Background to patient and laboratory tests:
Thirty-five-year-old Mrs Morris was referred to a rheumatology clinic by her GP, with stiffness in her fingers and wrists. Prior to her first pregnancy two years earlier, she had experienced similar symptoms, but these had receded at conception. Since the birth of her child she had found it progressively more awkward to carry out tasks involving fine finger coordination. The symptoms were worse in the mornings, although her hands felt clumsy throughout the day. She also experienced a tingling sensation in her thumb and first two fingers of each hand.
On questioning she indicated that she had been a smoker, but gave up the habit once she found out she was pregnant, and had not re-started. Since her marriage she has lived in the UK, although her father is Swedish and her mother Japanese. Her parents live in Stockholm, and she has had frequent visits to Stockholm and short summer holidays in the Stockholm archipelago area.
On examination Mrs Morris was clinically anaemic, but no jaundice, oedema or lymphadenopathy, and was afebrile. She had bilateral and symmetrical tender swellings of her wrist and proximal interphalangeal and metacarpophalangeal joints, the latter being the most marked. There was no evidence of muscle wasting in hands or arms. An examination of the elbow, shoulder, hip, knee and ankle joints failed to show any tenderness or swelling, and there was a normal range of movement in each. The spine was similarly unaffected. Respiratory and cardiovascular examinations were unremarkable. An abdominal examination did not reveal any splenomegaly.
The results of initial laboratory investigations are shown below:
Initial investigation at Rheumatology Clinic
Investigation Result (normal ranges)
Haemoglobin (g/dl) 10.1 (11.5-16.0)
Platelet count (x109/l) 245 (150-400)
Total white cell count (x109/l)
– neutrophils (x109/l)
– Total lymphocytes (x109/l) 12.5 (4.0-11.0)
8.2 (2.0-7.5)
2.1. (1.6-3.5)
Serum immunoglobulins Normal
Serum albumin (g/l) 32 (35-50)
ESR (mm/hr) 41 (<20)
C reactive protein (mg/l) 25 (<5)
IgM Rheumatoid factor Positive
ANA Negative
dsDNA-binding activity 15%
Serum complement
– C3 (g/l)
– C4 (g/l)
1.02 (0.75-1.65)
0.30 (0.20-0.65)
X-ray of hands Erosion at the distal radii and metacarpophalangeal joints
Questions:
a) What condition do you think this woman is suffering from and why? Refer to the evidence presented in the case study and laboratory result (20 marks)
b) Explain what the laboratory results mean and how they can deduce a diagnosis (10 marks)
c) Discuss the role of the immune system and the possible immune mechanisms involved in this condition (20 marks)
/50
