A four-year-old girl came to the emergency department with a palpable purpuric rash on the lower limbs and buttocks, pain and swelling in the left ankle and on the second finger of the right hand. As a background, the week prior to the onset of the clinical picture she had acute pharyngitis.

Additional tests:

Microbiology: rapid detection of group A β-hemolytic streptococcus negative, sterile urine culture, negative blood culture.

Blood count: leukocytes 8320/mm3, haemoglobin 13 g/dl, platelets 276 000/mm3, erythrocyte sedimentation rate (ESR) in the first hour of 18 mm/h.

Coagulation tests: prothrombin time 13.9 seconds (range 10-14), Quick's index 69% (range 70-150), international normalised ratio (INR) 1.25 (range 0.85-1.15), activated partial thromboplastin time 31.4 seconds (range 26-36), fibrinogen 429 ng/ml (range 200-400).

Biochemistry: glucose 82 mg/dl, urea 20 mg/dl, creatinine 0.40 mg/dl, total/direct bilirubin 0.4/0.2 mg/dl, total protein 7.5 g/dl, albumin 3.5 g/dl, total calcium 8.6 mg/dl, GOT/GPT 23/15 IU/l, GGT 15 IU/l, lactate dehydrogenase (LDH) 254 IU/l, FA 127 IU/l.

Ions: Na 130 mEq/l, K 3.5 mEq/l, Cl 103 mEq/l.

C-reactive protein 1.05 mg/dl.

Urine sediment: no significant proteinuria or haematuria.

Due to the clinical characteristics, the case suggests Schönlein-Henoch purpura with joint involvement as a first possibility. The case evolved satisfactorily with oral non-steroidal anti-inflammatory drugs and rest.