The concomitant presence of lupus anticoagulant, anticardiolipin and anti‐β2‐glycoprotein i antibodies could be associated with acquired activated protein c resistance in non‐systemic lupus erythematosus patients

We read with interest the multicentre study on the use of alpha-interferon (IFN-a) in systemic mastocytosis (SM) (Casassus et al, 2002). We would like to make several comments. Although there was a good response to some symptoms in the group, this was at the expense of significant sideeffects. Bone pain appeared to be the most frequent symptom and showed improvement. However, we have found very good symptomatic relief of bone pain with bisphosphonate treatment in three patients with SM. One patient, a 42-year-old man, presented with long-standing and severe, refractory bone pain. Magnetic resonance imaging (MRI) demonstrated highly atypical multifocal marrow abnormalities that were suggestive of widespread metastatic disease. The diagnosis of SM was made after extensive malignancy screening, a repeat MRI and a bone marrow trephine, which was grossly fibrotic with mild myelodysplasia and abnormal mast cells. Monthly pamidronate infusions not only produced significant pain relief, but a repeat MRI after 19 months of treatment also demonstrated the improvement of bone marrow appearance. This was suggestive of a direct effect on mast cell production by the bisphosphonates, analogous to the effect of nitrogen-containing bisphosphonates in myeloma. The stronger bisphosphonate zoledronic acid may be even better in both respects and we are currently carrying out a trial to compare the two. A second patient with SM, a 48year-old man who presented with pelvic pain, also had widespread MRI abnormalities of both the axial and appendicular skeleton. He has received pamidronate infusions monthly for 4 months, which has led to a good resolution of bone pain. A third patient with bone pain also demonstrated significant pain relief from pamidronate, but unfortunately suffered a delayed allergic reaction (by 12 h), which required admission and steroids to settle. As with all drugs, the possibility of allergic reactions in SM has to be carefully monitored, although the delayed nature of this reaction was unusual. In general, bisphosphonates would appear to be a better option for control of bone pain in SM rather than a-interferon, as the latter has many side-effects that are often similar to the patient’s symptoms.