Question 141
An otherwise healthy 44-year-old man with no prior medical history has had increasing back pain and right hip pain for the past decade. The pain is worse at the end of the day. On physical examination he has bony enlargement of the distal interphalangeal joints. A radiograph of the spine reveals the presence of prominent osteophytes involving the vertebral bodies. There is sclerosis with narrowing of the joint space at the right acetabulum seen on a radiograph of the pelvis. Which of the following diseases is he most likely to have?
A Gout
B Rheumatoid arthritis
C Osteoarthritis
D Osteomyelitis
E Lyme disease
F Pseudogout
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(C) CORRECT. Degenerative osteoarthritis is a common and progressive condition that becomes more frequent and symptomatic with aging. There is erosion and loss of articular cartilage with joint space narrowing. There is minimal inflammation.
(A) Incorrect. A gouty arthritis is more likely to be accompanied by swelling, and deformity with joint destruction. The pain is not related to usage.
(B) Incorrect. Rheumatoid arthritis typically involves small joints of the hands and feet most severely, and there is a destructive pannus that leads to marked joint deformity.
(D) Incorrect. Osteomyelitis represents an ongoing infection that produces marked bone deformity, not just joint narrowing.
(E) Incorrect. Lyme disease produces a chronic arthritis, but it is typically preceded by a deer tick bite with a skin lesion. It is much less common than osteoarthritis.
(F) Incorrect. Pseudogout, or calcium pyrophosphate dihydrate deposition disease, is more often a disease of the elderly, accompanied by meniscal calcification and joint space narrowing. There can be acute attacks with marked pain. The knees are most often involved.
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Question 142
An 80-year-old woman has had no major medical problems, but she has never been physically active for most of her life. One day she falls out of bed and immediately notes a sharp pain in her left hip. She is subsequently unable to ambulate without severe pain. Radiographs show not only a fracture of the left femoral head, but also a compressed fracture of T10. Which of the following conditions is she most likely to have?
A Vitamin D deficiency
B Acute osteomyelitis
C Osteogenesis imperfecta
D Osteoporosis
E Polyostotic fibrous dysplasia
F Metastatic breast carcinoma
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(D) CORRECT. She most likely has osteoporosis of bone with accelerated bone loss leading to the propensity for fractures. Physical inactivity further accelerates bone loss and decreases muscle mass and agility that contribute to falls.
(A) Incorrect. A poor diet could be lacking in vitamin D, though endogenous vitamin D production occurs with sunlight exposure. The findings are those of osteomalacia and are similar clinically to osteoporosis.
(B) Incorrect. An osteomyelitis is not typical at this age and does not usually present as fractures in multiple locations.
(C) Incorrect. This inherited disorder of collagen synthesis is initially diagnosed in fetuses and young children.
(E) Incorrect. This is a rare disorder with that can be seen with McCune-Albright syndrome.
(F) Incorrect. So-called 'pathologic fracture' from weakening of bone by metastases can occur, but such patients are often very ill, with a history of weight loss, and prior bone pain.
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Question 143
A 51-year-old man has noted right hip pain for the past 3 months. On physical examination he has diminished range of motion of the right hip. A radiograph reveals a 10 x 13 cm mass involving the right ischium of the pelvis. The mass has irregular borders and there are extensive areas of bony destruction along with some scattered calcifications. The lesion is resected, and grossly the mass has a bluish-white cut surface. Which of the following attributes is most likely to describe this mass?
A The most frequent primary tumor of bone
B Usually seen in distal skeletal bones
C More common in females
D Sometimes seen to arise in benign cartilagenous tumors
E Associated with Paget disease of bone
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(D) CORRECT. Though probably a sporadic occurrence in the case desccribed here, chondrosarcomas can occur in association with osteochondromatosis.
(A) Incorrect. Osteosarcoma is the most frequent primary malignancy of bone, not chondrosarcoma.
(B) Incorrect. Distal cartilagenous tumors are more likely to be benign, whereas those in a central location are virtually always malignant.
(C) Incorrect. Primary malignancies of bone, including chondrosarcoma, are more common in males.
(E) Incorrect. Some osteosarcomas are associated with Paget disease of bone, but not typically chondrosarcomas.
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Question 144
A 62-year-old man has had back pain for 4 months. No abnormal findings are noted on physical examination. A CBC shows a WBC count of 3700/microliter, hemoglobin 10.3 g/dL, hematocrit 31.1%, MCV 85 fL, and platelet count 110,000/microliter. His total serum protein is 8.5 gm/dl with an albumin of 4.1 gm/dl. A chest radiograph shows no abnormalities of heart or lung fields, but there are several lucencies noted in the vertebral bodies. A sternal bone marrow aspirate is performed and yields a dark red jelly-like material in the syringe. Which of the following cell types is most likely to be numerous on microscopic examination of this aspirate?
