100 Cases in Clinical Medicine

ANSWER 15

This patient has a monoarthropathy, a rash and red eyes. Investigations show a raised
white cell count and ESR. The diagnosis in this man was postinfective inflammatory
mucositis and arthritis, often shortened to reactive arthritis, and also known as Reiter’s
syndrome.However there is now a move to disassociate the name of Reiter (1881–1969)
from this disease in view of his crimes committed, as a doctor, by experimenting on pris-
oners in the concentration camps of Nazi Germany. This disease classically presents with
a triad of symptoms (although all three may not always be present):

• seronegative arthritis affecting mainly lower limb joints


• conjunctivitis


• non-specific urethritis.

The trigger can be non-gonococcal urethritis (NGU) or certain bowel infections. This patient
is likely to have contracted NGU after sexual intercourse in Thailand. On direct questioning
he admitted to the presence of a urethral discharge. The acute arthritis is typically a
monoarthritis but can develop into a chronic relapsing destructive arthritis affecting the
knees and feet, and causing a sacroiliitis and spondylitis. Tendinitis and plantar fasciitis may
occur. The red eyes are due to conjunctivitis and anterior uveitis, and can recur with flares
of the arthritis. The rash on the patient’s palmar surfaces is the characteristic brown macu-
lar rash of this condition – keratoderma blenorrhagica. Other features of this condition that
are sometimes seen include nail dystrophy and a circinate balanitis. Systemic manifestations
such as pericarditis, pleuritis, fever and lymphadenopathy may occur in this disease. The
ESR is usually elevated.

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• Gonococcal arthritis: occasionally a polyarthritis affecting the small joints of the
  hands and wrists, with a pustular rash.


• Acute septic arthritis: the patient looks ill and septic and the skin over the joint is
  very erythematous.


• Other seronegative arthritides: ankylosing spondylitis, psoriatic arthropathy.


• Viral arthritis: usually polyarticular.


• Acute rheumatoid arthritis: usually polyarticular.


• Acute gout: most commonly affects the metatarsophalangeal joints.


• Pseudogout: caused by sodium pyrophosphate crystals; often affects large joints in
  older patients.


• Lyme disease: caused by Borrelia burgdorfiiinfection transmitted by a tick bite; may
  have the characteristic skin rash – erythema chronicum migrans.


• Haemorrhagic arthritis: usually a history of trauma or bleeding disorder.

Differential diagnoses of an acute monoarthritis

This patient should have urethral swabs taken to exclude chlamydial/gonococcal infections,
and the appropriate antibiotics given. His knee should be aspirated. A Gram stain will
exclude a pyogenic infection and birefringent microscopy can be used to detect uric acid
or pyrophosphate crystals. This patient should be given non-steroidal anti-inflammatory