A five-year-old boy is brought to the clinic for colicky abdominal pain that started four hours ago. He recently recovered from a case of Parvovirus B19 infection and had been doing well until today. The patient has no notable medical history aside from the Parvovirus infection and is not currently on any medications. Physical examination reveals a cropping of erythematous rashes bilaterally on the lower extremities. The joints in the knees and ankles are also swollen and tender to palpation. White blood cell count, hemoglobin, platelet count, and coagulation studies are normal. Urinalysis and serum creatinine are within normal limits. He is started on naproxen for pain control.
D) IgA vasculitis
IgA vasculitis is usually distinguished by its hallmark rash that develops into palpable purpura. Gastrointestinal pain and arthralgias are also common symptoms that accompany this disorder. IgA vasculitis is commonly acquired after a viral upper respiratory infection, but other infections such as group A streptococcus or chemical exposures can also precipitate the disorder. Renal involvement is present in 21-54% of cases, though this patient does not have evidence of renal involvement such as hematuria or elevated creatinine.
Answer choice A: Cryoglobulinemia vasculitis, is incorrect. Although cryoglobulinemia can also present with palpable purpura and arthralgias, it is distinguished by its association with chronic hepatitis C infection. In addition, blood tests would demonstrate cryoglobulin accumulation at colder temperatures.
Answer choice B: Giant cell arteritis, is incorrect. Giant cell arteritis usually only affects adults (more commonly women) over the age of 50. In addition, the patient would present with headaches and jaw claudication rather than a rash. An important distinction here is the fact that this is a large vessel vasculitis while IgA vasculitis is a small vessel vasculitis.
Answer choice C: Granulomatosis with polyangiitis, is incorrect. Although granulomatosis with polyangiitis does affect children, this disorder is distinguished by its involvement with the lungs, kidneys, and nasopharynx, none of which are mentioned in the question. In addition, blood tests would show C-ANCA, a key marker of the disease.
Answer choice E: Kawasaki disease, is incorrect. Although this disorder does affect children and presents with a rash, the hallmark for Kawasaki disease is a prolonged fever of five or more days. Remembering the mnemonic CRASH and burn also provides other distinguishing symptoms: Conjunctivitis, Rash, Adenopathy, Strawberry tongue, Hand/feet changes, Burn (fever).
Key Learning Point
IgA vasculitis is a small vessel vasculitis that primarily affects children after an infection such as a viral upper respiratory infection. It presents with palpable purpura, arthritis, abdominal pain, and sometimes renal disease. The pathophysiology of this disease is IgA immune complex deposition in the capillaries. The diagnosis of this particular disease is usually clinical rather than through laboratory tests. This demonstrates the necessity of understanding common age groups affected as well as hallmark associations when trying to distinguish between vasculitides.
