A 32-year-old woman complains of having intermittent arthralgias of multiple joints and occasional swelling in both knees. The symptoms started about 6 months ago and usually last for weeks at a time and then improve spontaneously. She reports no morning stiffness or any constitutional symptoms. About 1 year ago, she recalls having a round, red, pruritic skin lesion along her belt line, which resolved on its own. Serologic tests confirm a clinical diagnosis of Lyme disease. Which of the following mechanisms is the most likely cause of this syndrome?
This story is typical of Lyme disease. The spirochete involved (B. burgdorferi) is transmitted by ixodic ticks and is most common in the Northeastern and Midwestern parts of the United States. The host animal varies depending on the exact type of tick.
A 74-year-old man presents with a history of increasing frequency of headaches, fatigue, and weight loss for 3 months. He has had migraine headaches in the past, but these are different from them. He is also experiencing back, shoulder, and hip discomfort, which is worse in the morning. His head and neck examination is normal. Range of motion in the shoulders and hips is reduced because of discomfort but there is no active inflammation. Which of the following signs or symptoms is most helpful in the diagnosis?
Although malaise, fatigue, and sweating are common in temporal arteritis, they are too nonspecific to help in making the diagnosis. Claudication of the jaw and tongue, while not very sensitive for temporal arteritis, are more specific than the constitutional symptoms. Odynophagia is not a characteristic of this dis
A 60-year-old man has pain in his left hand and right knee, which is interfering with his work. The pain came on gradually, first in his hand 6 months ago and now in his knee. It is usually fine when he wakes up, but gets worse as the day progresses. There is no history of any trauma, and he is otherwise well. Taking over-the-counter NSAIDs usually relieves the pain. On examination, there is bony soft tissue swelling of his second and third DIP joints in the left hand and crepitus over the right knee with flexion. There is no erythema or joint effusion. Which of the following characteristics is a risk factor for this condition?
There are numerous diseases and risk factors associated with the development of osteoarthritis. People of Chinese and African heritage have a lower risk than Caucasians, while Native Americans have a higher risk. Women are more affected than men, and obesity is a significant risk factor. Hyperthyroidism is not one of the many metabolic/endocrine disorders associated with osteoarthritis.
Which of the following is the most common location for osteoarthritis?
Heberden’s nodes, bony enlargement of the DIP joints of the hand, are the most common type of osteoarthritis. Although they can present acutely with pain and inflammation, they are frequently slow in developing and relatively asymptomatic.
A 67-year-old woman develops symptoms of cough and sputum production after an upper respiratory tract infection. A CXR does not show any signs of pneumonia but the report mentions a “pseudofracture” sign (Looser zones) seen in the left scapula compatible with osteomalacia. She has no pain in the scapula. Which of the following best differentiates rickets and osteomalacia?
Both rickets and osteomalacia are disorders in which mineralization of the organic matrix of the skeleton is defective. Rickets is the name when this disorder occurs in a growing skeleton, whereas osteomalacia occurs after the epiphyseal plates are closed.
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A 72-year-old man is recently found to have hypocalcemia and osteomalacia is suspected based on the decrease in the cortical bone thickness and osteopenia is seen on x-rays. Which of the following is the most likely mechanism of the resistance to the effects of vitamin D?
Deficient or defective 1,25(OH)2 vitamin D receptors will result in vitamin D resistance. Parathyroid hormone levels increase secondary to decreased vitamin D effect. The 1(OH) vitamin D is an intermediate metabolite.
A 66-year-old woman complains of pain in her left hip when walking. Three days ago, she tripped and fell in her apartment. On examination, there is decreased range of motion in the hip, no leg length discrepancy. X-rays of the hip reveal osteopenia. Which of the following is the primary defect in vitamin D metabolism that causes osteopenia associated with aging?
Aging decreases the responsiveness of the renal 25(OH) D-1-hydroxylase to parathyroid hormone (PTH), thus decreasing circulatory levels of the active metabolite 1,25(OH)2 vitamin D. This results in decreased calcium absorption from the gut. There is not a close relationship of 1(OH) vitamin D levels and osteopenia.
Which of the following clinical findings is characteristic of both osteomalacia and rickets?
Muscle weakness is common in both rickets and osteomalacia, and proximal leg muscles are particularly involved. The combination of leg deformity and muscle weakness in rickets can result in an inability to walk. The presentation of osteomalacia is more insidious in the elderly, but proximal myopathy may be severe enough to cause a waddling gait and mimic a primary muscle disorder. The other clinical findings listed are found only in rickets.
An 84-year-old man, previously well except for chronic osteoarthritis, develops a hot, red, painful knee. Physical examination reveals an exquisitely tender, swollen knee. Which of the following is the most likely finding on synovial fluid analysis?
The term pseudogoutrefers to crystal deposition disease not due to uric acid (gout). By far the most common cause of pseudogout is calcium pyrophosphate deposition (CPPD). The major predisposing factors are advanced age and preexisting joint disease. The knee is the most common joint involved, and presentation can mimic acute gout. However, in the majority of cases, the deposition of calcium pyrophosphate seems to be asymptomatic.
A 74-year-old man has recurrent attacks of pain, swelling, and redness in his left knee. He has background osteoarthritis of both knees, which require him to take acetaminophen on a regular basis. Joint fluid was removed during one acute episode of knee pain, and synovial fluid analysis revealed calcium pyrophosphate deposition disease crystals (CPPD). Which of the following methods is the most effective prophylaxis for this condition?