A Giant cells
B Fibroblasts
C Osteoblasts
D Metastatic renal carcinoma cells
E Plasma cells
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(E) CORRECT. The patient has multiple myeloma. The bone marrow needle was in a lytic lesion filled with plasma cells. His serum globulin is high as a result of his monoclonal gammopathy.
(A) Incorrect. Giant cells may be seen in a variety of benign and malignant lesions of bone, but this does not explain the hypergammaglobulinemia.
(B) Incorrect. Fibroblasts produce collagen and are more numerous with the gross appearance of firm, white scar tissue.
(C) Incorrect. Osteoblasts are most numerous in repair of bone, and callus is very firm.
(D) Incorrect. Osteolytic metastases of renal cell carcinoma could have the gross appearance described here, but would not account for hypergammaglobulinemia.
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Question 145
A 58-year-old man has the sudden onset late one evening of severe pain in his left great toe. There is no history of trauma. On examination there is edema with erythema and pain on movement of the left 1st metatarsophalangeal joint, but there is no overlying skin ulceration. A joint aspirate is performed and on microscopic examination reveals numerous neutrophils. Over the next 3 weeks, he has two more similar episodes. On physical examination between these attacks, there is minimal loss of joint mobility. Which of the following laboratory test findings is most characteristic for his underlying disease process?
A Hyperglycemia
B Positive antinuclear antibody
C Hyperuricemia
D Hypercalcemia
E High rheumatoid factor titer
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(C) CORRECT. Many patients with gout will have hyperuricemia, but not all. The big toe is the most common joint involved with gout. Acute gouty attacks are associated with intense pain from acute inflammation.
(A) Incorrect. Hyperglycemia is a feature of diabetes mellitus, which is associated with peripheral vascular disease that increases the risk for foot ulcerations and osteomyelitis.
(B) Incorrect. The arthralgias common to many autoimmune diseases with a positive ANA, such as systemic lupus erythematosus, are not usually associated with joint swelling, redness, or deformity.
(D) Incorrect. There can be bone luceny with hyperparathyroidism, but the joints are not greatly affected, nor is there swelling or redness.
(E) Incorrect. Rheumatoid arthritis leads to marked joint deformity, typically of small joints in hands and feet. The pain usually persists for weeks to months.
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Question 146
A 13-year-old boy complains of pain persisting in his left leg for 3 weeks. On physical examination his temperature is 37.9 C. A radiograph of the leg reveals a mass in the diaphyseal region of the left femur with overlying cortical erosion and soft tissue extension. A bone biopsy is performed and the lesion on microscopic examination shows numerous small round blue cells. Which of the following neoplasms is he most likely to have?
A Ewing sarcoma
B Medulloblastoma
C Neuroblastoma
D Chondroblastoma
E Osteoblastoma
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(A) CORRECT. A 'small round blue cell' tumor of bone is Ewing sarcoma, a form of primitive neuroectodermal tumor, commonly seen at this age and in the diaphyseal region of bone.
(B) Incorrect. Medulloblastoma, though composed of small blue cells, arises in the central nervous system (posterior fossa) in children.
(C) Incorrect. Though neuroblastoma is composed of small blue cells, it typically arises in the adrenal in children.
(D) Incorrect. A chondroblastoma arises in the epiphysis of bone.
(E) Incorrect. An osteoblastoma is essentially just a large osteoid osteoma, often in vertebra.
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Question 147
A 14-year-old African man has a history of multiple episodes of sudden onset of severe abdominal pain and back pain lasting for hours. Each time this happens, his peripheral blood smear demonstrates numerous sickled erythrocytes. A hemoglobin electrophoresis shows 94% Hgb S, 5% Hgb F, and 1% Hgb A2. He now has a painful right hip that is tender to palpation. A radiograph reveals irregular bony destruction of the femoral head. Which of the following infectious agents is most likely responsible for his findings?
A Yersinia pestis
B Clostridium perfringens
C Salmonella, not typhi
D Group B Streptococcus
E Candida albicans
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(C) CORRECT. Salmonella osteomyelitis is a feature seen in patients with sickle cell anemia. Other organisms that are frequent causes for osteomyelitis with sickle cell anemia include Staphylococcus aureus and gram negatives such as Klebsiella.
(A) Incorrect. This organism is associated with plague, in septicemia, pneumonic, and bubonic (lymphadenitis) forms.
