CLINICOPATHOLOGICAL FEATURES OF RETINOBLASTOMA AFTER PRIMARY CHEMOREDUCTION

Background: Primary chemotherapy is a new treatment approach in retino blastoma, aiming to avoid radiogenic adverse effects, such as second t umor-associated mortality, as observed following external beam irradia tion. Objective: To describe the clinical and histopathologic regressi on pattern after primary chemotherapy in retinoblastoma. Methods: Five patients with sporadic bilateral retinoblastoma underwent planned enu cleation of their functionally blind eye after 2, 3 (in 2 patients), 4 , and 6 courses of primary chemotherapy with carboplatin, etoposide, c yclophosphamide, and vincristine. The eyes were examined histopatholog ically, using light microscopy and immunohistochemical analysis with p roliferation markers. Results: One patient had a type 1 (cottage chees e) regression and 4 patients had either a type 2 (fish flesh) or a typ e 3 (combined) regression pattern. Histopathologic examination reveale d a complete tumor necrosis in 1 patient with type 1 regression after 3 courses of chemotherapy and in 1 patient with type 3 regression afte r 4 courses of chemotherapy. The remaining 3 patients with type 2 or t ype 3 regression had histologically still active proliferative tumor c ells after 2, 3, and 6 courses of chemotherapy. Conclusion: This artic le correlates histopathologically the clinically described efficacy of primary chemotherapy in the treatment of retinoblastoma, underlining, however, the necessity of careful observation and the use of ancillar y treatment whenever there is no complete tumor regression.