Comparison of demographic, clinical, and laboratory characteristics between ISM subgroups
| Characteristic . | No. (%) of patients . | Median (range) . | ISM-other, no. (%) . | BMM, no. (%) . | SSM, no. (%) . | P . |
|---|---|---|---|---|---|---|
| Total no. of ISM | 159 | — | 101 (63) | 36 (23) | 22 (14) | |
| Demographic characteristics | ||||||
| Male | 69 (43) | — | 39 (39) | 21 (58) | 9 (69) | NS |
| Age, y | — | 49 (19-84) | 48 (21-84) | 45 (19-77) | 64 (38-78) | < .001 |
| Time from symptoms to SM diagnosis, mo | 72 (0-516) | 72 (0-516) | 48 (0-204) | 114 (1-372) | .005 | |
| Clinical characteristics | ||||||
| Urticaria pigmentosa | 100 (63) | — | 86 (85) | n/a | 14 (64) | n/a |
| Cutaneous symptoms* | 119 (75) | — | 79 (78) | 26 (72) | 14 (64) | NS |
| Constitutional symptoms* | 30 (19) | — | 15 (15) | 5 (14) | 10 (45) | .003 |
| Mediator-related symptoms* | 110 (69) | — | 68 (67) | 31 (86) | 11 (50) | .01 |
| Idiopathic and/or recurrent anaphylactoid reaction* | 53 (33) | — | 21 (21) | 28 (78) | 4 (18) | < .001 |
| Musculoskeletal symptoms* | 48 (30) | — | 36 (36) | 7 (19) | 5 (23) | NS |
| Gastrointestinal symptoms* | 113 (71) | — | 70 (69) | 26 (72) | 17 (77) | NS |
| Hepatomegaly | 22 (14) | — | 10 (10) | 0 (0) | 12 (55) | n/a |
| Splenomegaly (n = 157) | 26 (17) | — | 11 (11) | 0 (0) | 15 (68) | n/a |
| Lymphadenopathy† | 22 (14) | — | 13 (13) | 0 (0) | 9 (41) | n/a |
| B-findings | ||||||
| BM MC > 30% or serum tryptase > 200 ng/mL | 23 (14) | — | 8 (8) | 0 (0) | 15 (68) | n/a |
| Hypercellular BM or dysmyelopoiesis, without cytopenias | 13 (8) | — | 2 (2) | 0 (0) | 11 (50) | n/a |
| Hepatosplenomegaly and/or LNP without functional impairment | 41 (26) | — | 21 (21) | 0 (0) | 20 (91) | n/a |
| Laboratory characteristics | ||||||
| Hemoglobin, g/dL | 158 (99) | 13.9 (8.1-16.7) | 13.9 (10.6-16.7) | 14.4 (8.6-16.3) | 12.4 (8.1-15.2) | < .001 |
| White blood cell count, ×109/L | 157 (99) | 6.6 (1.6-19.3) | 6.8 (1.6-15.2) | 6.3 (2.8-9.9) | 6.7 (2.9-19.3) | NS |
| Platelet count, ×109/L | 152 (96) | 260 (39-570) | 270 (39-563) | 273 (160-500) | 218 (73-570) | NS |
| Serum tryptase, ng/mL | ||||||
| < 11.5 | 90 (57) | 54 (11.4-1410) | 66.3 (13.1-440) | 25.9 (11.4-60.5) | 212.5 (106-1410) | < .001 |
| ≥ 11.5 | 89 (99) | — | 54 (100) | 23 (96) | 12 (100) | NS |
| ≥ 200 | 11 (12) | — | 3 (6) | 0 (0) | 8 (67) | < .001 |
| Urine histamine, μg/g Cr/24 h | ||||||
| < 35 | 34 (21) | 49 (17-986) | 61 (17-581) | 30 (18-82) | 208 (198-986) | .002 |
| ≥ 35 | 21 (62) | — | 16 (76) | 2 (20) | 3 (100) | .004 |
| Urine N-methylhistamine | ||||||
| 30-200 μg/g Cr | 51 (32) | 335 (33-4156) | 502 (52-2376) | 208 (33-515) | 2208 (141-4156) | < .001 |
| > UNL | 41 (80) | — | 28 (90) | 8 (53) | 5 (100) | .006 |
| Urine beta PG-F2α | ||||||
| ≤ 1000 ng/24 h | 72 (45) | 1880 (119-13 100) | 2409 (119-13 100) | 1132 (159-7477) | 8838 (465-12 633) | .007 |
| > UNL | 50 (69) | — | 31 (78) | 13 (52) | 6 (86) | NS |
| BM % MC | 141 (89) | 10 (1-90) | 10 (1-60) | 5 (5-20) | 40 (8-90) | < .001 |
| Characteristic . | No. (%) of patients . | Median (range) . | ISM-other, no. (%) . | BMM, no. (%) . | SSM, no. (%) . | P . |
|---|---|---|---|---|---|---|
| Total no. of ISM | 159 | — | 101 (63) | 36 (23) | 22 (14) | |
| Demographic characteristics | ||||||
| Male | 69 (43) | — | 39 (39) | 21 (58) | 9 (69) | NS |
| Age, y | — | 49 (19-84) | 48 (21-84) | 45 (19-77) | 64 (38-78) | < .001 |
