SUMMARY

• Popliteal Cysts are common soft tissue masses in children that unlike the adult population, are most often not associated with meniscal tears. 

• Diagnosis is suspected clinically with a palpable mass in the popliteal fossa that transilluminates. MRI can confirm the diagnosis of a cystic lesion. 

• Treatment is observation as the majority of lesions spontaneously resolve. 

ETIOLOGY

• Pathoanatomy

  • popliteal cysts usually are located

    • between muscles of

      • semimembranosus

      • medial head of gastrocnemius

    • from herniated posterior knee joint capsule synovium

• • ANATOMY

    • Muscles posterior to medial knee capsule

      • semimembranosus 

      • medial head of gastrocnemius 

PRESENTATION

• Symptoms

  • usually asymptomatic

• Physical exam

  • located in popliteal fossa

    • usually located medially and distal to knee crease

      • most pronounced with knee extended

  • mass will transilluminate

IMAGING

• Radiographs

  • are normal

• Ultrasound

  • consistent with cystic lesion

• MRI

  • show fluid filled cyst

TREATMENT

• Nonoperative

  • observation

    • indications

      • mainstay of treatment

        • with majority of cases resolving spontaneously 

           

• Operative

  • excision

    • indications

      • only if cyst causes significant discomfort

      • failure of spontaneous resolution