Young man with a rash on shoulder

A young man in his 30’s, with no significant PMH, comes to the office after noticing a pruritic rash on the Lt shoulder and pain in the Lt axilla that started after working in his father’s basement yesterday. The symptoms started late in the evening and worsened over the past 12- 24 hrs. He denies fever, chills, nausea or vomiting. He thinks that he might have been bitten by an insect, but cannot say for sure. He also spent some time working in the back yard, a day earlier. He is not sure if he came in contact with chemicals while working in the basement. On exam, his vital signs are stable. He has a 5- 6 cm well demarcated, erythematous macular rash on the Lt shoulder with a linear extension to the Lt axilla. A solitary, tender, mobile lymph node is appreciated on the anterior axillary fold. What is the most likely diagnosis?

1. Ringworm infection
2. Cellulitis and secondary lymphangitis from an insect bite- ANSWER.
3. Contact dermatitis
4. Folliculitis
5. Erythema migrans