BOF: 4
A 48-year female presents with a rash, joint pains and
weakness of her right lower limb.
On examination she has palpable purpura, no definite
arthritis but examination of the lower limb reveals common peroneal nerve
palsy.
Investigations reveal:
Haematology normocytic normochromic anaemia
White cell count normal
ESR 120 mm in 1st hour
Rheumatoid factor strongly positive
ANA negative
ANCA negative
C3 90 mg /dL (65-190)
C 45 mg/dL (15-50)
Echocardiogram normal
In this patient the likely diagnosis is:
a)
Rheumatoid arthritis
b)
Systemic lupus erythematosus
c)
Churg-Strauss syndrome
d)
Subacute infective endocarditis
e)
Mixed cryoglobulinaemia
Answer: e)
The combination of purpura, arthralgia and weakness is
known as Meltzer triad and is a feature of mixed cryoglobulinaemia.
Cryoglobulinaemia may be:
Type I
Result of monoclonal immunoglobulin excess
Type II and III
Mixed cryoglobulins which contain rheumatoid factors that
are usually IgM but may be IgG or IgA
Tissue damage is caused by immune complex deposition and
complement activation
Hypocomplementaemia usually results, especially low C4
levels