Unfortunately, there is no medical means to remove the deposits of CPPD. Colchicine does seem to decrease the rate of recurrence. NSAIDs, steroids (systemic or intra-articular), and colchicine are all helpful in acute attacks.
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A 79-year-old woman on chronic hemodialysis presents with severe pain in her left knee. On examination, the knee is warm, swollen, and painful to move. Diagnostic joint aspiration is performed. Which of the following is the most likely finding in her joint fluid?
Although gout and CPPD disease are found in chronic renal failure, hydroxyapatite deposition is characteristic of end-stage renal failure. The crystals are very small, nonbirefringent, and only seen on election microscopy. Treatment is symptomatic, and similar to the treatment of gout or CPPD disease.
An 81-year-old woman develops progressive pain and immobility of her right shoulder. A series of x-rays over 8 months reveals destruction of the shoulder joint and an aspiration reveals blood in the effusion. Her only other articular manifestations are mild episodes of pain in her knees. Which of the following is the most likely diagnosis?
“Milwaukee shoulder” represents an unusual manifestation of calcium hydroxyapatite deposition disease. Once destruction changes start occurring, medical management is relatively unsuccessful. The exact reason why destructive arthritis occurs is not understood. The knee is the other joint affected in this manner.
A 59-year-old woman with RA, under reasonable control with methotrexate, develops a hot, swollen, red knee. Joint aspiration removes 10 cc of an opaque yellow-colored fluid with a white count of 100,000/µL, predominantly neutrophils. The joint fluid protein is high and glucose is much lower than blood. Which of the following is the most likely diagnosis?
The high white cell count suggests infection. In RA and crystal-induced arthritis, the white cell count is usually less than 50,000/µL. Staphylococcus aureusinfection is the most common type in RA.
A 48-year-old man presents with 3 weeks of fever, fatigue, and shortness of breath. He has a history of “nasal allergies” and asthma, which have been poorly controlled in the past month. Two days prior to presentation, he developed weakness in his left foot and it now “drags” when he walks. On examination, his blood pressure is 165/90 mm Hg, pulse 100/min, respirations 20/min, and lungs have bilateral expiratory wheezes. There is left foot drop, and the rest of the neurologic examination is normal. Laboratory evaluation reveals ESR of 90 mm/h, WBC of 14,000/mL with 10% eosinophils, and 1+ proteinuria. A CXR shows bilateral pulmonary infiltrates.
Churg-Strauss is a granulomatous vasculitis. Pulmonary involvement often dominates the clinical presentation with severe asthma attacks and pulmonary infiltrates. Peripheral eosinophilia is present in virtually all cases.
A 39-year-old man has had several weeks of fever, weight loss, and lack of energy. Three days prior to the assessment, he developed a left foot drop. Physical examination confirms left peroneal nerve damage and a bilateral sensory peripheral neuropathy in both legs. Laboratory evaluation reveals ESR of 105 mm/h, neutrophilia of 14,000, and a negative serologic test for ANCA. Eosinophil count is normal. Angiography reveals small aneurysms of the celiac and renal arteries.
PAN is a multisystem, necrotizing vasculitis of small- and medium-sized muscular arteries. Aneurysmal dilations of the arteries are characteristic. Nonspecific signs and symptoms are the usual method of presentation. Renal involvement is clinically present in 60% of cases and is the most common cause of death in untreated cases.
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A 40-year old man complains of cough, shortness of breath, and nasal ulcers. He was previously well until 1 month ago. He noticed some blood in his sputum on the day of presentation. On examination, his blood pressure is 170/90 mm Hg, pulse 90/min, respirations 22/min, and there are bilateral inspiratory crackles. The oral cavity is normal, but there is a 1-cm nasal septal ulcer. Investigations reveal a positive c-ANCA, 3+ proteinuria with red cell casts, and pulmonary infiltrates on the CXR. His ESR is 110 mm/h and WBC 12,000/mL with normal eosinophils.
A high percentage of patients with Wegener’s develop ANCAs. In particular, cytoplasmic or c-ANCAs are both sensitive and specific for Wegener’s. However, tissue diagnosis is still required.
A 24-year-old woman presents with abdominal pain, joint discomfort, and lower limb rash. She was well until 1 week before presentation. On examination, she has a palpable purpuric rash on her legs, nonspecific abdominal discomfort, and no active joints. She has 3+ proteinuria, normal WBC, no eosinophils, and elevated creatinine of 1.6 mg/dL. Biopsy of the rash confirms vasculitis with immunoglobulin A (IgA) and C3 (complement 3) deposition on immunofluorescence.
Henoch-Schönlein purpura, characterized by palpable purpura, arthralgias, GI symptoms, and glomerulonephritis, can be seen in any age-group but is most common in children. It can resolve and recur several times over a period of weeks or months and can resolve spontaneously.
A 34-year-old man has recurrent painful oral and genital ulcers. Recently, he has noticed multiple painful joints and a decrease in his vision. Last year he had deep vein thrombosis that required treatment. On examination, he has multiple small shallow oral ulcers and similar lesions on his scrotum. The left eye is red and tearing, while his left wrist and right knee are warm and inflamed. Laboratory investigations including complete blood count (CBC), biochemistry, and ANCA are all normal. His ESR and C-reactive protein are elevated.
Behçet’s syndrome is a leukocytoclastic venulitis characterized by episodes of oral ulcers, genital ulcers, iritis, and cutaneous lesions. Eye involvement can rapidly progress to blindness.
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