(B) Incorrect. This organism is associated with gas gangrene. In soft tissues, it can be introduced in association with trauma.
(D) Incorrect. This is not a common organism with osteomyelitis, except perhaps in the neonatal period.
(E) Incorrect. This would be a very rare finding with osteomyelitis.
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Question 148
A 70-year-old man has noted increasing back and leg pain for 3 years. He has greater difficulty hearing on the left. On physical examination he has decreased range of motion at the hips. Radiographs reveal bony sclerosis of the sacroiliac, lower vertebral, and upper tibial regions with cortical thickening, but without mass effect or significant bony destruction. If that weren't enough trouble, he says his hats don't even fit him anymore. He now has orthopnea and pedal edema. Laboratory studies show a serum alkaline phosphatase of 264 U/L. Which of the following conditions is he most likely to have?
A Metastatic adenocarcinoma
B Paget disease of bone
C Renal failure with renal osteodystrophy
D Decreased bone mass
E Vitamin D deficiency
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(B) CORRECT. There is both proliferation and destruction of bone that leads to an increase in size of the affected bone and increased blood flow that predisposes to congestive heart failure to account for these findings. Narrowing of bony canals traversed by peripheral or cranial nerves can lead to nerve palsies.
(A) Incorrect. Metastatic disease to bone produces focal lesions, not more diffuse enlargement.
(C) Incorrect. Renal osteodystrophy leads to lesions of osteitis fibrosa cystica admixed with osteomalacia, which are focal in nature.
(D) Incorrect. Osteoporosis leads to decreased bone mass, not an increase in bone size or bony sclerosis.
(E) Incorrect. Osteomalacia has an appearance similar to osteoporosis in adults.
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Question 149
An 18-year-old woman has noted pain and swelling of her right distal thigh associated with activity for the past year. She has no history of any trauma. On examination after performing physical exercise, there is tenderness on palpation above the right knee. Radiographs show an expansile, eccentric, lytic lesion located in the metaphysis of the distal femur that is surrounded by a rim of reactive new bone as a host response. Which of the following diseases is she most likely to have?
A Fibrous dysplasia
B Ewing sarcoma
C Chondrosarcoma
D Osteosarcoma
E Aneurysmal bone cyst
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(E) CORRECT. The major differential diagnosis for aneurysmal bone cyst is giant cell tumor of bone.
(A) Incorrect. This is a localized, abnormal proliferation of fibrous tissue in bone arranged with haphazard trabeculae of woven bone.
(B) Incorrect. These lesions are diaphyseal.
(C) Incorrect. Chondrosarcomas are more typical of the metaphyseal region.
(D) Incorrect. Osteosarcomas occur in the metaphyseal region.
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Question 150
A 77-year-old man has experienced persistent dull back pain for 4 months, unrelated to physical activity. He has noted a 6 kg weight loss during this time. On physical examination there are no remarkable findings. A CT scan of the spine reveals scattered 0.4 to 1.2 cm bright lesions in the vertebral bodies. Laboratory findings include a WBC count of 6700/microliter with differential of 70 segs, 8 bands, 2 metamyelocytes, 15 lymphs, 5 monos, and 2 nucleated RBCs/100 WBCs, Hgb 11.2 g/dL, Hct 33.3%, MCV 88 fL, and platelet count 89,000/microliter. Serum chemistries include sodium 144 mmol/L, potassium 4.5 mmol/L, chloride 100 mmol/L, CO2 26 mmol/L, urea nitrogen 35 mg/dL, creatinine 3.8 mg/dL, and glucose 78 mg/dL. Which of the following additional laboratory test findings is he most likely to have:
A Blood culture positive for Neisseria gonorrheae
B Parathyroid hormone, intact, of 100 pg/mL
C Serum prostate specific antigen of 35 ng/mL
D Serum calcium of 5.5 mg/dL
E Positive serology for Borrelia burgdorferi
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(C) CORRECT. A prostatic adenocarcinoma should be the first guess (particularly in a male!) with osteoblastic (bone-forming) tumor metastases. Extensive metastases can act as a myelophthisic process that leads to peripheral blood leukoerythroblastosis. His cancer may be causing urinary tract obstruction with renal failure.
(A) Incorrect. The bright areas are osteoblastic metastases, not lytic areas of osteomyelitis.
(B) Incorrect. Hyperparathyroidism should be accompanied by increased bone lucency.
(D) Incorrect. Hypocalcemia is not typically related to bone disease.
(E) Incorrect. Lyme disease can be associated with an arthritis, but not bone lesions.
143. multiple myeloma not osteosaroma is the most common primary tumour of bone.
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