A 50-year-old man presents to the emergency department with a 3-week history of a cutaneous eruption on the trunk and extremities. He states that the lesions began on his chest and abdomen and continued to progress to his arms and legs. Prior to the onset of the rash, he experienced a febrile illness with pharyngitis that was self-limited and resolved after 7 days. On examination, there are scattered petechiae, purpuric patches and plaques with an erythematous border on the trunks and extremities, some palpable and with central hemorrhagic bullae (20).
i. What is the most likely cause of these lesions and what are the characteristic histological findings?
ii. What are the common causes of this condition?
iii. What laboratory tests should be performed in the initial work-up of this condition?