1. Presented by Katie Fomchenko, M.D. and reviewed by Sean Zhang, M.D., Ph.D.

An adult presented with multiple painful skin lesions. The lesions started as small bumps that the patient assumed were bug bites, but have progressed to larger well circumscribed ulcerated lesions, one of which has become inflamed, warm, and has purulent discharge, over 2-4 weeks. They  report being intermittently febrile, with recent travel to a tropical country, where they enjoyed hiking, swimming, and exploring caves. They did not take any prophylactic medications or receive any vaccinations before traveling. Aside from the ulcers, his physical exam is normal.

The physician orders a CBC and performs a biopsy of the ulcerated lesions. The results are as follows:

Test	Reference Range	Patient Value
WBC	4.5-11 K/cu mm	12.5 (H)
RBC	4.5-5.9 M/cu mm	3.58
Hemoglobin	13.9-16.3 g/dL	12.3
Hematocrit	41-53%	37.5
Platelets	150-350 K/cu mm	257

The skin biopsy reveals reactive squamous mucosa, granulation tissue, and the following is seen:

What is the most likely diagnosis?