(P 463) EXTRANODAL FOLLICULAR DENDRITIC CELL SARCOMAS AND THEIR OLIGORECURRENCES: TRIUMPHS, TRIALS AND LESSONS LEARNT AT A SINGLE TERTIARY CANCER REFERRAL CENTRE, INDIA.

Objective: Follicular Dendritic Cell Sarcoma (FDCS) is a rare and an aggressive malignant neoplasm, predominantly involving lymph nodes in the head and neck region. These tumors also occur at extra-nodal sites and designated as extranodal (ENFDCSs). Given their rarity, standardized treatment protocols remain elusive, making comprehensive research essential for a better understanding and management of patients harbouring these tumors.

Methods: Patients diagnosed with ENFDCs, who presented to the gastrointestinal oncology unit of a tertiary cancer center were included. Diagnostic confirmation involved positive immunostaining for antibody markers, namely CD21, CD23, and CD35. The treatment details and outcomes were analysed.

Results: Fourteen patients with ENFDCS, (9 males and 4 females), with a median age of 41 years, were included. The sites included the colon (n=6), retroperitoneum (n=3), rectum (n=2) and one tumor each, in the mesentery, liver and pelvis, respectively. Four (30.7%) tumors were initially misdiagnosed. The treatments offered included surgical resection and various chemotherapy regimens as neoadjuvant, adjuvant or for salvage. Among 13 patients, 7 developed recurrences (liver, rectovesical pouch, omentum, peritoneum), while 5 were free of disease.. At a median follow-up of 26 months (range, 7 to 153 months), 2 patients succumbed to the disease and 2 were lost to follow-up. Among 9 alive patients, 5 were disease-free, 4 were on systemic therapy with partial response, and one patient did not show improvement with alternative treatment options and was offered best supportive care. The median overall survival of the cohort was 26 months and the median disease-free survival was 10.5 months.

Conclusion: ENFDCS is an uncommon neoplasm that can be misdiagnosed. Surgery with chemotherapy appears to have a pivotal role, with a role of multimodality treatment in recurrences. .