A 65-year-old man with history of treated anal intraepithelial neoplasia presents with new-onset diarrhea. A Papanicolaou-stained anal smear was performed for follow-up cancer screening.

	Nicholas Boire, M.D., M.S. Resident, Anatomic and Clinical Pathology Mayo Clinic @DrBoire
	Bobbi Pritt, M.D. Consultant, Clinical Microbiology Mayo Clinic Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine and Science @ParasiteGal
	Charles Sturgis, M.D. Senior Associate Consultant, Anatomic Pathology Mayo Clinic

78 year old man with new onset bilateral shoulder/neck pain and weakness, jaw pain exacerbated by chewing, and odynophagia with both solids and liquids. A vascular biopsy was performed (see virtual slide).

	Alessia Buglioni, M.D. Resident, Anatomic and Clinical Pathology Mayo Clinic
	John Cheville, M.D. Consultant, Anatomic Pathology Mayo Clinic Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine and Science

A 43-year-old female presents with seizures following weeks of progressive lower extremity numbness. Imaging reveals a contrast-enhancing parasagittal brain mass without other systemic findings. She underwent brain biopsy (see photomicrographs below). Additional immunohistochemical stains for CD30, ALK, and infection (toxoplasma, HSV, CMV, VZV, adenovirus) are negative. EBV in situ hybridization is negative. Clonal T-cell receptor gene rearrangement is detected by molecular analysis.

	Daniel (Dan) P. Larson, M.D. Resident, Hematopathology Mayo Clinic
	William Macon, M.D. Consultant, Hematopathology Mayo Clinic Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine and Science

A 71 yr old female with a history of a central nervous system lymphoma, an allogenic stem cell transplant and graft versus host disease was tested for hereditary hemochromatosis. DNA extracted from whole blood was tested by a multiplex PCR based assay utilizing a Mass Array platform. Molecular testing showed two copies of mutated C282Y allele, two copies of wild type H63H allele and a small fraction of wild type C282C and mutated H63D (mass spectra below). Sanger sequencing confirmed these results.

	Katarzyna Thompson, Ph.D. Fellow, Laboratory Genetics and Genomics Mayo Clinic
	Kandelaria (Ande) Rumilla, M.D. Consultant, Laboratory Genetics and Genomics Mayo Clinic Assistant Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine and Science