A 27-year-old man presents with worsening low back pain over the past 5 months. He reports that the pain is most severe in the morning and describes a “back stiffness” when getting out of bed. He reports moderate improvement with walking. The patient denies any systemic symptoms and reports an insignificant past medical history. On physical examination, the patient is afebrile with normal vital signs. On musculoskeletal examination, there is marked tenderness over the sacroiliac joints with limited range of motion on forward flexion of the lower back.
Of the following tests, which is the best test for the likely diagnosis in this patient?
Plain film x-ray of the sacroiliac joints. The patient in this question is presenting with signs and symptoms consistent with ankylosing spondylitis (AS). AS is one of the seronegative spondyloarthropathies, which are joint diseases affecting the vertebral column that are characterized by a negative rheumatoid factor (RF) and ANA. AS is more common in men, typically occurs in the second and third decades of life, and is characterized by progressive low back pain and stiffness lasting at least 3 months in duration. Morning stiffness and improvement with exercise are also common with this condition. In order to confirm the diagnosis, anteroposterior (AP) x-ray of the sacroiliac (SI) joints is performed. Fusion of the SI joints (the presence of a “bamboo spine”) is diagnostic and a specific indicator for the diagnosis of AS.
(A) MRI of the spine would only be necessary if the x-ray of the lumbar spine returns negative and AS is clinically suggested. (B) Although patients with AS have an increased incidence of positivity for HLA-B27 (90% of patients), it is not a specific test because only a minority of patients demonstrating positivity for HLA-B27 actually has AS. (D) AS is a seronegative spondyloarthropathy, so by definition it is negative for RF levels.
A 47-year-old woman who has not seen a physician in over 20 years presents with painful joints, fatigue, weakness, and what she describes as “hideously misshapen hands.” Family history is significant for type 1 diabetes. Physical examination reveals deformed hands and a 2-cm soft mass that that is mobile and tender to palpation in the left popliteal fossa.
Which of the following is the underlying pathophysiology of this popliteal fossa mass?
Fluid production from inflamed synovium. This patient is presenting with signs and systemic symptoms consistent with rheumatoid arthritis (RA). The tender mass in the popliteal fossa is likely a Baker cyst, a benign swelling of the synovial bursa found behind the knee joint. Baker cysts are caused by excessive fluid production from the inflamed synovium that commonly occurs in rheumatoid arthritis, a systemic inflammatory disorder that primarily attacks synovial joints. (A) Urate crystal deposition is a finding in gout, but this would cause the knee to be painful, erythematous, and swollen. Furthermore, it would be highly unusual for the swelling seen in a gouty knee flare to be limited to the popliteal fossa. (B) Redundant bone growth would not be tender and soft on physical examination. Such bone growth can be seen as osteophytes in osteoarthritis. (C) Obstruction of lymphatic drainage causes lymphedema, which is highly unlikely to occur in the popliteal fossa.
A 47-year-old obese man presents with pain in his bilateral knees that has worsened over the last year. The pain is alleviated by rest and worsened by walking. The patient has never taken any medications for the pain, but warm compresses temporarily cause relief. The patient has a history of type 2 diabetes and hyperlipidemia. Physical examination shows a BMI of 33 kg/m2 . A “grating” sound is appreciated on palpation over the knee joints bilaterally.
Which of the following is the best initial treatment for this patient?
Acetaminophen. This patient is obese, greater than 40 years of age, and is presenting with bilateral knee pain. The fact that the pain is worsened with activity and relieved by rest suggests that it most likely secondary to osteoarthritis (OA). If he reported morning stiffness lasting greater than 30 minutes and had systemic symptoms, rheumatoid arthritis would have been the likely diagnosis. OA is a noninflammatory arthritis that results in eroding cartilage in the intra-articular joints. This causes joint crepitus (a “grating” or popping sound) that occurs when the surfaces of the joint grind against each other. Although the diagnosis is usually made clinically, the typical changes seen on x-ray include joint space narrowing, subchondral sclerosis (increased bone formation around the joint), subchondral cyst formation, and osteophytes (Figure below shows the articular changes seen in osteoarthritis and rheumatoid arthritis). Acetaminophen is the first-line treatment for mild to moderate OA. It is just as efficacious as NSAIDs in alleviating the pain in OA with considerably fewer side effects. Nonetheless, while most guidelines do indeed recommend acetaminophen as first-line treatment for pain, acetaminophen toxicity remains a real public health concern as it is the leading cause of acute liver failure in the United States. The therapeutic window of acetaminophen is not wide; in fact, toxicity occurs just above the recommended 4 g/d for adults.
