The authors present a case of angioleiomyoma situated in the posterior knee. A 47-year-old Caucasian woman presented in 2011 with recurrent stabbing pain on the lateral aspect of her right knee. She reported having pain for the last 6years. She had no history of trauma. In 2008 she was treated with a diagnostic arthroscopy and transposition of the tibial tuberosity, with no benefit to her symptoms. Electromyography of the lower limbs showed asymmetry of the amplitude of sensitive action potential of the superficial fibular nerve. Based on the clinical suspicion of entrapment of the common fibular nerve at its bifurcation, a surgical exploration was performed, but pain persisted. In 2014, ultrasonography localized at the trigger point showed a solid ovular formation of 1cm in diameter situated on the posterior aspect of the external femoral condyle in proximity to the joint capsule, which was confirmed by magnetic resonance imaging (MRI). Surgical excision of the 1-cm diameter tumor mass relieved the symptoms immediately and permanently. Histology evidenced the presence of a solid-type angioleiomyoma. The presence of an angioleiomyoma at the knee joint is very rare and few cases are reported in the literature. To the authors' knowledge this is the first time an angioleiomyoma in the posterior knee has been described. In case of unexplained and persistent pain in and around the knee, clinicians should be aware of the atypical locations of this tumor, considering that its surgical excision alone may relieve symptoms permanently.
Keywords: Angioleiomyoma; Knee; Magnetic resonance.
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