Introduction: Nodular fasciitis is a rare, benign soft tissue lesion that can prove to be difficult to diagnose, especially when intra-articular.
Case presentation: A 17-year-old female softball player presents with several year history of right knee pain and swelling initially attributed to patellar maltracking refractory to non-operative and operative management.
Management and outcomes: Initial pathology suggested tenosynovial giant cell tumor; however, further tissue diagnosis revealed nodular fasciitis, which was eventually resected.
Conclusion: Intra-articular nodular fasciitis of the knee is rare and may easily be misdiagnosed due to its nonspecific clinical presentation. Careful histological examination can aid in diagnosis. Nodular fasciitis should be considered in the differential diagnoses for intra-articular lesions of the knee joint.
Keywords: Nodular fasciitis; intra-articular nodular fasciitis; knee.