Systemic mastocytosis and Sjögren's syndrome.

are more likely to have either contralateral or bilateral bony metastases, which is supported by the recent report' and our case. Fixation, possibly with radiotherapy and cryotherapy, is recommended for a lytic lesion in a weightbearing bone if the life expectancy is greater than three or four months.2 Metastases to periarticular foci are not uncommon, especially in the hip, shoulder, and knee, and the synovial reaction is either non-neoplastic or due to extension through the subchondral bone plate to affect the synovial membrane secondarily.4 There is nothing to suggest in the cases presented that there was primary involvement of the synovium, and we would thus suggest that what has been described is not rare but certainly might have been underreported recently. A H ISDALE School of Medicine Rheumatology and Rehabilitation Research Departmnent University of Leeds 36 Clarendon Road Leeds LS2 9NZ United Kingdom