osteoporosis is one of the complications of long-term therapy with corticosteroids.
(A) Incorrect. Paget disease of bone is not related to corticosteroid therapy.
(B) Incorrect. Rickets is due to a deficiency of vitamin D in children with growing bones.
(C) Incorrect. Osteochondritis is an inflammatory process. Corticosteroids reduce inflammation.
(E) Incorrect. This is due to vitamin D deficiency in adults.
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Question 155
A 15-year-old girl is noted to have an odd, twisted appearance to her back while she is out swimming with her friends. She is tall and thin. A radiograph reveals an abnormal lateral bowing of the spine, with 20 degrees of lateral curvature in the mid-thoracic region. Which of the following is most likely to produce these findings?
A Asymmetric cartilage growth of vertebral body end plates
B Multiple osteochondromas of the vertebral bodies
C Vitamin D deficiency with rickets
D A disorder of procollagen synthesis with multiple compressed fractures
E Trauma
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(A) CORRECT. She has scoliosis, which is an idiopathic, but not uncommon, condition that has a female predominance.
(B) Incorrect. Osteochondromatosis is rare and is seen mostly in males. The extremities are affected most, and dwarfism results in severe cases.
(C) Incorrect. The bony deformities of rickets would not likely be asymmetric.
(D) Incorrect. She does not have osteogenesis imperfecta, which is associated with multiple fractures, particularly of long bones.
(E) Incorrect. Trauma may lead to bone deformities, but not typically of the spine with lateral curvature.
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Question 156
A 23-year-old man notes some minor discomfort over the lateral aspect of his right knee after a day working in a cramped cubicle (because IT put the 'desktop' workstation on the floor). On physical examination he has a palpable "bump" in this region. A radiograph of the knee reveals a lateral bony projection from the lower femoral metaphysis. There is no adjacent soft tissue swelling. The lesion is excised and is composed of a 3 cm stalk of bony cortex capped by cartilage. Which of the following is the most likely diagnosis?
A Osteochondroma
B Giant cell tumor
C Aneurysmal bone cyst
D Osteoid osteoma
E Enchondroma
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(A) CORRECT. Osteochcondromas are not true neoplasms but an exaggeration of the growth plate. They are benign and slow-growing. They may cause discomfort because they project outward from the bone.
(B) Incorrect. These tumors expand the bone outward.
(C) Incorrect. These are located in the metaphysis and are expansile lesions.
(D) Incorrect. These are located within the bone. A small nidus is surrounded by sclerotic bone.
(E) Incorrect. These are located within bone.
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Question 157
A 75-year-old man has complained of lower back pain for 8 years. As part of a workup for a persistently elevated lymphocytosis, he has a right posterior iliac crest marrow biopsy performed. On microscopic examination hematopoiesis is normal, but the bone spicules are thickened with irregular cement lines forming a mosaic appearance with both increased osteoblastic and osteoclastic activity. Which of the following conditions is most likely to occur in conjunction with his underlying disease process?
A Dementia
B Myelofibrosis
C Hepatic cirrhosis
D Chronic renal failure
E Congestive heart failure
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(E) CORRECT. He has Paget disease of bone, and he has the classic phase of mixed osteolysis and osteogenesis. The increased blood flow into the involved areas of bone can lead to high output congestive heart failure in older persons with minimal cardiac reserve. Paget disease of bone is most often seen in older Caucasians.
(A) Incorrect. Bone diseases are not associated with dementias.
(B) Incorrect. The involvement of Paget disease of bone, even if polyostotic, is not extensive enough to affect hematopoiesis.
(C) Incorrect. Paget disease of bone does not affect the liver.
(D) Incorrect. The biochemical abnormalities of Paget disease of bone are subtle and not likely to affect renal function.
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Question 158
Bone densitometry performed on a 42-year-old woman shows her bone mass decreased more than 2 standard deviations below the mean for age in her left femoral head, wrist, and lumbar vertebral region. Six months later, the amount of bone loss is seen to be increased by repeat densitometry examination. These findings are most likely to be associated with which of the following serum laboratory test abnormalities:
A Parathormone of 5 pg/mL
B Cortisol of 75 microgm/dL
C Total immunoglobulin of 3.5 g/dL
D Uric acid of 15.7 mg/dL
E Total cholesterol of 514 mg/dL
F Alkaline phosphatase of 238 U/L
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(B) CORRECT. She has osteoporosis with decreased bone mass. Most cases do not have a specific etiology, but Cushing syndrome with hypercortisolism can promote osteoporosis. Her age should make you suspicious, since she is not likely to be postmenopausal.
(A) Incorrect. Hypoparathyroidism is not going to accelerate bone loss. The bone resorption that accompanies hyperparathyroidism can cause osteoporosis. Over 95% of cases of osteoporosis are 'primary' with unknown cause.
(C) Incorrect. This elevation in serum globulin should make you suspect a monoclonal gammopathy, but myeloma leads to focal bone lytic lesions.
(D) Incorrect. Hyperuricemia can be associated with gout that can cause focal bone destrution near affected joints, the bone mass overall is not decreased.
(E) Incorrect. Hypercholesterolemia is associated with accelerated atherosclerosis which does not affect bone mass.
(F) Incorrect. She is not likely to have an increased alkaline phosphatase, even though her bone loss is accelerated.
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Question 159
A 30-year-old healthy man has experienced headaches for the past month. On physical examination there are no abnormal findings. Laboratory studies show a serum calcium of 12.2 mg/dL with phosphorus of 2.5 mg/dL and albumin of 4.3 g/dL. Which of the following bone lesions is most frequently associated with these findings?
A Osteochondroma
B Giant cell tumor
C Paget disease of bone
D Osteitis fibrosa cystica
E Fibrous dysplasia
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(D) CORRECT. This lesion is filled with osteoclasts and can have a cystic appearance on radiography. In some cases the osteoclast proliferation is so florid that a 'brown tumor' is formed. There is an association with hyperparathyroidism. Persons with hyperparathyroidism may feel well, but may also have headaches, bone pain, or abdominal pain.
(A) Incorrect. This lateral projection from the cortex is not associated with disorders of calcium metabolism.
(B) Incorrect. The appearance of this neoplasm is not related to hyperparathyroidism.
(C) Incorrect. Paget disease of bone is not related to calcium metabolism or parathyroid function.
(E) Incorrect. Fibrous dysplasia does not result from hyperparathyroidism.
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Question 160
During the past year a 22-year-old man begins to note persistent lower back pain and stiffness that diminishes with activity. Within the next 10 years he develops hip and shoulder pain with decreased range of motion. On physical examination at age 42 he has diminished lumbar lordosis with decreased lumbar spine mobility. He has no other major medical problems. Which of the following is the most likely diagnosis?
A Rheumatoid arthritis
B Ankylosing spondylitis
C Osteoarthritis
D Lyme disease
E Calcium pyrophosphate dihydrate deposition disease
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(B) CORRECT. He probably is also HLA B27 positive. The earlier in life the disease begins, the worse the prognosis. There is a progressive bony ankylosis, especially of sacroiliac joints and spine.
(A) Incorrect. RA typically involves small joints.
(C) Incorrect. Osteoarthritis typically involves a single large joint.
(D) Incorrect. However, the third stage of Lyme disease can have intermittent attacks of arthritis involving large joints, particularly knee, with swelling.
(E) Incorrect. 'Pseudogout' is more typical of the elderly and occurs in acute attacks.
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