Histologic parameters helpful to recognize steroid-treated temporal arteritis: An analysis of thirty-five cases

Abstract

This study was performed in order to establish the important histologic and immunohistochemical parameters that are helpful in recognizing temporal arteritis in patients who have been treated with steroids prior to the biopsy, and to analyze the clinical features and correlate them with the histologic findings. A retrospective review of charts of 35 patients treated with steroids prior to obtaining temporal artery biopsy specimens, spanning an 11 year period from1995 to 2005. The study was conducted at the Ophthalmic Pathology Laboratory at the Cullen Eye Institute. The clinical features were evaluated and correlated with the histopathologic findings. Each case was evaluated with respect to age, gender, race, clinical findings, erythrocyte sedimentation rate, corticosteroid dosage (oral vs intravenous), and the duration of the treatment. The time interval between obtaining the biopsy specimen and the onset of steroid therapy was carefully recorded from each patient. In selected cases, histiocytic markers (CD68 and HAM-56) were performed to identify the presence of epithelioid histiocytes, which characterizes a granulomatous inflammation. Other immunohistochemical studies (CD3, CD20, CD4, CD8, CD45RO, CD45RA, and S-100 protein) were performed in selected cases to characterize the inflammatory cells. The authors believe that the three most reliable histopathologic parameters of corticosteroid-treated temporal arteritis are the following: 1) Complete or incomplete mantle of lymphocytes and epithelioid histiocytes located between the outer muscular layer and the adventitia, 2) large circumferential defects in the elastic lamina (best seen with the Movat pentachrome), and 3) absent or few small multinucleated giant cells. In some cases the main artery appears normal while the primary branches show evidence of a healing arteritis. The histologic findings vary according to the route of steroid administration (oral vs intravenous) and the duration of treatment prior to obtaining the biopsy specimen. Striking histologic differences can be recognized objectively between patients with active (untreated) giant cell arteritis (GCA) and patients who have been treated with corticosteroids. The earliest histopathologic changes were detected by the end of the first week following steroid therapy (usually after day 4 to the end of the first week). The histologic findings were more difficult to recognize after two to three months following steroid treatment. We believe ophthalmic and general pathologists should be able to recognize this entity on the basis of the histologic findings including the special stains and results of immunohistochemical markers (CD68 and HAM-56).—Hans E. Grossniklaus