A child was born with features consistent with Down syndrome. Karyotype results were 46,XY,der(21;21)(q10;q10),+21, supporting the clinical diagnosis. Parental chromosomal analysis was completed as a follow-up. The mother’s karyotype was normal, and the father’s karyotype is shown in the image.

	Nicole Boczek, Ph.D. Fellow, Cytogenetics Mayo Clinic
	Nicole Hoppman, Ph.D. Consultant, Laboratory Genetics Mayo Clinic Assistant Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine

A 13-month-old female infant was referred for delayed milestones, atrial septal defect, low-set ears, mild hypertelorism, and iridal coloboma. Chromosome analysis was performed, which showed a 47,XX,+mar karyotype (Figure 1A), with a small bisatellited supernumerary marker chromosome. Slides were stained with DAPI, and the marker was DAPI negative (Figure 1B). A chromosomal microarray was performed, which revealed four copies of proximal 22q.

	Patrick Blackburn, Ph.D. Fellow, Laboratory Genetics and Genomics Mayo Clinic
	Hutton Kearney, Ph.D. Consultant, Laboratory Genetics/Genomics Mayo Clinic Assistant Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine

A 59-year-old man with a history of HIV presented with a 6 cm mass involving the left palatine tonsil. Biopsy of the mass showed the histologic findings seen below. Initial immunohistochemical stains including pankeratin, p63, and S100 were negative.

Additional immunohistochemical stains revealed the following immunophenotype:

	Rosalind Sharain, M.D. Fellow, Cytopathology Mayo Clinic
	Linda Dao, M.D. Consultant, Anatomic Pathology Mayo Clinic Assistant Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine

The patient is a 59-year-old man with a 12-month history of progressive erythematous and non-pruritic skin rashes (Figure 1) associated with arthralgias, neuropathy, nasal congestion, and loss of eyebrow hair. On physical exam, the patient had demonstrable paresthesias in the distribution of the rash. The patient was born in the United States but had an extensive international travel history, including trips to western Mexico within the past 10 to 15 years. The histopathologic findings are shown in Figure 2 (H&E) and Figure 3 (Fite stain).

	Elise Venable, M.B.B.S. Resident, Anatomic and Clinical Pathology Mayo Clinic
	Bobbi Pritt, M.D. Consultant, Clinical Microbiology Mayo Clinic Professor of Laboratory Medicine and Pathology Mayo Clinic College of Medicine