Clinical case 1

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[edit] Case presentation

The rash.

A 30-year old man comes to the accidents and emergencies department with a presenting complaint of rash on both lower legs. He first noticed the rash two days earlier, but it progressively got worse. The rash itself is not painful but he has felt waxing and waning pains in his knees and ankles. He has also felt some nausea and colicky abdominal pain without vomiting or a change in bowel motions or stool appearance. He has not felt any fever or chills and denies urinary or respiratory problems. There have been no recent illnesses, no weight changes or night sweats.

The man has type 1 diabetes for which he has been on insulin injections since childhood. He has not take any other prescription or over-the-counter drugs and has no known allergies. He's a non-smoker who admits to occasional use of alcohol. He doesn't know details about medical conditions in his family. The patient works as a teller in a bank, is married and lives in the city with his wife and baby daughter.

His vital signs are as follows: temperature 37.1 °C (98.8 °F), pulse 74 bpm, blood pressure 160/90 mmHg, respiratory rate 12/min.

On physical examination, there is a non-blanching rash predominantly on the legs but extending to the lower back. The lesions are dark red and slightly raised. The patient admits to pain on deep palpation in all four quadrants of the abdomen. Bowel sounds are normal and no masses or organomegaly can be felt. There is no redness or swelling of the joints of the lower extremities. The lungs are clear to auscultation and heart sounds are normal. Examination of the head, eyes, ears, nose and throat are normal. No enlarged lymph nodes are palpated. There are no signs of meningeal irritation. A digital rectal examination shows a streak of blood on the finger. Further physical examination is unremarkable.

An electrocardiogram is found to be completely normal.

Laboratory tests are remarkable for leukocytosis (18,000 white blood cells /µl) and raised serum C-reactive protein (180 mg/L) and erythrocyte sedimentation rate (75 mm/h). There is also a raised creatinine (1.23 mg/dl,or 107 μmol/l) and glucose (138 g/l, or 7.7 mmol/L). The platelet count is 450,000/µl. Clotting tests are within normal limits. Liver enzymes, thyroid function tests, lactate dehydrogenase and creatine phosphokinase are within normal limits.

[edit] Your diagnosis

  • Question: What is the differential diagnosis?
Answer

Vasculitis

Purpura can be seen in systemic infections (e.g. disseminated intravascular coagulation in meningococcal sepsis, systemic gonorrhoea, emboli such as in endocarditis, or rickettsial diseases), idiopathic thrombocytopenic purpura, haemolytic uremic syndrome, leukaemia or other forms of neoplasia or coagulopathies. However, the clinical picture of palpable purpura combined with the blood count and normal clotting tests does not support these diagnoses. A number of small vessel vasculitides should be considered in this case, especially Henoch-Schönlein purpura (HSP), given the combination of palpable purpura, arthralgia, abdominal pain and hypertension (which might indicate renal involvement) in this patient. Platelets can be slightly raised in HSP.


1. What tests might be useful in this case?

Chest X-ray
Urinalysis
Creatinine clearance
Serum protein electrophoresis
Rheumatoid factor (RF)
Antinuclear antibodies (ANA) and antineutrophil cytoplasmic antibodies (ANCA)
Serum complement levels
Cryoglobulins
Anti-streptolysin O titers
Hepatitis serology
Anti-glomerular basement membrane (GBM) antibodies
Microscopic examination and immunofluorescence of a skin lesion
Abdominal ultrasound
Coronary catheterisation
Electromyography (EMG)
→
Microphotograph of a histological section of human skin prepared for directimmunofluorescence using an anti-IgA antibody. The skin is a biopsy of a patient with Henoch-Schonlein purpura. IgA deposits are found in the walls of small superficial capillaries (yellow arrows). The pale wavy green area on top is the epidermis, the bottom fibrous area is the dermis.
Pulmonary complications are rare but have been reported in Henoch-Schönlein, and a chest X-ray might show abnormalities in other vasculitides or unsuspected infections. Given the patient's hypertension, a urinalysis would be useful to determine proteinuria and haematuria, since renal involvement is common in several small vessel vasculitides. Since creatinine by itself is a poor marker of kidney function, further attempts should be made to evaluate kidney function (for example with creatinine clearance). Electrophoresis may show a peak in the gammaglobuline fraction -raised IgA levels would raise the suspicion for Henoch-Schönlein purpura even more. IgA levels are raised in 50-70% of HSP cases. Vasculitis can also occur in the context of other disorder such as rheumatoid arthritis, systemic lupus erythematosus or other connective tissue disorders, so RF and ANA are useful. Classically, c-ANCA is associated with Wegener’s granulomatosis and p-ANCA is associated with microscopic polyangiitis. Low complement levels may be present in lupus and cryoglobulinaemia. Several reports indicate that anti-streptolysin O titers are often raised in patients with Henoch-Schönlein purpura. This may also be helpful if the distinction from acute rheumatic fever is uncertain. Chronic hepatitis (especiallly hepatitis C) can cause vasculitis, although liver tests would generally be abnormal, and the patient has no obvious risk factors. Given the clinical picture, Goodpasture's syndrome is unlikely, so anti-GBM antibodies are not useful. Skin microscopy and immunofluorescence would probably be the most useful test for the definite diagnosis in suspected Henoch-Schönlein purpura. Abdominal ultrasound can be useful to assess bowel wall thickness and to look for intussusception. Coronary catheterisation is useful only if a medium-sized vasculitis, such as polyarteritis nodosa or Kawasaki disease, is suspected. An EMG is useful if there is a vasculitis presenting with mononeuritis multiplex.

2. What is the single most likely complication in this patient?

Joint deformity
Bowel perforation
Intussusception
Renal failure
Hemothorax
Stroke
→ Intussusception is extremely rare in adults with Henoch-Schönlein purpura, whereas renal failure is very common in adults.

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[edit] Case discussion

Case discussion

Henoch-Schönlein purpura in adults

Henoch-Schönlein purpura (HSP) is a systemic leukocytoclastic vasculitis characterized by the deposition of IgA immune complexes. It occurs most often in young children but it should be suspected in adults with palpable purpura (especially on the lower extremities and buttocks) and other typical features such as joint, abdominal and renal involvement. HSP seems to run a more severe course in adults. Complications are also different as compared to children, in whom intussusception is more common and renal failure is rarer. In a series of 37 adults with HSP, ten (27%) developed end-stage renal disease. Severe renal involvement at presentation (e.g. strong proteinuria or hypertension) has been suggested as a predictor of subsequent renal impairment. In this case, abdominal symptoms and renal involvement should prompt consideration for the use of intravenous corticosteroids. Given this patient's diabetes, other immunosuppressive drugs might be considered.

Vasculitides typically present with either palpable purpura, simultaneous lung and kidney disease or mononeuritis multiplex. Since HSP is rare in adults, other forms of vasculitis need to be excluded. Hypersensitivity vasculitis presents with fever, lymphadenopathies, arthralgia but without glomerulonephritis, and is usually secondary to infections or medications. Small vessel vasculitis can also be secondary to connective tissue diseases or infections (most commonly hepatitis B and C but also HIV, cytomegalovirus, Epstein-Barr virus, and parvovirus B19). Other small vessel vasculitides can be differentiated by their clinical presentation and laboratory tests (as described above).

References

Pillebout E, Thervet E, Hill G, Alberti C, Vanhille P, Nochy D (May 2002). "Henoch-Schönlein Purpura in adults: outcome and prognostic factors". J. Am. Soc. Nephrol. 13 (5): 1271–8. PMID 11961015. 

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