Painless swelling in axilla

A 26-year-old woman, librarian, gravida 1, para 1 presented two weeks postpartum comes to the office complaining of painless swelling of her left axilla. Her medical history was notable for sickle cell anemia. Her pregnancy was unremarkable, resulting in the spontaneous vaginal delivery of a healthy infant. Her immediate postpartum course was unremarkable, and she was currently breastfeeding. She denied any fever or signs of systemic infection. Vital signs are within the normal limit. BMI is 28 Kg/m². On physical examination, a mobile 3 × 4 cm non-tender swelling was noted in the left axilla is shown below. There were no signs of local, regional or systemic infection. Based on given the history and the results of the physical examination,