A 73 year old man presents to you complaining of a new left-sided temporal headache. His scalp is painful when he combs his hair. His jaw becomes tired and sore after a few minutes of chewing and he has had low-grade fevers in the past few weeks. These symptoms have developed in the context of a 3 month history of aching in the shoulders and hip girdle. His ESR is 90.
You are concerned that he may have temporal arteritis and decide to obtain a biopsy of the left temporal artery. Should you wait for the biopsy to be performed before treating this patient with high-dose steroids? Why or why not?
If temporal arteritis is suspected, high-dose steroids (1 mg per kg) should be started promptly. This is because 25-50% of untreated cases lead to irreversible blindness, while occasional cases lead to stroke or aortic dissection. Initiation of therapy should not be delayed to wait for a biopsy to be performed.
However, the longer the patient is on steroids prior to the biopsy, the more likely you are to obtain a false-negative result. For this reason, the biopsy should be performed within two weeks of the initiation of steroids.
When clinical suspicion for temporal arteritis is high enough, patients are sometimes treated despite a negative biopsy. This is because temporal arteritis is characterized by “skip lesions” and the biopsy may miss the area of involvement. Bilateral biopsy is superior to unilateral biopsy, and the negative predictive value of bilateral temporal artery biopsy is 90%.