We would like to report a probable side effect of highdose methotrexate (MTX) in a patient during treatment of acute childhood lymphoblastic leukaemia (ALL).
The patient, a 14-year-old girl, was diagnosed with ALL (hyperdiploid precursor B-cells, low leucocyte type) in July 1998 and treated as an intermediate-risk case according to NOPHO ALL protocol [1]. The treatment in question consists of two induction phases'' (weeks 1ยฑ 12 and 24ยฑ30). In between, a consolidation phase'' of high-dose MTX (5 g/m 2 ) is given as 24-hr infusions followed by folinic acid rescue in weeks 16, 18, 20 and 22. In addition, oral mercaptopurine (6-MP) (25 mg/m 2 ) is given daily during the whole consolidation period. After the second induction phase, the ``maintenance phase'' or continuing treatment consists of oral 6-MP (75mg/m 2 ) daily and MTX (20 mg/m 2 ) weekly for a total treatment time of 2 years. During the ยฎrst part of the continuing treatment monthly reinductions are given, consisting of ยฎve infusions of high-dose MTX (5 g/m 2 ) alternating with intravenously administered vincristine (2 mg/m 2 , maximal dose 2 mg) and oral prednisolone (60 mg/m 2 ) daily for 7 days.
The patient presented with a swollen and tender Achilles tendon on the right after the second MTX infusion in the consolidation phase (week 19), and a few days later on the left side too. After rest and local treatment with ice packs both heels recovered after about a week. Right-sided Achilles tendinitis recurred four months later, after the second induction phase, 18 days after the ยฎrst of the ยฎve MTX infusions. Treatment with a single dose of ibuprophene (600 mg) did not prevent tendinitis from developing on the left three days later. Both heels recovered after about 10 days. Exactly the same clinical picture occurred after the last MTX infusion, about 6 months later. The right heel was affected on the 19th day and the other side 3 days later. After the same dose of ibuprophene and 10 days of rest and use of crutches, both heels had recovered.
To summarize, three similar episodes of bilateral Achilles tendinitis occurred at about the same time after a high-dose infusion of MTX. No other tendons were affected, either during these episodes or during the whole treatment period. The ALL as such showed a good early response to the treatment and no other unexpected side effects were seen.
The development of tendinitis could hardly be explained by any physical activity. The patient stayed in bed