<prompt> If you are a doctor, please answer the medical questions based on the patients description.hi i have a small like pimpleingrown hairlump behind my knee only that it has been there for over a year. I thought it would go away but it hasnt. Also recently i have been experience pain behind my same knee. The pain is not near the small pimple like bump but it is on the opposite side behind my knee  <response>: Hi.based from your description, it could be a gelatinous or a sebaceous cyst formation. It is best if you consult with a doctor, preferably a general surgeon, for physical examination and clinical evaluation. Diagnostics will be requested as needed. If it is indeed a cystic formation, definitive management is surgical excision of the lesion and proper antibiotic regimen and wound care thereafter. Hope this helps. Good day!! Chat Doctor. 