Recurrence of a Benign Tumor: The Challenge of a Knee Intra-articular Schwannoma - A Case Report.

INTRODUCTION: Recurrent intra-articular knee schwannoma is an extremely rare occurrence of an already rare tumor, with no previously documented cases in the literature. CASE REPORT: We present the case of a 42-year-old female from South India who underwent surgical excision for a recurrent Hoffa fat pad (HFP) schwannoma 20 years following the initial excision. Clinical examination revealed a long-standing painless swelling that had gradually increased in size over a decade, with the recent onset of pain. Magnetic resonance imaging demonstrated a multilobulated lesion within the HFP. Histopathological examination and immunohistochemical analysis confirmed the diagnosis of a schwannoma. Complete excision via the medial parapatellar approach resulted in relief of symptoms with no evidence of re-recurrence at 3-year follow-up. CONCLUSION: This case highlights the importance of considering schwannoma as a potential differential diagnosis for HFP tumors and recognizing the possibility of recurrence, thereby facilitating timely diagnosis and effective management.