Use of Special Stains and Immunohistochemistry To Diagnose Giant Cell Arteritis.
Elizabeth Verner-Cole, Mukul Divatia, Dan Gombos, Patricia Chevez-Barrios. The Methodist Hospital, Houston, TX; MD Anderson Cancer Center, Houston, TX
Background: Giant cell arteritis (GCA) is usually diagnosed on temporal artery biopsy using slides stained with hematoxylin and eosin (H&E), yet pathologists at times implement special stains and immunohistochemistry to confirm the diagnosis when it is in question, and little is reported on the frequency with which that is done. We present here trends from our institution of the use of these additional tests in diagnosing giant cell arteritis.
Design: Retrospective chart review of temporal artery biopsies from January 2008 to September 2010.
Results: Over a 2 ½ year period, 95 temporal artery biopsy specimens were received, of which 65 (68.4%) were negative for either active or treated GCA, 21 (22.1%) showed evidence of healed/treated GCA, 7 (7.4%) were positive for active GCA, and 2 cases (2.1%) had insufficient tissue for diagnosis. The mean age of patients with active GCA was 81 years old. Half of the positive cases of active GCA (4/7) required no additional special stains or immunohistochemistry to confirm the diagnosis following hematoxylin and eosin (H&E) slide preparation. Movat's pentachrome stain was the most commonly used special stain (55 cases, 57.9%). Immunohistochemistry with CD68 to stain macrophages was used in 15 cases (15.8%), always in conjunction with Movat's pentachrome. CD3 to highlight T lymphocytes was used in 9 cases (9.5%) in which healed/treated arteritis was suspected based on histologic features such as fibrosis of the tunica media and breaks in the internal elastic lamina without significant giant cell reaction.
Conclusions: Giant cell arteritis can be diagnosed on temporal artery biopsy using H&E stain alone, yet almost half of the positive cases from our institution required additional tests to confirm the diagnosis. When not seen easily, Movat's pentachrome stain provides excellent visualization of the internal elastic lamina, including segmental absence of elastic lamina associated with muscular layer fibrosis as seen in GCA. Correlating those results with histiocytes (CD68) and T cells (CD3) present at the intima-media junction allows for further confidence in the diagnosis.
Wednesday, March 2, 2011 1:00 PM
Poster Session VI # 289, Wednesday Afternoon