Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. T-cell ALL accounts for 10% to 15% of cases. Acute lymphoblastic leukemia can rarely relapse in unusual extra medullary sites like bone. Hereby, we report a case of 7-years old male child presented with left arm swelling, initially confused with bone tumor but later found to be infiltration by leukemic blasts. We reviewed all previous cases and suggest that in a patient of ALL presenting with a bone swelling during or after completion of therapy, one should suspect of bone relapse.