Muscle specific actin clone hhf35

Immunohistochemistry for CD99 (clone 12E7; Leica, Buffalo Grove, IL; prediluted), pancytokeratin (PCK26; Ventana, Tuscon, AZ; prediluted); p40 (Ab-1; Oncogene Research Products, Cambridge, MA; 1:2000 dilution), synaptophysin (clone 27G12; Leica Microsystems; prediluted); chromogranin (clone LK2H10; Ventana; prediluted); S100 protein (clone 4C4.9; Ventana; prediluted), muscle specific actin (clone HHF35; Ventana, prediluted); desmin (clone D33, Dako, Carpinteria, CA; 1:100 dilution), NUT-1 (clone C52B1, Cell Signaling Technologies, Inc., Danvers, MA, 1:50 dilution), and p16 (clone INK4a; MTM Laboratories, Heidelberg, Germany); was performed on five-micron sections utilizing standard protocols on a Ventana Benchmark XT autostainer. In addition, in situ hybridization for high-risk types of human papillomavirus was also performed utilizing the Ventana HR HPV III probe set that captures HPV genotypes 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58 and 66. The sinonasal tissue microarray was also stained with CD99.

Immunohistochemical studies were performed on five-micrometer thick sections prepared from formalin-fixed and paraffin embedded tissue. Most of the immunohistochemistry was done at The Johns Hopkins Hospital, where the primary antibodies were: p16 (clone INK4a; MTM Laboratories, Heidelberg, Germany); p63 (clone 4A4; Cell Marque Corp., Rocklin, CA); p40 (clone Ab-1; Oncogene Research Products, Cambridge, MA), muscle specific actin (clone HHF35; Ventana; Phoenix, AZ); calponin (clone CALP; Dako, Carpinteria, CA); S100 (clone 4C4.9; Ventana); c-kit (clone YR145; Cell Marque); and AE1/AE3 (clone PCK26; Ventana). For a minority of cases, immunohistochemistry had been done at an outside institution and the reported results were recorded. As a surrogate marker for the presence of HPV, p16 immunostaining was regarded as positive only if staining was both nuclear and cytoplasmic, and present in ≥70% of the tumor cells.