WBR0921

Author	PageAuthor::Vendhan Ramanujam
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Primary Care Office
Sub Category	SubCategory::Infectious Disease, SubCategory::Musculoskeletal/Rheumatology
Prompt	[[Prompt::A 45 year old female presents to her primary care physician with complaints of fatigue and pain in her proximal interphalangeal joints, metacarpophalangeal joints, wrists, elbows and knees for the past 10 days. The pain in her joints is accompanied by stiffness lasting for less than 30 minutes after prolonged rest. She also has complaints of pruritus and rashes over her arms and legs for the past 2 days. She denies any history of fever. She is a daycare worker and has been in good health previously. She further denies any history of smoking, alcohol or recent travel. She is sexually active only with her husband. Her vital signs are heart rate 82 beats/min, respiratory rate 16/minute, blood pressure 120/80 mm Hg and oral temperature 37.2 C. On physical examination, erythematous and reticular rashes are noted in her arms and legs. A swelling is elicited at the area of ulnar styloid process of the right wrist. Other joints appear to be normal. An MRI of the right wrist revealed an osseous density at the ulnar styloid process, minimal degenerative changes of the radiocarpal joint, and positive ulnar variance. A series of lab tests are ordered. Which of the following will be most likely elevated, pointing towards the diagnosis?]]
Answer A	AnswerA::Antistreptolysin titer
Answer A Explanation	[[AnswerAExp::Incorrect-Antistreptolysin (ASO) titer is specific for recent streptococcal infection and acute rheumatic fever. Arthritis of acute rheumatic fever is migratory in nature and is accompanied by carditis, chorea, erythema marginatum and sub cutaneous nodules.]]
Answer B	AnswerB::Anti-ds DNA
Answer B Explanation	[[AnswerBExp::Incorrect-Anti-ds DNA is specific for systemic lupus erythematosus, which is a multisystem disorder with other features like oral ulcers, hematological abnormalities, renal disease and rash.]]
Answer C	AnswerC::Rheumatoid factor
Answer C Explanation	[[AnswerCExp::Incorrect-Rheumatoid factor is specific for rheumatoid arthritis, which is characterized by symmetrical involvement of proximal interphalangeal joints, metacarpophalangeal joints, wrists, elbows and knees with swelling, warmth, tenderness and morning stiffness lasting for more than 30 minutes.]]
Answer D	AnswerD::Anti cyclic citrullinated peptides
Answer D Explanation	[[AnswerDExp::Incorrect-Anti cyclic citrullinated peptides are specific for rheumatoid arthritis, which is characterized by symmetrical involvement of proximal interphalangeal joints, metacarpophalangeal joints, wrists, elbows and knees with swelling, warmth, tenderness and morning stiffness lasting for more than 30 minutes.]]
Answer E	AnswerE::Anti-B 19 IgM antibodies
Answer E Explanation	[[AnswerEExp::Correct-Arthritis is the most common clinical manifestation of parvo B 19 virus in adults. The arthritis is usually non erosive (but erosive arthritis have been reported) and involves the proximal interphalangeal joints, metacarpophalangeal joints, the knees, the wrists, and the ankles with a stiffness lasting for less then 30 minutes after prolonged rest. Diagnostically, anti-B 19 IgM and IgG are specific for immunocompetent patients while nucleic acid amplification testing (NAAT) for detecting B 19 DNA is specific for immunosuppressed patients.]]
Right Answer	RightAnswer::E
Explanation	[[Explanation::The patient is most likely suffering from parvo B 19 viral arthritis. Human parvovirus B19 causes erythema infectiosum and is associated with arthritis, fetal death, and transient aplastic crisis, as well as persistent infection in immunocompromised persons, in whom it manifests as chronic anemia. While incidence of arthropathy is ∼10% in children with erythema infectiosum, in adults it is the most common clinical manifestation, occurring in 60% of female patients and 30% of male patients. Adults usually contract the infection from children at daycare centers and school. Skin rash is much less frequent. Joint symptoms typically present as acute and moderately severe nonerosive symmetric polyarthritis affecting the proximal interphalangeal joints, metacarpophalangeal joints, the knees, the wrists, and the ankles. Although erosive disease is not typical of the arthropathy of parvovirus B19 infection, it can occur and has been reported. The choice of diagnostic testing for acute B19 infection will depend on the patient's immune status. In immunocompetent individuals, the preferred method is serologic testing to detect circulating B19-specific IgM and IgG antibodies. Anti-B 19 IgM antibodies usually appear within 10 days after viral exposure and lasts for 6 months. In the immunosuppressed patient, or for congenital infections, nucleic acid amplification testing (NAAT) for detecting B 19 DNA is recommended. Educational Objective: Arthritis is the most common clinical manifestation of parvo B 19 virus in adults. The arthritis is usually non erosive (but erosive arthritis have been reported) and involves the proximal interphalangeal joints, metacarpophalangeal joints, the knees, the wrists, and the ankles with a stiffness lasting for less then 30 minutes after prolonged rest. Diagnostically, anti-B 19 IgM and IgG are specific for immunocompetent patients while nucleic acid amplification testing (NAAT) for detecting B 19 DNA is specific for immunosuppressed patients. Educational Objective: References: ]]
Approved	Approved::Yes
Keyword	WBRKeyword::Parvo B19 virus
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