A 55 year old man is evaluated for a 6 week history of severe fatigue, prolonged morning stiffness of the hands and feet, and arthralgia. She has a history of hypothyroidism controlled with L-thyroxine. She uses ibuprofen, which has not helped to relieve her pain. Her mother had osteoarthritis of the knees.
On physical exam, her temp is 37.1 degrees C (98.7 F), BP is 137/79, HR is 85/min, and RR is 14/min. Her BMI is 31. Heart and lung exam is normal. No rash is apparent. MSK exam reveals tenderness and swelling of the 2nd and 3rd MCP joints bilaterally. Her elbows are stiff but have full ROM and do not have signs of synovitis. There is squeeze tenderness of the bilateral metatarsophalangeal joints.
Labs
CBC wnL, Rheumatoid factor negative, TSH 1.9 mU/L, Anti-cyclic citrullinated peptide antibodies positive, IgG antibodies against parvovirus B19 positive, and IgM antibodies against parvovirus B19 negative.
Which of the following is the most likely diagnosis?
A) HypothyroidismB) Parvovirus B19 Infection
C) Polymyalgia rheumatica
D) Rheumatoid arthritis
E) Systemic lupus erythematosus
Answer: D
This patient has early rheumatoid arthritis. The peak age of onset is in the mid 50s. RA usually manifests as symmetric polyarthritis involving the small joints of the feet and hands. They may also have fever and fatigue. Rheumatoid factor assays detect IgM reactive against IgG, and is present in 50% of patients with early RA. However it is not specific and can be seen in patients with SLE, sarcoidosis, Sjogren's, and other auto-immune diseases or chronic infections. Anti-cyclic citrullinated peptide (CCP) antibodies are more specific for RA and can be present when rheumatoid factor is not. Anti-CCP also predict more severe disease, poorer functional outcomes, and radiologic progression.
Hypothyroidism can cause fatigue and rarely polyarthralgia. However, this patient has normal TSH levels.
Parvovirus B19 may manifest as fever, fatigue, RF positive, and joint manifestations like RA. However, this condition is self-limited and usually resolves after several months. The "slapped cheek" rash of erythema infectiosum in children is rarely seen. The absence of IgM antibodies against parvovirus B19 argue against active infection. The presence of IgG antibodies against parvovirus B19 may be related to a previous infection.
Polymalgia rheumatica usually presents as aching, fatigue, and morning stiffness in the shoulder and hip girdles. It is sometimes associated with giant cell arteritis. Symmetric, small joint involvement and frank joint swelling are only seen in a minority of patients with PMR. These patients usually have markedly elevated ESR and anemia. This patient lacks shoulder and hip girdle symptoms.
SLE develops more frequently in reproductive age women. It may be associated with polyarthritis and constitutional symptoms but rarely without systemic manifestations, such as rash, cytopenias, and pleuritis.
Key Points
Anti-CCP antibodies are more specific for RA than rheumatoid factor and may be present in early disease when RF levels are normal.
Reference: Maijithia V. Rheumatoid arthritis: diagnosis and management. Am J Med 2007; 120: 936.
Because anti cyclic citrullinated peptide is very specific (>90%) for RA that this pt has RA despite a negative RF.
answer is D.
I think B. PARVOVIRUS B19 infection. Arthropathy typically develops after serum antibodies for Parvovirus become positive.
PS: I have never heard of Anti-cyclic citrullinated peptid antibodies, is there another name for it?
D.