(A) Intra-articular corticosteroid injections lead to short-term pain relief that lasts up to a few months. This should not be the initial treatment in OA. (C) Naproxen is an NSAID and although NSAIDs have been shown to be efficacious in the treatment of OA, their side effect profile consists of gastrointestinal and renal consequences that make them second-line treatments. (D) Allopurinol is used in the prophylactic treatment of gout. It acts via inhibition of xanthine oxidase, which decreases production of uric acid. It is not used in the treatment of OA.
A 53-year-old woman presents with a 2-week history of fatigue and weakness in her hips. She has also started developing weakness in her shoulders while trying to brush her hair in the mornings. The patient denies any difficulty chewing, blurry vision, or facial weakness. The patient is otherwise healthy and does not report any family history other than pancreatic cancer in her maternal uncle. Neurologic examination reveals 3/5 strength in the proximal muscles of her upper and lower extremities. The patient’s erythrocyte sedimentation rate (ESR) is elevated at 92 mm/h and the creatine kinase (CK) is moderately elevated. Other laboratory values (including TSH and free T4) are within normal limits.
Which of the following is the most likely diagnosis in this patient?
Polymyositis. The patient in this question is presenting with signs, symptoms, and laboratory values consistent with a diagnosis of polymyositis, an inflammatory myopathy characterized by proximal muscle weakness. Dysphagia and esophageal dysmotility occur in as many as onethird of patients. It typically occurs between 40 and 50 years of age and women are more commonly affected. The elevation in ESR and CK levels support the diagnosis of an inflammatory myopathy. Polymyositis can be confirmed by electromyography (EMG) and positive muscle biopsy. It is treated with corticosteroids. (A) ALS presents with weakness as well, but it is associated with upper and lower motor neuron deficits. (C) Drug-induced myopathy (commonly caused by alcohol, antipsychotic medications, and statins) would present clinically with similar symptoms, but would not have an elevated ESR and CK. (D) Fibromyalgia typically presents with pain, not objective weakness, and would have normal ESR and CK levels.
A 67-year-old woman presents with severe headaches, joint pain, painful chewing, and fever. On physical examination, prominent vasculature is noted in the temporal region of the scalp. Decreased pulses are noted throughout the body. Laboratory testing reveals an ESR of 94 mm/h.
Which of the following is associated with this condition?
Aortic aneurysm. The patient in this question is presenting with signs, symptoms, and laboratory values consistent with a diagnosis of giant-cell arteritis (GCA), also known as temporal arteritis. Symptoms can include headache, visual problems, jaw claudication, fever, and temporal scalp tenderness. GCA is a vasculitis most commonly involving large and medium arteries of the head, predominantly the branches of the external carotid artery. A decreased temporal artery pulse can be noted as well. ESR and C-reactive protein are commonly elevated. High-dose corticosteroids should be started as soon as the diagnosis is suspected (even before confirmation by biopsy) to prevent irreversible blindness secondary to ophthalmic artery occlusion. GCA can involve branches of the aorta leading to aortic aneurysm, thus patients should have serial chest x-rays performed.
(B) Inflammatory bowel disease includes ulcerative colitis and Crohn disease and is not associated with GCA. (C) Hepatitis B is associated with polyarteritis nodosa (30% of the time), a vasculitis of medium- and small-sized arteries. (D) A smoking history is seen in thromboangiitis obliterans (Buerger disease), which presents with progressive inflammation and thrombosis of small and medium arteries of the hands and feet. Ulceration and gangrene are common complications.
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