Isolated CNS Relapse in Acute Lymphoblastic Leukemia (ALL): An Experience from a Tertiary Care Center.

In this study the various parameters of acute lymphoblastic leukemia (ALL), including the clinical features, peripheral blood and bone marrow (BM) findings, immunophenotypic and cytogenetic details in ALL cases who had isolated relapse involving the central nervous system (CNS), were studied.  Duration of the study is from 2015 to 2019 in which 5 ALL cases were presented to this tertiary care center. The presenting symptoms varied from headache, fever, and distension of abdomen. These cases were either on therapy or post completion of chemotherapy. The diagnosis of CNS relapse followed after the examination of cerebrospinal fluid (CSF). Patients also underwent BM examination to rule out systemic relapse.  Age of patients ranged from 7 months to 42 years. There were three female patients. Two patients had isolated CNS relapse 3.5 years after completing therapy and succumbed to their illness. Two patients had t(9;22) while one patient had t(1;14) cytogenetic abnormality at diagnosis. One patient was diagnosed as T-ALL. Treatment offered was German Multicentre ALL protocol for induction along with 10 cycles of maintenance.  The most common hematolymphoid malignancy in children namely ALL accounts for 75% of childhood leukemias. Complete remission rates reach up to 70 to 80%. CNS involvement is known to occur in these cases. CNS relapse may occur alone or with systemic relapse. Advances in therapeutic protocols along with CNS prophylaxis have drastically brought down the rates of CNS relapse. It is essential to maintain a high degree of suspicion so that these cases of isolated CNS relapse can be identified at the earliest and definitive therapy can be offered.