The negative prognostic consequences of extramedullary plasmacytomas in the context of symptomatic MM is well known. On the contrary, the clinical impact of bone plasmacytomas (BP) has not been extensively studied, although their presence is one of Duries’ major MM diagnostic criteria.

The aim of the present study was to study eventual differences between MM patients presenting at diagnosis with or without BP.

Patients and Methods

Two hundred and twelve symptomatic MM patients were studied from diagnosis to last follow-up. Their median age was 66 years and 60% were men. Twenty-three percent, 27% and 50% of patients were in ISS stage 1, 2 and 3 respectively; MM type was IgG in 59% , IgA in 26%, light chain only in 12%, IgD in 1,5% and non- or oligo-secretory in 1,5%. All patients required treatment and BP ones were additionally given radiotherapy. The median follow-up time of the whole cohort was 46,4 months.

Results

Forty patients (19%) had a BP at the time of their diagnosis. BP was located in the spine (BP-S) in 19 out of 40 and in other sites (BP-O: skull, pelvis, long bones, and ribs) in 21 patients. BP patients had equivalent demographics, stage and MM type as the others. Non-BP patients tended to have a better survival than BP ones but the difference was not statistically significant (p=0.1). However, BP-S patients had a significantly worse outcome than BP-O patients (24±6 versus 48±11 months, p<0.00001), and indeed worse than non-BP patients. It is worthwhile to outline that 17 out of 19 BP-S patients had received new drugs (thalidomide, lenalidomide, Bortezomib) during their course while 8 of them underwent high dose treatment with autologous stem-cell transplantation. In addition, the ISS staging has absolutely no prognostic impact in these patients (p=0.5), on the contrary to the whole cohort (p=0.03).

In conclusion, MM patients presenting spine plasmacytoma at diagnosis constitute a distinct subgroup with adverse outcome that is difficultly predictable, given that the current staging system does not separate them. Further confirmation of this finding in larger cohorts is needed, as well as exploration of the biologic background.

Disclosures:

No relevant conflicts of interest to declare.

Author notes

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Asterisk with author names denotes non-ASH members.

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