Monthly swelling of the knee - Case report and review of the literature

Introduction: We report a 17-year old with monthly swelling of her knee. The complaints are associated with the menstrual cycle. After physical examination, radiographs, MRI and an arthroscopy with biopsies, a diagnosis of intra-articular endometriosis and menstrual arthritis was made.

Discussion: Both an intra-articular manifestation of endometriosis and menstrual arthritis are very rare diagnoses. Extraperitoneal lesions of endometriosis are rare and the mechanism for spreading outside the retroperitoneal space is unknown. A similar situation exists for menstrual arthritis, it is thought that cytokines, which are produced as a reaction to retrograde menstruation, are the trigger for menstrual arthritis. A review of literature is given.

Conclusion: A monthly recurrent, painful swelling of a joint, can and should give rise to thorough investigation. Differential diagnostic one should think of intra-articular manifestation of endometriosis and menstrual arthritis. We give a proposal for treatment.