ICC and WHO 2022 classification for the diagnosis of mastocytosis
| . | WHO . | ICC . |
|---|---|---|
| CM Urticaria pigmentosa/maculopapular cutaneous mastocytosis • Monomorphic variant • Polymorphic variant Diffuse cutaneous mastocytosis Cutaneous mastocytoma • Isolated mastocytoma • Multilocalized mastocytoma | CM Urticaria pigmentosa/maculopapular cutaneous mastocytosis Diffuse cutaneous mastocytosis Mastocytoma of skin | |
| SM BMM* ISM SSM ASM SM-AHN MCL MC sarcoma | SM ISM (includes BMM) SSM ASM SM-AMN MCL MC sarcoma | |
| B-findings | >30% BM cellularity by MCs in histology and serum tryptase >200 ng/ml and/or KIT D816V VAF >10% in BM or PB leukocytes | >30% of BM cellularity by MC aggregates (assessed on BM biopsy) and serum tryptase >200 ng/mL |
| Hypercellular BM with loss of fat cells and prominent myelopoiesis ± left shift and eosinophilia ± leukocytosis and eosinophilia and/or discrete signs of myelodysplasia (<10% neutrophils, erythrocytes, and megakaryocytes) | Cytopenia (not meeting criteria for C-findings) or cytosis. Reactive causes are excluded, and criteria for other myeloid neoplasms are not met. | |
| Palpable hepatomegaly without ascites or other signs of organ damage and/or palpable splenomegaly without hypersplenism and without weight loss and/or lymphadenopathy (>2 cm) | Hepatomegaly without impairment of liver function and/or splenomegaly without features of hypersplenism including thrombocytopenia and/or lymphadenopathy (>1 cm size) on palpation or imaging | |
| BMM: no B-findings, absence of skin lesionsa basal serum tryptase <125 mg ISM <2 B-findings SSM ≥2 B-findings | ISM <2 B-findings SSM ≥2 B-findings | |
| C-findings | Cytopenias: ANC <1 × 109/L and/or Hb <100 g/L and/or platelets <100 × 109/L | |
| Hepatopathy: ascites and elevated liver enzymes ± hepatomegaly or cirrhotic liver ± portal hypertension | ||
| Spleen: palpable splenomegaly with hypersplenism ± weight loss ± hypoalbuminemia | ||
| GI tract: malabsorption with hypoalbuminemia ± weight loss | ||
| Bone: large-sized osteolysis (≥2 cm) with pathologic fracture bone pain ASM 1 or more C-findings/SM-AHM/AMN and MCL may not have C-findings | ||
| . | WHO . | ICC . |
|---|---|---|
| CM Urticaria pigmentosa/maculopapular cutaneous mastocytosis • Monomorphic variant • Polymorphic variant Diffuse cutaneous mastocytosis Cutaneous mastocytoma • Isolated mastocytoma • Multilocalized mastocytoma | CM Urticaria pigmentosa/maculopapular cutaneous mastocytosis Diffuse cutaneous mastocytosis Mastocytoma of skin | |
| SM BMM* ISM SSM ASM SM-AHN MCL MC sarcoma | SM ISM (includes BMM) SSM ASM SM-AMN MCL MC sarcoma | |
| B-findings | >30% BM cellularity by MCs in histology and serum tryptase >200 ng/ml and/or KIT D816V VAF >10% in BM or PB leukocytes | >30% of BM cellularity by MC aggregates (assessed on BM biopsy) and serum tryptase >200 ng/mL |
| Hypercellular BM with loss of fat cells and prominent myelopoiesis ± left shift and eosinophilia ± leukocytosis and eosinophilia and/or discrete signs of myelodysplasia (<10% neutrophils, erythrocytes, and megakaryocytes) | Cytopenia (not meeting criteria for C-findings) or cytosis. Reactive causes are excluded, and criteria for other myeloid neoplasms are not met. | |
| Palpable hepatomegaly without ascites or other signs of organ damage and/or palpable splenomegaly without hypersplenism and without weight loss and/or lymphadenopathy (>2 cm) | Hepatomegaly without impairment of liver function and/or splenomegaly without features of hypersplenism including thrombocytopenia and/or lymphadenopathy (>1 cm size) on palpation or imaging | |
| BMM: no B-findings, absence of skin lesionsa basal serum tryptase <125 mg ISM <2 B-findings SSM ≥2 B-findings | ISM <2 B-findings SSM ≥2 B-findings | |
| C-findings | Cytopenias: ANC <1 × 109/L and/or Hb <100 g/L and/or platelets <100 × 109/L | |
| Hepatopathy: ascites and elevated liver enzymes ± hepatomegaly or cirrhotic liver ± portal hypertension | ||
| Spleen: palpable splenomegaly with hypersplenism ± weight loss ± hypoalbuminemia | ||
| GI tract: malabsorption with hypoalbuminemia ± weight loss | ||
| Bone: large-sized osteolysis (≥2 cm) with pathologic fracture bone pain ASM 1 or more C-findings/SM-AHM/AMN and MCL may not have C-findings | ||
BM, bone marrow; PB, peripheral blood.