A 9 year old boy presents with fever, abdominal pain, nausea, aching joints, and a rash. He was recently treated for an upper respiratory tract infection with amoxicillin. He subsequently developed a rash on his legs which his primary physician diagnosed as an allergic reaction to the antibiotic. The antibiotic was withdrawn and he is now taking Benadryl. The rash is no better after antihistamine treatment. Mom notes, "He probably didn't need that antibiotic anyway." He now presents with increasing abdominal discomfort, worsening joint pain, and nausea. He describes one episode of non-bilious vomiting earlier this morning.
Vital signs: T: 100.1 BP: 101/62 HR: 79 RR: 14 Sat: 99% ra
Physical Exam: Gen: He is mildly somnolent, arousable to voice, and answers questions appropriately. Oral pharynx is clear and mucus membranes are moist. Heart and Lungs are normal. Joints: diffuse tenderness with subtle edema of his knees and ankles. His is able to flex and extend with moderate discomfort. Abdomen is diffusely tender with normal bowel sounds and no distention. Skin is notable for multiple erythematous papules involving only the lower extremities (mostly below the knees).
What is your differential diagnosis...(OK sorry, name two or three things this could be...)
What is causing this?
a. Trypanosoma cruzi
b. bed bugs
c. allergic reaction to amoxicillin
d. new-onset psoriasis
e. "Da...it Jim, I'm a doctor not a dermatologist!"
What organ are you most concerned about?
Would you image this patient, if so, what test would you get?
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Weekend Update:
Henoch-Shonlein Purpura (HSP) is a vasculitis involving the small vessels of the skin, GI tract, kidneys, joints, and rarely; the lungs and CNS.
It was named after this guy (Johan Shoenlein):
And this guy (Max Purpura):
(Just kidding, this is Edouard Henoch)
They are both...you guessed it...German. PROST!!!
The Differential Diagnosis Includes:
-Idiopathic Thrombocytopenic Purpura (ITP)
-Thrombotic Thrombocytopenic Purpura (TTP)
-Rocky Mountain Spotted Fever
-Kawasaki (always keep Kawasaki in mind)
Work up in the Emergency Department is pretty limited. I would get a BMP and a CBC. Most likely these will be normal but you could see Renal involvement. The kidneys are, in my opinion, the organ that you should be most worried about. Get a UA to look for protein (nephritic/nephrotic syndrome). You could order formal Ultrasound to evaluate for appendicitis and intussusception. You would want to get a CXR if the patient reports hemoptysis. Consider a Head CT if any Neurologic complaints are present. If the patient has significant abdominal pain, and the Ultrasound is non-diagnostic, you may need to perform a CT scan of the abdomen. Finally, sometimes patients can present with scrotal swelling and you would want to get an ultrasound of the scrotum if this is present.
Treatment in the ED is basically supportive. IV fluids, replace any abnormal electrolytes. Treat pain. The use of immunosuppressive and cytotoxic drugs are becoming more common. Dapsone has been used for purport and arthralgias (but these are beyond the scope of emergency department care.)
HSP generally resolves without complications. GI and Renal complications can occur including: intussusception, bowel infarction, bowel perforation, pancreatitis, and massive GI bleeding. 20% of patients have kidney involvement and 5% develop End Stage Renal Disease (ESRD).
Thanks for playing.
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