Fluctuant Subcutaneous Nodule in the Axilla of an Adolescent Female

A 15-year-old adolescent female with an unremarkable medical history presented to the dermatology clinic with a mass in the left axilla of 2 years' duration.The patient reported that there was no drainage of the lesion nor did she have any other similar lesions.She reported tenderness of the lesion during menstruation that resolved after this phase ended.Dermatologic examination revealed a solitary 4.4-cm, flesh-colored, poorly defined, boggy, fluctuant subcutaneous nodule with no central punctum or surface changes.Ultrasonography of the axilla showed a 6.4-cm hypoechoic heterogenous mass.A biopsy of the lesion was performed. WHAT'S YOUR DIAGNOSIS?a. accessory breast b. epidermoid inclusion cyst c.