Instructions: Read the following cases and answer the questions accordingly. Type your answer after each question.
Case 1
The mother of a 3-year-old girl brings the child in for the evaluation of a “wart” on her thumb. It has been present for 3 or 4 days and seems to cause some pain. The week prior, the child had a “head cold” and “cold sores “around her mouth, all of which have resolved. She has never had warts, and the mother says that the child is otherwise healthy. On examination, you see a well appearing child who is sitting in her mother’s lap and sucking her thumb. Her head and neck exam is normal. On her left thumb, just proximal to the base of the thumbnail, is the lesion about which the mother is concerned. It is a cluster of small vesicles with a faint area of surrounding erythema. The remainder of the child’s examination is normal.
1. What virus is the most likely cause of this skin lesion?
2. How was it transmitted to this patient’s thumb?
Case 2
A 28-year-old man presents to the physician’s office for evaluation of a rash on his chest. He started with one oval-shaped purplish area that he thought was a bruise but has subsequently developed multiple new lesions. The growths don’t hurt, itch, or bleed, but he continues to get new ones, and the existing ones are getting larger. He has never had anything like this before, has no history of allergies and denies exposure to any new medications, foods, lotions, or soaps. His past medical and family histories are unremarkable. His review of systems is significant for a 15-lb weight loss in the past 2 months, approximately 6 weeks of diarrhea, and a 3-week history of a sore throat. On examination, he is a thin but generally well appearing male. His vital signs are normal. Examination of his pharynx shows thick white plaques on the posterior pharynx and soft palate. On the skin of his chest are multiple oval-shaped purple or brown macules. They are firm on palpation and vary in size from 0.5 to 4 cm in length. Several of them appear to be growing together into larger, confluent plaques. You perform a punch biopsy of one of the lesions. In 5 days you get the pathology report with the diagnosis of Kaposi sarcoma.
1. With what virus is this patient likely infected?
2. What specific cell types are most commonly infected with this virus? What cell surface receptor is the binding site of this virus?
3. What serologic testing is most frequently performed to make this diagnosis?