| Time from symptoms to SM diagnosis, mo | 72 (0-516) | 72 (0-516) | 48 (0-204) | 114 (1-372) | .005 | |
| Clinical characteristics | ||||||
| Urticaria pigmentosa | 100 (63) | — | 86 (85) | n/a | 14 (64) | n/a |
| Cutaneous symptoms* | 119 (75) | — | 79 (78) | 26 (72) | 14 (64) | NS |
| Constitutional symptoms* | 30 (19) | — | 15 (15) | 5 (14) | 10 (45) | .003 |
| Mediator-related symptoms* | 110 (69) | — | 68 (67) | 31 (86) | 11 (50) | .01 |
| Idiopathic and/or recurrent anaphylactoid reaction* | 53 (33) | — | 21 (21) | 28 (78) | 4 (18) | < .001 |
| Musculoskeletal symptoms* | 48 (30) | — | 36 (36) | 7 (19) | 5 (23) | NS |
| Gastrointestinal symptoms* | 113 (71) | — | 70 (69) | 26 (72) | 17 (77) | NS |
| Hepatomegaly | 22 (14) | — | 10 (10) | 0 (0) | 12 (55) | n/a |
| Splenomegaly (n = 157) | 26 (17) | — | 11 (11) | 0 (0) | 15 (68) | n/a |
| Lymphadenopathy† | 22 (14) | — | 13 (13) | 0 (0) | 9 (41) | n/a |
| B-findings | ||||||
| BM MC > 30% or serum tryptase > 200 ng/mL | 23 (14) | — | 8 (8) | 0 (0) | 15 (68) | n/a |
| Hypercellular BM or dysmyelopoiesis, without cytopenias | 13 (8) | — | 2 (2) | 0 (0) | 11 (50) | n/a |
| Hepatosplenomegaly and/or LNP without functional impairment | 41 (26) | — | 21 (21) | 0 (0) | 20 (91) | n/a |
| Laboratory characteristics | ||||||
| Hemoglobin, g/dL | 158 (99) | 13.9 (8.1-16.7) | 13.9 (10.6-16.7) | 14.4 (8.6-16.3) | 12.4 (8.1-15.2) | < .001 |
| White blood cell count, ×109/L | 157 (99) | 6.6 (1.6-19.3) | 6.8 (1.6-15.2) | 6.3 (2.8-9.9) | 6.7 (2.9-19.3) | NS |
| Platelet count, ×109/L | 152 (96) | 260 (39-570) | 270 (39-563) | 273 (160-500) | 218 (73-570) | NS |
| Serum tryptase, ng/mL | ||||||
| < 11.5 | 90 (57) | 54 (11.4-1410) | 66.3 (13.1-440) | 25.9 (11.4-60.5) | 212.5 (106-1410) | < .001 |
| ≥ 11.5 | 89 (99) | — | 54 (100) | 23 (96) | 12 (100) | NS |
| ≥ 200 | 11 (12) | — | 3 (6) | 0 (0) | 8 (67) | < .001 |
| Urine histamine, μg/g Cr/24 h | ||||||
| < 35 | 34 (21) | 49 (17-986) | 61 (17-581) | 30 (18-82) | 208 (198-986) | .002 |
| ≥ 35 | 21 (62) | — | 16 (76) | 2 (20) | 3 (100) | .004 |
| Urine N-methylhistamine | ||||||
| 30-200 μg/g Cr | 51 (32) | 335 (33-4156) | 502 (52-2376) | 208 (33-515) | 2208 (141-4156) | < .001 |
| > UNL | 41 (80) | — | 28 (90) | 8 (53) | 5 (100) | .006 |
| Urine beta PG-F2α | ||||||
| ≤ 1000 ng/24 h | 72 (45) | 1880 (119-13 100) | 2409 (119-13 100) | 1132 (159-7477) | 8838 (465-12 633) | .007 |
| > UNL | 50 (69) | — | 31 (78) | 13 (52) | 6 (86) | NS |
| BM % MC | 141 (89) | 10 (1-90) | 10 (1-60) | 5 (5-20) | 40 (8-90) | < .001 |
ISM indicates indolent systemic mastocytosis (SM); SSM, smoldering SM; BMM, isolated bone marrow mastocytosis; BM, bone marrow; MC, mast cell; LNP, lymphadenopathy; PG, prostaglandin; UNL, upper normal limit; Cr, creatinine; NS, not significant; n/a, not applicable; and —, unknown or not done. SSM is defined by the presence of 2 or more “B-findings” (ie, BM MC > 30% or serum tryptase > 200 ng/mL, BM hypercellularity or dysmyelopoiesis without cytopenias, and organomegaly and/or lymphadenopathy without functional impairment). Causes of death were available for 14 of the 26 deaths: disease transformation (n = 4; all SSM), cardiovascular (n = 3; all ISMo), solid tumor (n = 4; 3 ISMo and 1 BMM), complications of MC mediator release (n = 2; 1 each SSM and ISMo), and infection (n = 1; SSM).
As defined in Lim et al.2
Either palpable or detected by imaging studies.